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CBOR Encoded X.509 Certificates (C509 Certificates)
draft-ietf-cose-cbor-encoded-cert-11

Document Type Active Internet-Draft (cose WG)
Authors John Preuß Mattsson , Göran Selander , Shahid Raza , Joel Höglund , Martin Furuhed
Last updated 2024-07-08
Replaces draft-mattsson-cose-cbor-cert-compress
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draft-ietf-cose-cbor-encoded-cert-11
Network Working Group                                  J. Preuß Mattsson
Internet-Draft                                               G. Selander
Intended status: Standards Track                             Ericsson AB
Expires: 9 January 2025                                          S. Raza
                                                              J. Höglund
                                                                 RISE AB
                                                              M. Furuhed
                                                             Nexus Group
                                                             8 July 2024

          CBOR Encoded X.509 Certificates (C509 Certificates)
                  draft-ietf-cose-cbor-encoded-cert-11

Abstract

   This document specifies a CBOR encoding of X.509 certificates.  The
   resulting certificates are called C509 Certificates.  The CBOR
   encoding supports a large subset of RFC 5280 and all certificates
   compatible with the RFC 7925, IEEE 802.1AR (DevID), CNSA, RPKI, GSMA
   eUICC, and CA/Browser Forum Baseline Requirements profiles.  When
   used to re-encode DER encoded X.509 certificates, the CBOR encoding
   can in many cases reduce the size of RFC 7925 profiled certificates
   with over 50% while also significantly reducing memory and code size
   compared to ASN.1.  The CBOR encoded structure can alternatively be
   signed directly ("natively signed"), which does not require re-
   encoding for the signature to be verified.  The document also
   specifies C509 Certificate Signing Requests, C509 COSE headers, a
   C509 TLS certificate type, and a C509 file format.

About This Document

   This note is to be removed before publishing as an RFC.

   Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-ietf-cose-cbor-encoded-cert/.

   Discussion of this document takes place on the CBOR Object Signing
   and Encryption Working Group mailing list (mailto:cose@ietf.org),
   which is archived at https://mailarchive.ietf.org/arch/browse/cose/.
   Subscribe at https://www.ietf.org/mailman/listinfo/cose/.

   Source for this draft and an issue tracker can be found at
   https://github.com/cose-wg/CBOR-certificates.

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Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 9 January 2025.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   5
   3.  C509 Certificate  . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Message Fields  . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  Encoding of subjectPublicKey and issuerSignatureValue . .   9
     3.3.  Encoding of Extensions  . . . . . . . . . . . . . . . . .  10
     3.4.  COSE Header Parameters  . . . . . . . . . . . . . . . . .  15
     3.5.  Private Key Structures  . . . . . . . . . . . . . . . . .  16
   4.  C509 Certificate Signing Request  . . . . . . . . . . . . . .  17
   5.  C509 Processing and Certificate Issuance  . . . . . . . . . .  19
   6.  Legacy Considerations . . . . . . . . . . . . . . . . . . . .  20
   7.  Expected Certificate Sizes  . . . . . . . . . . . . . . . . .  21
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  22
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  22
     9.1.  C509 Certificate Types Registry . . . . . . . . . . . . .  23

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     9.2.  C509 Certificate Request Types Registry . . . . . . . . .  23
     9.3.  C509 Attributes Registry  . . . . . . . . . . . . . . . .  24
     9.4.  C509 Extensions Registry  . . . . . . . . . . . . . . . .  28
     9.5.  C509 Certificate Policies Registry  . . . . . . . . . . .  33
     9.6.  C509 Policies Qualifiers Registry . . . . . . . . . . . .  35
     9.7.  C509 Information Access Registry  . . . . . . . . . . . .  36
     9.8.  C509 Extended Key Usages Registry . . . . . . . . . . . .  38
     9.9.  C509 General Names Registry . . . . . . . . . . . . . . .  40
     9.10. C509 Signature Algorithms Registry  . . . . . . . . . . .  41
     9.11. C509 Public Key Algorithms Registry . . . . . . . . . . .  46
     9.12. COSE Header Parameters Registry . . . . . . . . . . . . .  49
     9.13. Media Type application/cose-c509-cert . . . . . . . . . .  49
     9.14. Media Type application/cose-c509-pkcs10 . . . . . . . . .  50
     9.15. Media Type application/cose-c509-privkey  . . . . . . . .  51
     9.16. Media Type application/cose-c509-pem  . . . . . . . . . .  52
     9.17. CoAP Content-Formats Registry . . . . . . . . . . . . . .  53
     9.18. TLS Certificate Types Registry  . . . . . . . . . . . . .  54
     9.19. CBOR Tags Registry  . . . . . . . . . . . . . . . . . . .  54
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  54
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  54
     10.2.  Informative References . . . . . . . . . . . . . . . . .  56
   Appendix A.  Example C509 Certificates  . . . . . . . . . . . . .  59
     A.1.  Example RFC 7925 profiled X.509 Certificate . . . . . . .  59
     A.2.  Example IEEE 802.1AR profiled X.509 Certificate . . . . .  63
     A.3.  Example CAB Baseline ECDSA HTTPS X.509 Certificate  . . .  67
     A.4.  Example CAB Baseline RSA HTTPS X.509 Certificate  . . . .  69
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  72
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  72

1.  Introduction

   One of the challenges with deploying a Public Key Infrastructure
   (PKI) for the Internet of Things (IoT) is the size and parsing of
   X.509 public key certificates [RFC5280], since those are not
   optimized for constrained environments [RFC7228].  Large certificate
   chains are also problematic in non-constrained protocols such as EAP-
   TLS [RFC9190] [RFC9191] where authenticators typically drop an EAP
   session after only 40 - 50 round-trips, QUIC [RFC9000] where the
   latency increases significantly unless the server sends less than
   three times as many bytes as received prior to validating the client
   address, and RPKI [RFC6487] where a single certificate can be very
   large.  More compact certificate representations are therefore
   desirable in many use cases.  Due to the current PKI usage of DER
   encoded X.509 certificates, keeping compatibility with DER encoded
   X.509 is necessary at least for a transition period.  However, the
   use of a more compact encoding with the Concise Binary Object
   Representation (CBOR) [RFC8949] reduces the certificate size
   significantly which has known performance benefits in terms of

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   decreased communication overhead, power consumption, latency,
   storage, etc.  The use of CBOR also reduces code complexity, code
   size, memory usage, and CPU usage.

   CBOR is a data format designed for small code size and small message
   size.  CBOR builds on the JSON data model but extends it by e.g.
   encoding binary data directly without base64 conversion.  In addition
   to the binary CBOR encoding, CBOR also has a diagnostic notation that
   is readable and editable by humans.  The Concise Data Definition
   Language (CDDL) [RFC8610] provides a way to express structures for
   protocol messages and APIs that use CBOR.  RFC 8610 also extends the
   diagnostic notation.

   CBOR data items are encoded to or decoded from byte strings using a
   type-length-value encoding scheme, where the three highest order bits
   of the initial byte contain information about the major type.  CBOR
   supports several different types of data items, in addition to
   integers (int, uint), simple values (e.g. null), byte strings (bstr),
   and text strings (tstr), CBOR also supports arrays [] of data items,
   maps {} of pairs of data items, and sequences of data items.  For a
   complete specification and examples, see [RFC8949], [RFC8610], and
   [RFC8742].  We recommend implementors to get used to CBOR by using
   the CBOR playground [CborMe].

   CAB Baseline Requirements [CAB-TLS], RFC 7925 [RFC7925], IEEE 802.1AR
   [IEEE-802.1AR], and CNSA [RFC8603] specify certificate profiles which
   can be applied to certificate based authentication with, e.g., TLS
   [RFC8446], QUIC [RFC9000], DTLS [RFC9147], COSE [RFC9052], EDHOC
   [I-D.ietf-lake-edhoc], or Compact TLS 1.3 [I-D.ietf-tls-ctls].  RFC
   7925 [RFC7925], RFC7925bis [I-D.ietf-uta-tls13-iot-profile], and IEEE
   802.1AR [IEEE-802.1AR] specifically target Internet of Things
   deployments.  This document specifies a CBOR encoding based on
   [X.509-IoT], which can support large parts of RFC 5280.  The encoding
   supports all RFC 7925, IEEE 802.1AR, CAB Baseline [CAB-TLS],
   [CAB-Code], RPKI [RFC6487], eUICC [GSMA-eUICC] profiled X.509
   certificates, and is designed to render a compact encoding of
   certificates used in constrained environments.

   The resulting certificates are called C509 Certificates.  This
   document does not specify a certificate profile.  Two variants are
   defined using the same CBOR encoding and differing only in what is
   being signed:

   1.  An invertible CBOR re-encoding of DER encoded X.509 certificates
       [RFC5280], which can be reversed to obtain the original DER
       encoded X.509 certificate.

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   2.  Natively signed C509 certificates, where the signature is
       calculated over the CBOR encoding instead of over the DER
       encoding as in 1.  This removes the need for ASN.1 and DER
       parsing and the associated complexity but they are not backwards
       compatible with implementations requiring DER encoded X.509.

   Natively signed C509 certificates can be applied in devices that are
   only required to authenticate to natively signed C509 certificate
   compatible servers, which is not a major restriction for many IoT
   deployments where the parties issuing and verifying certificates can
   be a restricted ecosystem.

   This document also specifies C509 Certificate Signing Requests, see
   Section 4; COSE headers for use of the C509 certificates with COSE,
   see Section 9.12; and a TLS certificate type for use of the C509
   certificates with TLS and QUIC (with or without additional TLS
   certificate compression), see Section 9.18.

2.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   This specification makes use of the terminology in [RFC2986],
   [RFC5280], [RFC7228], [RFC8610], and [RFC8949].  When referring to
   CBOR, this specification always refers to Deterministically Encoded
   CBOR as specified in Sections 4.2.1 and 4.2.2 of [RFC8949].

3.  C509 Certificate

   This section specifies the content and encoding for C509
   certificates, with the overall objective to produce a very compact
   representation supporting large parts of [RFC5280], and everything in
   [RFC7925], [IEEE-802.1AR], RPKI [RFC6487], GSMA eUICC [GSMA-eUICC],
   and CAB Baseline [CAB-TLS] [CAB-Code].  In the CBOR encoding, static
   fields are elided, elliptic curve points and time values are
   compressed, OID are replaced with short integers or complemented with
   CBOR OID encoding [RFC9090], and redundant encoding is removed.
   Combining these different components reduces the certificate size
   significantly, which is not possible with general purpose compression
   algorithms, see Figure 5.

   The C509 certificate can be either a CBOR re-encoding of a DER
   encoded X.509 certificate, in which case the signature is calculated
   on the DER encoded ASN.1 data in the X.509 certificate, or a natively

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   signed C509 certificate, in which case the signature is calculated
   directly on the CBOR encoded data.  In both cases the certificate
   content is adhering to the restrictions given by [RFC5280].  The re-
   encoding is known to work with DER encoded certificates but might
   work with other canonical encodings.  The re-encoding does not work
   for BER encoded certificates.

   In the encoding described below, the order of elements in arrays are
   always encoded in the same order as the elements or the corresponding
   SEQUENCE or SET in the DER encoding.

3.1.  Message Fields

   The X.509 fields and their CBOR encodings are listed below, and used
   in the definition of C509 certificates, see Figure 1.

   C509 certificates are defined in terms of DER encoded [RFC5280] X.509
   certificates:

   *  version.  The 'version' field is encoded in the
      'c509CertificateType' CBOR int.  The field 'c509CertificateType'
      also indicates the type of the C509 certificate.  Currently, the
      type can be a natively signed C509 certificate following X.509 v3
      (c509CertificateType = 2) or a CBOR re-encoded X.509 v3 DER
      certificate (c509CertificateType = 3), see Section 9.1.

   *  serialNumber.  The 'serialNumber' INTEGER value field is encoded
      as the unwrapped CBOR unsigned bignum (~biguint)
      'certificateSerialNumber'.  Any leading 0x00 byte (to indicate
      that the number is not negative) is therefore omitted.

   *  signature.  The 'signature' field, containing the signature
      algorithm including parameters, is encoded as a CBOR int (see
      Section 9.10) or as an array with an unwrapped CBOR OID tag
      [RFC9090] optionally followed by the parameters encoded as a CBOR
      byte string.

   *  issuer.  In the general case, the sequence of 'Attribute' is
      encoded as a CBOR array of Attributes.  RelativeDistinguishedName
      with more than one AttributeTypeAndValue is not supported.  Each
      Attribute is encoded as either

      -  a (CBOR int, CBOR text string) pair, or

      -  a (unwrapped CBOR OID, CBOR bytes) pair.

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      The absolute value of the CBOR int (see Figure 8) encodes the
      attribute type and the sign is used to represent the character
      string type; positive for utf8String, negative for
      printableString.  The Attribute Email Address and domainComponent
      (as specified in [RFC3039]) are always an ia5String.  In natively
      signed C509 certificates all text strings are UTF-8 encoded and
      all attributeType SHALL be non-negative.  Text strings SHALL still
      adhere to any X.509 restrictions, i.e., serialNumber SHALL only
      contain the 74 character subset of ASCII allowed by
      printableString and countryName SHALL have length 2.  In re-
      encoded C509 certificates, attribute values of types ia5String (if
      this is the only allowed type, e.g. emailAddress), printableString
      and utf8String are allowed, and the string types teletexString,
      universalString, and bmpString are not supported.  If Name
      contains a single Attribute containing an utf8String encoded
      'common name' it is encoded as follows:

      -  If the text string has an even length ≥ 2 and contains only the
         symbols '0'–'9' or 'a'–'f', it is encoded as a CBOR byte
         string, prefixed with an initial byte set to '00'.

      -  If the text string contains an EUI-64 of the form "HH-HH-HH-HH-
         HH-HH-HH-HH" where 'H' is one of the symbols '0'–'9' or 'A'–'F'
         it is encoded as a CBOR byte string prefixed with an initial
         byte set to '01', for a total length of 9.  An EUI-64 mapped
         from a 48-bit MAC address (i.e., of the form "HH-HH-HH-FF-FE-
         HH-HH-HH) is encoded as a CBOR byte string prefixed with an
         initial byte set to '01', for a total length of 7.

      -  Otherwise it is encoded as a CBOR text string.

      If the 'issuer' field is identical to the 'subject' field, e.g. in
      case of self-signed certificates, then it MUST be encoded as CBOR
      null.

   *  validity.  The 'notBefore' and 'notAfter' fields are encoded as
      unwrapped CBOR epoch-based date/time (~time) where the tag content
      is an unsigned integer.  In POSIX time, leap seconds are ignored,
      with a leap second having the same POSIX time as the second before
      it.  Compression of X.509 certificates with the time 23:59:60 UTC
      is therefore not supported.  Note that RFC 5280 mandates encoding
      of dates through the year 2049 as UTCTime, and later dates as
      GeneralizedTime.  The value "99991231235959Z" (no expiration date)
      is encoded as CBOR null.

   *  subject.  The 'subject' field is encoded exactly like issuer,
      except that CBOR null is not a valid value.

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   *  subjectPublicKeyInfo.  The 'AlgorithmIdentifier' field including
      parameters is encoded as the CBOR int 'subjectPublicKeyAlgorithm'
      (see Section 9.11) or as an array with an unwrapped CBOR OID tag
      [RFC9090] optionally followed by the parameters encoded as a CBOR
      byte string.  In general, the 'subjectPublicKey' BIT STRING value
      field is encoded as a CBOR byte string.  This specification
      assumes the BIT STRING has zero unused bits and the unused bits
      byte is omitted.  For rsaEncryption and id-ecPublicKey, the
      encoding of subjectPublicKey is further optimized as described in
      Section 3.2.

   *  issuerUniqueID.  Not supported.

   *  subjectUniqueID.  Not supported.

   *  extensions.  The 'extensions' field is encoded as a CBOR array
      where each extension is encoded as either

      -  a CBOR int (see Section 9.4) followed by a CBOR item of any
         type, or

      -  an unwrapped CBOR OID tag [RFC9090] followed by an optional
         CBOR bool encoding 'critical' and the DER encoded value of the
         'extnValue' encoded as a CBOR byte string.

   If the array contains exactly two ints and the absolute value of the
   first int is 2 (corresponding to keyUsage), the array is omitted and
   the extensions is encoded as a single CBOR int with the absolute
   value of the second int and the sign of the first int.  Extensions
   are encoded as specified in Section 3.3.  The extensions mandated to
   be supported by [RFC7925] and [IEEE-802.1AR] are given special
   treatment.  An omitted 'extensions' field is encoded as an empty CBOR
   array.

   *  signatureAlgorithm.  The 'signatureAlgorithm' field is always the
      same as the 'signature' field and therefore omitted from the CBOR
      encoding.

   *  signatureValue.  In general, the 'signatureValue' BIT STRING value
      field is encoded as the CBOR byte string issuerSignatureValue.
      This specification assumes the BIT STRING has zero unused bits and
      the unused bits byte is omitted.  For natively signed C509
      certificates the signatureValue is calculated over the CBOR
      sequence TBSCertificate.  For ECDSA, the encoding of
      issuerSignatureValue is further optimized as described in
      Section 3.2

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   The following Concise Data Definition Language (CDDL) defines the
   CBOR array C509Certificate and the CBOR sequence [RFC8742]
   TBSCertificate.  The member names therefore only have documentary
   value.  Applications not requiring a CBOR item MAY represent C509
   certificates with the CBOR sequence ~C509Certificate (unwrapped
   C509Certificate).

    C509Certificate = [
       TBSCertificate,
       issuerSignatureValue : any,
    ]

    ; The elements of the following group are used in a CBOR Sequence:
    TBSCertificate = (
       c509CertificateType: int,
       certificateSerialNumber: CertificateSerialNumber,
       issuerSignatureAlgorithm: AlgorithmIdentifier,
       issuer: Name / null,
       validityNotBefore: ~time,
       validityNotAfter: ~time / null,
       subject: Name,
       subjectPublicKeyAlgorithm: AlgorithmIdentifier,
       subjectPublicKey: any,
       extensions: Extensions,
    )

    CertificateSerialNumber = ~biguint

    Name = [ * Attribute ] / text / bytes

    Attribute = ( attributeType: int, attributeValue: text ) //
                ( attributeType: ~oid, attributeValue: bytes )

    AlgorithmIdentifier = int / ~oid /
                        [ algorithm: ~oid, parameters: bytes ]

    Extensions = [ * Extension ] / int

    Extension = ( extensionID: int, extensionValue: any ) //
                ( extensionID: ~oid, ? critical: true,
                  extensionValue: bytes )

                    Figure 1: CDDL for C509Certificate.

3.2.  Encoding of subjectPublicKey and issuerSignatureValue

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3.2.1.  Encoding of subjectPublicKey

   For RSA public keys (rsaEncryption), the SEQUENCE and INTEGER type
   and length fields are omitted and the two INTEGER value fields
   (modulus, exponent) are encoded as an array of two unwrapped CBOR
   unsigned bignum (~biguint), i.e. [ modulus : ~biguint, exponent :
   ~biguint ].  If the exponent is 65537, the array and the exponent is
   omitted and subjectPublicKey consist of only the modulus encoded as
   an unwrapped CBOR unsigned bignum (~biguint).

   For elliptic curve public keys in Weierstraß form (id-ecPublicKey),
   keys may be point compressed as defined in Section 2.3.3 of [SECG].
   Native C509 certificates with Weierstraß form keys use the octets
   0x02, 0x03, and 0x04 as defined in [SECG].  If a DER encoded
   certificate with an uncompressed public key of type id-ecPublicKey is
   CBOR encoded with point compression, the octets 0xfe and 0xfd are
   used instead of 0x02 and 0x03 in the CBOR encoding to represent even
   and odd y-coordinate, respectively.

3.2.2.  Encoding of issuerSignatureValue

   For ECDSA signatures, the SEQUENCE and INTEGER type and length fields
   as well as the any leading 0x00 byte (to indicate that the number is
   not negative) are omitted.  If the two INTEGER value fields have
   different lengths, the shorter INTEGER value field is padded with
   zeroes so that the two fields have the same length.  The resulting
   byte string is encoded as a CBOR byte string.

3.3.  Encoding of Extensions

   This section details the encoding of the 'extensions' field.  The
   'extensions' field is encoded as a CBOR array where each extensionID
   is encoded either as a CBOR int or as an unwrapped CBOR OID tag.  If
   'extensionID' is encoded an int (see Section 9.4), the sign is used
   to encode if the extension is critical and the 'critical' field is
   omitted.  Critical extensions are encoded with a negative sign and
   non-critical extensions are encoded with a positive sign.

   The 'extnValue' OCTET STRING value field is encoded as the CBOR byte
   string 'extensionValue' except for the extensions specified below.
   For some extensions, only commonly used parts are supported by the
   CBOR encoding.  If unsupported parts are used, the CBOR encoding
   cannot be used.

   A note on extension ID naming: in existing OID databases most IDs can
   be found in versions with and without an 'id-pe' or 'id-ce' prefix.
   We have excluded the prefix for the commonly used extensions defined
   in [RFC5280] and included them for extensions defined elsewhere.

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   CBOR encoding of the following extension values is fully supported:

   *  Subject Key Identifier (subjectKeyIdentifier).  The extensionValue
      is encoded as follows:

      KeyIdentifier = bytes
      SubjectKeyIdentifier = KeyIdentifier

   *  Key Usage (keyUsage).  The 'KeyUsage' BIT STRING is interpreted as
      an unsigned integer in network byte order and encoded as a CBOR
      int.  See Section 3.1 for special encoding in case keyUsage is the
      only extension present.

      KeyUsage = int

   *  Policy Mappings (policyMappings). extensionValue is encoded as
      follows:

      PolicyMappings = [
        + (issuerDomainPolicy: ~oid, subjectDomainPolicy: ~oid)
      ]

   *  Basic Constraints (basicConstraints).  If 'cA' = false then
      extensionValue = -2, if 'cA' = true and 'pathLenConstraint' is not
      present then extensionValue = -1, and if 'cA' = true and
      'pathLenConstraint' is present then extensionValue =
      pathLenConstraint.

      BasicConstraints = int

   *  Policy Constraints (policyConstraints). extensionValue is encoded
      as follows:

      PolicyConstraints = [
        requireExplicitPolicy: uint / null,
        inhibitPolicyMapping: uint / null,
      ]

   *  Extended Key Usage (extKeyUsage). extensionValue is encoded as an
      array of CBOR ints (see Section 9.8), or unwrapped CBOR OID tags
      [RFC9090], where each int or OID encodes a key usage purpose.  If
      the array contains a single KeyPurposeId, the array is omitted.

      KeyPurposeId = int / ~oid
      ExtKeyUsageSyntax = [ 2* KeyPurposeId ] / KeyPurposeId

   *  Inhibit anyPolicy (inhibitAnyPolicy). extensionValue is encoded as
      follows:

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      InhibitAnyPolicy = uint

   CBOR encoding of the following extension values are partly supported:

   *  Subject Alternative Name (subjectAltName).  If the subject
      alternative name only contains general names registered in
      Section 9.9 the extension value can be CBOR encoded.
      extensionValue is encoded as an array of (int, any) pairs where
      each pair encodes a general name (see Section 9.9).  If
      subjectAltName contains exactly one dNSName, the array and the int
      are omitted and extensionValue is the dNSName encoded as a CBOR
      text string.  In addition to the general names defined in
      [RFC5280], the hardwareModuleName type of otherName has been given
      its own int due to its mandatory use in IEEE 802.1AR.  When
      'otherName + hardwareModuleName' is used, then [ ~oid, bytes ] is
      used to contain the pair ( hwType, hwSerialNum ) directly as
      specified in [RFC4108].  Only the general names in Section 9.9 are
      supported.

      GeneralName = ( GeneralNameType : int, GeneralNameValue : any )
      GeneralNames = [ + GeneralName ]
      SubjectAltName = GeneralNames / text

   *  Issuer Alternative Name (issuerAltName). extensionValue is encoded
      exactly like subjectAltName.

      IssuerAltName  = GeneralNames / text

   *  CRL Distribution Points (cRLDistributionPoints).  If the CRL
      Distribution Points is a sequence of DistributionPointName, where
      each DistributionPointName only contains
      uniformResourceIdentifiers, the extension value can be CBOR
      encoded. extensionValue is encoded as follows:

      DistributionPointName = [ 2* text ] / text
      CRLDistributionPoints = [ + DistributionPointName ]

   *  Freshest CRL (freshestCRL). extensionValue is encoded exactly like
      cRLDistributionPoints.

      FreshestCRL = CRLDistributionPoints

   *  Authority Information Access (authorityInfoAccess).  If all the
      GeneralNames in authorityInfoAccess are of type
      uniformResourceIdentifier, the extension value can be CBOR
      encoded.  Each accessMethod is encoded as a CBOR int (see
      Section 9.7) or an unwrapped CBOR OID tag [RFC9090].  The
      uniformResourceIdentifiers are encoded as CBOR text strings.

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      AccessDescription = ( accessMethod: int / ~oid , uri: text )
      AuthorityInfoAccessSyntax = [ + AccessDescription ]

   *  Subject Information Access (subjectInfoAccess).  Encoded exactly
      like authorityInfoAccess.

      SubjectInfoAccessSyntax = AuthorityInfoAccessSyntax

   *  Authority Key Identifier (authorityKeyIdentifier).  If the
      authority key identifier contains all of keyIdentifier,
      certIssuer, and certSerialNumberm or if only keyIdentifier is
      present the extension value can be CBOR encoded.  If all three are
      present a CBOR array is used, if only keyIdentifier is present,
      the array is omitted:

      KeyIdentifierArray = [
        keyIdentifier: KeyIdentifier,
        authorityCertIssuer: GeneralNames,
        authorityCertSerialNumber: CertificateSerialNumber
      ]
      AuthorityKeyIdentifier = KeyIdentifierArray / KeyIdentifier

   *  Certificate Policies (certificatePolicies).  If noticeRef is not
      used and any explicitText are encoded as UTF8String, the extension
      value can be CBOR encoded.  OIDs registered in Section 9.5 are
      encoded as an int.  The policyQualifierId is encoded as an CBOR
      int (see Section 9.6) or an unwrapped CBOR OID tag [RFC9090].

      PolicyIdentifier = int / ~oid
      PolicyQualifierInfo = (
        policyQualifierId: int / ~oid,
        qualifier: text,
      )
      CertificatePolicies = [
        + ( PolicyIdentifier, ? [ + PolicyQualifierInfo ] )
      ]

   *  Name Constraints (nameConstraints).  If the name constraints only
      contain general names registered in Section 9.9 the extension
      value can be CBOR encoded.  C509 uses the same additions and
      restrictions as defined in Section 4.2.1.10 of [RFC5280].  Note
      that the minimum and maximum fields are not used and therefore
      omitted.

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      GeneralSubtrees = [ + GeneralName ]
      NameConstraints = [
        permittedSubtrees: GeneralSubtrees / null,
        excludedSubtrees: GeneralSubtrees / null,
      ]

   *  Subject Directory Attributes (subjectDirectoryAttributes).
      Encoded as attributes in issuer and subject with the difference
      that there can be more than one attributeValue.

      Attributes = ( attributeType: int, attributeValue: [+text] ) //
                   ( attributeType: ~oid, attributeValue: [+bytes] )
      SubjectDirectoryAttributes = [+Attributes]

   *  AS Resources (id-pe-autonomousSysIds).  If rdi is not present, the
      extension value can be CBOR encoded.  Each ASId is encoded as an
      uint.  With the exception of the first ASId, the ASid is encoded
      as the difference to the previous ASid.

      ASIdOrRange = uint / [min:uint, max:uint]
      ASIdentifiers = [ + ASIdOrRange ] / null

   *  AS Resources v2 (id-pe-autonomousSysIds-v2).  Encoded exactly like
      autonomousSysIds.

   *  IP Resources (id-pe-ipAddrBlocks).  If rdi and SAFI is not
      present, the extension value can be CBOR encoded.  Each
      AddressPrefix is encoded as a CBOR bytes string (without the
      unused bits octet) followed by the number of unused bits encoded
      as a CBOR uint.  Each AddressRange is encoded as an array of two
      CBOR byte strings.  The unused bits for min and max are omitted,
      but the unused bits in max IPAddress is set to ones.  With the
      exception of the first Address, if the byte string has the same
      length as the previous Address, the Address is encoded as an uint
      with the the difference to the previous Address.  It should be
      noted that using address differences for compactness prevents
      encoding an address range larger than 2^64 - 1 corresponding to
      the cbor integer max value.

      Address = bytes / uint,
      AddressPrefix = (Address, unusedBits: uint)
      AddressRange =  [min:Address, max:Address]
      IPAddressOrRange = AddressPrefix / AddressRange
      IPAddressChoice = [ + IPAddressOrRange ] / null
      IPAddrBlocks = [ AFI: uint, IPAddressChoice ]

   *  IP Resources v2 (id-pe-ipAddrBlocks-v2).  Encoded exactly like id-
      pe-ipAddrBlocks.

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   *  Signed Certificate Timestamp.  If all the SCTs are version 1, and
      there are no SCT extensions, the extension value can be CBOR
      encoded.  LogIDs are encoded as CBOR byte strings, the timestamp
      is encoded as a CBOR int (milliseconds since validityNotBefore),
      and the signature is encoded with an (AlgorithmIdentifier, any)
      pair in the same way as issuerSignatureAlgorithm and
      issuerSignatureValue.

      SignedCertificateTimestamp = (
        logID: bytes,
        timestamp: int,
        sigAlg: AlgorithmIdentifier,
        sigValue: any,
      )
      SignedCertificateTimestamps = [ + SignedCerticateTimestamp ]

3.3.1.  Example Encoding of Extensions

   The examples below use values from Section 9.4, Section 9.8, and
   Section 9.9:

   *  A critical basicConstraints ('cA' = true) without
      pathLenConstraint is encoded as the two CBOR ints -4, -1.

   *  A non-critical keyUsage with digitalSignature (0), nonRepudiation
      (1), keyEncipherment (2) and keyAgreement (4) asserted is encoded
      as the two CBOR ints 2, 23 (2^0 + 2^1 + 2^2 + 2^4 = 23).

   *  A non-critical extKeyUsage containing id-kp-codeSigning and id-kp-
      OCSPSigning is encoded as the CBOR int 8 followed by the CBOR
      array [ 3, 9 ].

   *  A non-critical subjectAltName containing only the dNSName
      example.com is encoded as the CBOR int 3 followed by the CBOR text
      string "example.com".

   Thus, the extension field of a certificate containing all of the
   above extensions in the given order would be encoded as the CBOR
   array [ -4, -1, 2, 23, 8, [ 3, 9 ], 3, "example.com" ].

3.4.  COSE Header Parameters

   The formatting and processing for c5b, c5c, and c5t, and c5u, defined
   in Table 1 are similar to x5bag, x5chain, x5t, x5u defined in
   [RFC9360] except that the certificates are C509 instead of DER
   encoded X.509 and uses a COSE_C509 structure instead of COSE_X509.
   c5u provides an alternative way to identify an untrusted certificate
   bag/chain by reference with a URI.  The content is a COSE_C509 item

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   served with the application/cose-c509-cert media type, see
   Section 9.13, with corresponding CoAP Content-Format defined in
   Section 9.17.  A stored file format is defined in [RFC9277], with
   "magic number" TBD8 composed of the reserved CBOR tag 55799
   concatenated with the CBOR tag calculated from the CoAP Content-
   Format value.

   The COSE_C509 structure used in c5b, c5c, and c5u is defined as:

   COSE_C509 = C509Certificate / [ 2* C509Certificate ]

   As the contents of c5b, c5c, c5t, and c5u are untrusted input, the
   header parameters can be in either the protected or unprotected
   header bucket.  The trust mechanism MUST process any certificates in
   the c5b, c5c, and c5u parameters as untrusted input.  The presence of
   a self-signed certificate in the parameter MUST NOT cause the update
   of the set of trust anchors without some out-of-band confirmation.

      +======+=======+===============+=============================+
      | Name | Label | Value Type    | Description                 |
      +======+=======+===============+=============================+
      |  c5b | TBD1  | COSE_C509     | An unordered bag of C509    |
      |      |       |               | certificates                |
      +------+-------+---------------+-----------------------------+
      |  c5c | TBD2  | COSE_C509     | An ordered chain of C509    |
      |      |       |               | certificates                |
      +------+-------+---------------+-----------------------------+
      |  c5t | TBD3  | COSE_CertHash | Hash of a C509Certificate   |
      +------+-------+---------------+-----------------------------+
      |  c5u | TBD4  | uri           | URI pointing to a COSE_C509 |
      |      |       |               | containing a ordered chain  |
      |      |       |               | of certificates             |
      +------+-------+---------------+-----------------------------+

                     Table 1: COSE Header Parameters

   Note that certificates can also be identified with a 'kid' header
   parameter by storing 'kid' and the associated bag or chain in a
   dictionary.

3.5.  Private Key Structures

   Certificate management also makes use of data structures including
   private keys, see e.g.  [RFC7468].  This section defines the
   following CBOR encoded structures:

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   C509PrivateKey = [
      subjectPrivateKeyAlgorithm: AlgorithmIdentifier,
      subjectPrivateKey: any,
   ]

   The C509PrivateKey item is served with the application/cose-
   c509-privkey media type, see Section 9.15, with corresponding CoAP
   Content-Format defined in Section 9.17.  A stored file format is
   defined in [RFC9277], with "magic number" TBD12 composed of the
   reserved CBOR tag 55799 concatenated with the CBOR tag calculated
   from the CoAP Content-Format value.

   C509PEM = [
      C509PrivateKey,
      COSE_C509 / null,
   ]

   The C509PEM item is served with the application/cose-c509-pem media
   type, see Section 9.16, with corresponding CoAP Content-Format
   defined in Section 9.17.  A stored file format is defined in
   [RFC9277], with "magic number" TBD13 composed of the reserved CBOR
   tag 55799 concatenated with the CBOR tag calculated from the CoAP
   Content-Format value.

   Editor's note: Include further details for encoding of
   subjectPrivateKey.

4.  C509 Certificate Signing Request

   This section defines the format of a C509 Certificate Signing Request
   (CSR), also known as a C509 Certificate Request, based on and
   compatible with RFC 2986 [RFC2986], and reusing the formatting of
   C509 certificates defined in Section 3.  The media type is
   application/cose-c509-pkcs10, see Section 9.14, with corresponding
   CoAP Content-Format defined in Section 9.17.  The "magic number" TBD9
   is composed of the reserved CBOR tag 55799 concatenated with the CBOR
   tag calculated from the CoAP Content-Format value, see [RFC9277].

   Different types of C509 Certificate Requests are defined, see
   Section 9.2, all using the same CBOR encoding and differing only in
   what is being signed and what type of C509 certificate is being
   requested:

   *  The C509 Certificate Request can either be an invertible CBOR re-
      encoding of a DER encoded RFC 2986 certification request, or it
      can be natively signed where the signature is calculated over the
      CBOR encoding instead of the DER encoding.

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   *  The requested C509 certificate in the C509 Certificate Request can
      either be of type 2 or of type 3, see Section 9.1.

   Combining these options enables the four instances of
   c509CertificateRequestType defined in Section 9.2 and illustrated in
   Figure 2.

+------------------+---------------------------------------------------+
|                  |              Requested certificate                |
+------------------+=========================+=========================+
| Signed object    | c509CertificateType = 2 | c509CertificateType = 3 |
+==================+-------------------------+-------------------------+
|                  |                         |                         |
| CBOR encoded CSR |            0            |             2           |
|                  |                         |                         |
+------------------+-------------------------+-------------------------+
|                  |                         |                         |
| DER encoded CSR  |            1            |             3           |
|                  |                         |                         |
+------------------+-------------------------+-------------------------+

       Figure 2: C509 Certificate Request Types 0, 1, 2 and 3.

   An implementation MAY only support c509CertificateRequestType = 0.
   The most common variants are expected to be:

   *  c509CertificateRequestType = 0.  This type indicates that the C509
      Certificate Request is natively signed, and that the requested
      certificate format has c509CertificateType = 2.  This encoding
      removes the need for ASN.1 and DER parsing and re-encoding in the
      requesting party.

   *  c509CertificateRequestType = 3.  This type indicates that the C509
      Certificate Request is CBOR re-encoded RFC 2986 certification
      requests, and that the requested certificate formate has
      c509CertificateType = 3.  This encoding is backwards compatible
      with legacy RFC 2986 certification requests and X.509
      certificates, but enables a reduced transport overhead.

   subjectSignatureAlgorithm can be a signature algorithm or a non-
   signature proof-of-possession algorithm, e.g., as defined in
   [RFC6955].  In the latter case, the signature is replaced by a MAC
   and requires a public Diffie-Hellman key of the verifier distributed
   out-of-band.  Both kinds are listed in the C509 Signature Algorithms
   Registry, see Section 9.10.  Note that a key agreement key pair may
   be used with a signature algorithm in a certificate request, see
   Appendix A.1.3.

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   Certificate request attributes, i.e. attributes for use with
   certificate requests providing additional information about the
   subject of the certificate, are defined in Section 5.4 of [RFC2985].
   The attribute extensionRequest is supported with a dedicated element.
   Other certificate request attributes are included using the same
   Extensions structure as in extensionsRequest, both extensions and
   attributes are listed in the C509 Extensions Registry, see Figure 9.
   The only other certificate request attribute specified in this
   document is challengePassword which is defined for printableString or
   utf8String values and encoded as CBOR text string, except if the text
   string has an even length ≥ 2 and contains only the symbols '0'–'9'
   or 'a'–'f', in which case it is encoded as a CBOR byte string.  The
   sign of extensionID of challengePassword indicates the string type
   (instead the criticalness in other extensions): positive for
   utf8String and negative for printableString.  In the native
   certificate request (types 0 and 2), only utf8String is allowed.

    C509CertificateRequest = [
       TBSCertificateRequest,
       subjectSignatureValue: any,
    ]

    ; The elements of the following group are used in a CBOR Sequence:
    TBSCertificateRequest = (
       c509CertificateRequestType: int,
       subjectSignatureAlgorithm: AlgorithmIdentifier,
       subject: Name,
       subjectPublicKeyAlgorithm: AlgorithmIdentifier,
       subjectPublicKey: any,
       extensionsRequest: Extensions,
    )

    challengePassword: tstr / bstr

                 Figure 3: CDDL for C509CertificateRequest.

   After verifying the subjectSignatureValue, the CA MAY transform the
   C509CertificateRequest into a [RFC2986] CertificationRequestInfo for
   compatibility with existing procedures and code.

5.  C509 Processing and Certificate Issuance

   It is straightforward to integrate the C509 format into legacy X.509
   processing during certificate issuance.  C509 processing can be
   performed as an isolated function of the CA, or as a separate
   function trusted by the CA.

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   The Certificate Signing Request (CSR) format defined in Section 4
   follows the PKCS#10 format to enable a direct mapping to the
   certification request information, see Section 4.1 of [RFC2986].

   When a certificate request is received, the CA, or function trusted
   by the CA, needs to perform some limited C509 processing and verify
   the proof-of-possession corresponding to the public key, before
   normal certificate generation can take place.

   In the reverse direction, in case c509CertificateType = 3 was
   requested, a separate C509 processing function can perform the
   conversion from a generated X.509 certificate to C509 as a bump-in-
   the-wire.  In case c509CertificateType = 2 was requested, the C509
   processing needs to be performed before signing the certificate, in
   which case a tighter integration with the CA may be needed.

6.  Legacy Considerations

   C509 certificates can be deployed with legacy X.509 certificates and
   CA infrastructure.  An existing CA can continue to use its existing
   procedures and code for PKCS#10, and DER encoded X.509 and only
   implement C509 as a thin processing layer on top.  When receiving a
   C509 CSR, the CA transforms it into a DER encoded RFC 2986
   CertificationRequestInfo and use that with existing processes and
   code to produce an RFC 5280 DER encoded X.509 certificate.  The DER
   encoded X.509 is then transformed into a C509 certificate.  At any
   later point, the C509 certificate can be used to recreate the
   original X.509 data structure needed to verify the signature.

   For protocols like TLS/DTLS 1.2, where the handshake is sent
   unencrypted, the actual encoding and compression can be done at
   different locations depending on the deployment setting.  For
   example, the mapping between C509 certificate and standard X.509
   certificate can take place in a 6LoWPAN border gateway which allows
   the server side to stay unmodified.  This case gives the advantage of
   the low overhead of a C509 certificate over a constrained wireless
   links.  The conversion to X.509 within an IoT device will incur a
   computational overhead, however, measured in energy this is likely to
   be negligible compared to the reduced communication overhead.

   For the setting with constrained server and server-only
   authentication, the server only needs to be provisioned with the C509
   certificate and does not perform the conversion to X.509.  This
   option is viable when client authentication can be asserted by other
   means.

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   For protocols like IKEv2, TLS/DTLS 1.3, and EDHOC, where certificates
   are encrypted, the proposed encoding needs to be done fully end-to-
   end, through adding the encoding/decoding functionality to the
   server.

7.  Expected Certificate Sizes

   The CBOR encoding of the sample certificate chains given in
   Appendix A results in the numbers shown in Figure 4 and Figure 5.
   COSE_X509 is defined in [RFC9360] and COSE_C509 is defined in
   Section 9.12.  After RFC 7925 profiling, most duplicated information
   has been removed, and the remaining text strings are minimal in size.
   Therefore, the further size reduction reached with general
   compression mechanisms such as Brotli will be small, mainly
   corresponding to making the ASN.1 encoding more compact.  CBOR
   encoding can however significantly compress RFC 7925 profiled
   certificates.  For the example HTTPS certificate chains (www.ietf.org
   and tools.ietf.org) both C509 and Brotli perform well complementing
   each other.  C509 use dedicated information to compress individual
   certificates, while Brotli can compress duplicate information in the
   entire chain.  Note that C509 certificates of type 2 and 3 have the
   same size.  For Brotli [RFC7932], the Rust crate Brotli 3.3.0 was
   used with compression level 11 and window size 22.

     +---------------------------------------+-----------+-----------+
     |                                       | COSE_X509 | COSE_C509 |
     +---------------------------------------+-----------+-----------+
     | RFC 7925 profiled IoT Certificate (1) |       317 |       139 |
     +---------------------------------------+-----------+-----------+
     | ECDSA HTTPS Certificate Chain (2)     |      2193 |      1394 |
     +---------------------------------------+-----------+-----------+
     | RSA HTTPS Certificate Chain (4)       |      5175 |      3934 |
     +---------------------------------------+-----------+-----------+

      Figure 4: Comparing Sizes of Certificate Chains in COSE.  Number
                  of bytes (length of certificate chain).

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   +-------------------+-------+----------------+------+---------------+
   |                   | X.509 | X.509 + Brotli | C509 | C509 + Brotli |
   +-------------------+-------+----------------+------+---------------+
   | RFC 7925 Cert (1) |   327 |            324 |  151 |           167 |
   +-------------------+-------+----------------+------+---------------+
   | RPKI Cert (1)     | 20991 |           9134 | 8660 |          5668 |
   +-------------------+-------+----------------+------+---------------+
   | HTTPS Chain (2)   |  2204 |           1455 | 1414 |          1063 |
   +-------------------+-------+----------------+------+---------------+
   | HTTPS Chain (4)   |  5190 |           3244 | 3958 |          2845 |
   +-------------------+-------+----------------+------+---------------+
   | HTTPS Bag (8)     | 11578 |           3979 | 8882 |          3519 |
   +-------------------+-------+----------------+------+---------------+

     Figure 5: Comparing Sizes of Certificate Chains with TLS.  Number
        of bytes (length of certificate chain).  X.509 and C509 are
        Certificate messages.  X.509 + Brotli and C509 + Brotli are
                      CompressedCertificate messages.

8.  Security Considerations

   The CBOR profiling of X.509 certificates does not change the security
   assumptions needed when deploying standard X.509 certificates but
   decreases the number of fields transmitted, which reduces the risk
   for implementation errors.

   The use of natively signed C509 certificates removes the need for
   ASN.1 encoding, which is a rich source of security vulnerabilities.

   Conversion between the certificate formats can be made in constant
   time to reduce risk of information leakage through side channels.

   The mechanism in this draft does not reveal any additional
   information compared to X.509.  Because of difference in size, it
   will be possible to detect that this profile is used.  The gateway
   solution described in Section 6 requires unencrypted certificates and
   is not recommended.

9.  IANA Considerations

   This document creates several new registries under the new heading
   "CBOR Encoded X.509 (C509) Parameters".  For all items, the
   'Reference' field points to this document.

   The expert reviewers for the registries defined in this document are
   expected to ensure that the usage solves a valid use case that could
   not be solved better in a different way, that it is not going to
   duplicate one that is already registered, and that the registered

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   point is likely to be used in deployments.  They are furthermore
   expected to check the clarity of purpose and use of the requested
   code points.  Experts should take into account the expected usage of
   entries when approving point assignment, and the length of the
   encoded value should be weighed against the number of code points
   left that encode to that size and how constrained the systems it will
   be used on are.  Values in the interval [-24, 23] have a 1 byte
   encodings, other values in the interval [-256, 255] have a 2 byte
   encodings, and the remaining values in the interval [-65536, 65535]
   have 3 byte encodings.

9.1.  C509 Certificate Types Registry

   IANA has created a new registry titled "C509 Certificate Types" under
   the new heading "CBOR Encoded X.509 (C509) Parameters".  The columns
   of the registry are Value, Description, and Reference, where Value is
   an integer, and the other columns are text strings.  For values in
   the interval [-24, 23] the registration procedure is "IETF Review"
   and "Expert Review".  For all other values the registration procedure
   is "Expert Review".  The initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Description                                               |
   +=======+===========================================================+
   |     0 | Reserved                                                  |
   +-------+-----------------------------------------------------------+
   |     1 | Reserved                                                  |
   +-------+-----------------------------------------------------------+
   |     2 | Natively Signed C509 Certificate following X.509 v3       |
   +-------+-----------------------------------------------------------+
   |     3 | CBOR re-encoding of X.509 v3 Certificate                  |
   +-------+-----------------------------------------------------------+

                      Figure 6: C509 Certificate Types

9.2.  C509 Certificate Request Types Registry

   IANA has created a new registry titled "C509 Certificate Request
   Types" under the new heading "CBOR Encoded X.509 (C509) Parameters".
   The columns of the registry are Value, Description, and Reference,
   where Value is an integer, and the other columns are text strings.
   For values in the interval [-24, 23] the registration procedure is
   "IETF Review" and "Expert Review".  For all other values the
   registration procedure is "Expert Review".  The initial contents of
   the registry are:

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   +-------+-----------------------------------------------------------+
   | Value | Description                                               |
   +=======+===========================================================+
   |     0 | Requested certificate is C509 Type 2.                     |
   |       | Natively Signed C509 Certificate Request.                 |
   +-------+-----------------------------------------------------------+
   |     1 | Requested certificate is C509 Type 2.                     |
   |       | CBOR re-encoding of RFC 2986 certification request.       |
   +-------+-----------------------------------------------------------+
   |     2 | Requested certificate is C509 Type 3.                     |
   |       | Natively Signed C509 Certificate Request.                 |
   +-------+-----------------------------------------------------------+
   |     3 | Requested certificate is C509 Type 3.                     |
   |       | CBOR re-encoding of RFC 2986 certification request.       |
   +-------+-----------------------------------------------------------+

                  Figure 7: C509 Certificate Request Types

9.3.  C509 Attributes Registry

   IANA has created a new registry titled "C509 Attributes" under the
   new heading "CBOR Encoded X.509 (C509) Parameters".  The columns of
   the registry are Value, Name, Identifiers, OID, DER, Comments, and
   Reference, where Value is an non-negative integer, and the other
   columns are text strings.  For values in the interval [0, 23] the
   registration procedure is "IETF Review" and "Expert Review".  Values
   ≥ 32768 are reserved for Private Use. For all other values the
   registration procedure is "Expert Review".  The initial contents of
   the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Attribute                                                 |
   +=======+===========================================================+
   |     0 | Name:            Email Address                            |
   |       | Identifiers:     emailAddress, e-mailAddress              |
   |       | OID:             1.2.840.113549.1.9.1                     |
   |       | DER:             06 09 2A 86 48 86 F7 0D 01 09 01         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            Common Name                              |
   |       | Identifiers:     commonName, cn                           |
   |       | OID:             2.5.4.3                                  |
   |       | DER:             06 03 55 04 03                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Surname                                  |
   |       | Identifiers:     surname, sn                              |
   |       | OID:             2.5.4.4                                  |

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   |       | DER:             06 03 55 04 04                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Serial Number                            |
   |       | Identifiers:     serialNumber                             |
   |       | OID:             2.5.4.5                                  |
   |       | DER:             06 03 55 04 05                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            Country                                  |
   |       | Identifiers:     countryName, c                           |
   |       | OID:             2.5.4.6                                  |
   |       | DER:             06 03 55 04 06                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            Locality                                 |
   |       | Identifiers:     localityName, locality, l                |
   |       | OID:             2.5.4.7                                  |
   |       | DER:             06 03 55 04 07                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            State or Province                        |
   |       | Identifiers:     stateOrProvinceName, st                  |
   |       | OID:             2.5.4.8                                  |
   |       | DER:             06 03 55 04 08                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Street Address                           |
   |       | Identifiers:     streetAddress, street                    |
   |       | OID:             2.5.4.9                                  |
   |       | DER:             06 03 55 04 09                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Organization                             |
   |       | Identifiers:     organizationName, o                      |
   |       | OID:             2.5.4.10                                 |
   |       | DER:             06 03 55 04 0A                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     9 | Name:            Organizational Unit                      |
   |       | Identifiers:     organizationalUnitName, ou               |
   |       | OID:             2.5.4.11                                 |
   |       | DER:             06 03 55 04 0B                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            Title                                    |
   |       | Identifiers:     title                                    |
   |       | OID:             2.5.4.12                                 |

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   |       | DER:             06 03 55 04 0C                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    11 | Name:            Business Category                        |
   |       | Identifiers:     businessCategory                         |
   |       | OID:             2.5.4.15                                 |
   |       | DER:             06 03 55 04 0F                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    12 | Name:            Postal Code                              |
   |       | Identifiers:     postalCode                               |
   |       | OID:             2.5.4.17                                 |
   |       | DER:             06 03 55 04 11                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:            Given Name                               |
   |       | Identifiers:     givenName                                |
   |       | OID:             2.5.4.42                                 |
   |       | DER:             06 03 55 04 2A                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14 | Name:            Initials                                 |
   |       | Identifiers:     initials                                 |
   |       | OID:             2.5.4.43                                 |
   |       | DER:             06 03 55 04 2B                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    15 | Name:            Generation Qualifier                     |
   |       | Identifiers:     generationQualifier                      |
   |       | OID:             2.5.4.44                                 |
   |       | DER:             06 03 55 04 2C                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    16 | Name:            DN Qualifier                             |
   |       | Identifiers:     dnQualifier                              |
   |       | OID:             2.5.4.46                                 |
   |       | DER:             06 03 55 04 2E                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    17 | Name:            Pseudonym                                |
   |       | Identifiers:     pseudonym                                |
   |       | OID:             2.5.4.65                                 |
   |       | DER:             06 03 55 04 41                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    18 | Name:            Organization Identifier                  |
   |       | Identifiers:     organizationIdentifier                   |
   |       | OID:             2.5.4.97                                 |

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   |       | DER:             06 03 55 04 61                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    19 | Name:            Inc. Locality                            |
   |       | Identifiers:     jurisdictionOfIncorporationLocalityName  |
   |       | OID:             1.3.6.1.4.1.311.60.2.1.1                 |
   |       | DER:             06 0B 2B 06 01 04 01 82 37 3C 02 01 01   |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    20 | Name:            Inc. State or Province                   |
   |       | Identifiers:     jurisdictionOfIncorporation              |
   |       |                  StateOrProvinceName                      |
   |       | OID:             1.3.6.1.4.1.311.60.2.1.2                 |
   |       | DER:             06 0B 2B 06 01 04 01 82 37 3C 02 01 02   |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    21 | Name:            Inc. Country                             |
   |       | Identifiers:     jurisdictionOfIncorporationCountryName   |
   |       | OID:             1.3.6.1.4.1.311.60.2.1.3                 |
   |       | DER:             06 0B 2B 06 01 04 01 82 37 3C 02 01 03   |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    22 | Name:            Domain Component                         |
   |       | Identifiers:     domainComponent, dc                      |
   |       | OID:             0.9.2342.19200300.100.1.25               |
   |       | DER:             06 0A 09 92 26 89 93 F2 2C 64 01 19      |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    24 | Name:            Postal Address                           |
   |       | Identifiers:     postalAddress                            |
   |       | OID:             2.5.4.16                                 |
   |       | DER:             06 03 55 04 10                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    25 | Name:            Name                                     |
   |       | Identifiers:     name                                     |
   |       | OID:             2.5.4.41                                 |
   |       | DER:             06 03 55 04 29                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    26 | Name:            Telephone Number                         |
   |       | Identifiers:     telephoneNumber                          |
   |       | OID:             2.5.4.20                                 |
   |       | DER:             06 03 55 04 14                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    27 | Name:            Directory Management Domain Name         |
   |       | Identifiers:     dmdName                                  |

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   |       | OID:             2.5.4.54                                 |
   |       | DER:             06 03 55 04 36                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    28 | Name:            userid                                   |
   |       | Identifiers:     uid                                      |
   |       | OID:             0.9.2342.19200300.100.1.1                |
   |       | DER:             06 0A 09 92 26 89 93 F2 2C 64 01 01      |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    29 | Name:            Unstructured Name                        |
   |       | Identifiers:     unstructuredName                         |
   |       | OID:             1.2.840.113549.1.9.2                     |
   |       | DER:             06 09 2A 86 48 86 F7 0D 01 09 02         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    30 | Name:            Unstructured Address                     |
   |       | Identifiers:     unstructuredAddress                      |
   |       | OID:             1.2.840.113549.1.9.8                     |
   |       | DER:             06 0A 2A 86 48 86 F7 0D 01 09 08 00      |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                         Figure 8: C509 Attributes

9.4.  C509 Extensions Registry

   IANA has created a new registry titled "C509 Extensions Registry"
   under the new heading "CBOR Encoded X.509 (C509) Parameters".  The
   columns of the registry are Value, Name, Identifiers, OID, DER,
   Comments, extensionValue, and Reference, where Value is an positive
   integer, and the other columns are text strings.  The registry also
   contains CSR attributes for use in Certificate Requests, see
   Section 4.  For values in the interval [1, 23] the registration
   procedure is "IETF Review" and "Expert Review".  Values ≥ 32768 are
   reserved for Private Use. For all other values the registration
   procedure is "Expert Review".  The initial contents of the registry
   are:

   +-------+-----------------------------------------------------------+
   | Value | Extension                                                 |
   +=======+===========================================================+
   |     1 | Name:            Subject Key Identifier                   |
   |       | Identifiers:     subjectKeyIdentifier                     |
   |       | OID:             2.5.29.14                                |
   |       | DER:             06 03 55 1D 0E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectKeyIdentifier                     |

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   +-------+-----------------------------------------------------------+
   |     2 | Name:            Key Usage                                |
   |       | Identifiers:     keyUsage                                 |
   |       | OID:             2.5.29.15                                |
   |       | DER:             06 03 55 1D 0F                           |
   |       | Comments:                                                 |
   |       | AttributeValue:  KeyUsage                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Subject Alternative Name                 |
   |       | Identifiers:     subjectAltName                           |
   |       | OID:             2.5.29.17                                |
   |       | DER:             06 03 55 1D 11                           |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectAltName                           |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            Basic Constraints                        |
   |       | Identifiers:     basicConstraints                         |
   |       | OID:             2.5.29.19                                |
   |       | DER:             06 03 55 1D 13                           |
   |       | Comments:                                                 |
   |       | extensionValue:  BasicConstraints                         |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            CRL Distribution Points                  |
   |       | Identifiers:     cRLDistributionPoints                    |
   |       | OID:             2.5.29.31                                |
   |       | DER:             06 03 55 1D 1F                           |
   |       | Comments:                                                 |
   |       | extensionValue:  CRLDistributionPoints                    |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            Certificate Policies                     |
   |       | Identifiers:     certificatePolicies                      |
   |       | OID:             2.5.29.32                                |
   |       | DER:             06 03 55 1D 20                           |
   |       | Comments:                                                 |
   |       | extensionValue:  CertificatePolicies                      |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Authority Key Identifier                 |
   |       | Identifiers:     authorityKeyIdentifier                   |
   |       | OID:             2.5.29.35                                |
   |       | DER:             06 03 55 1D 23                           |
   |       | Comments:                                                 |
   |       | extensionValue:  AuthorityKeyIdentifier                   |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Extended Key Usage                       |
   |       | Identifiers:     extKeyUsage                              |
   |       | OID:             2.5.29.37                                |
   |       | DER:             06 03 55 1D 25                           |
   |       | Comments:                                                 |

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   |       | extensionValue:  ExtKeyUsageSyntax                        |
   +-------+-----------------------------------------------------------+
   |     9 | Name:            Authority Information Access             |
   |       | Identifiers:     authorityInfoAccess                      |
   |       | OID:             1.3.6.1.5.5.7.1.1                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 01            |
   |       | Comments:                                                 |
   |       | extensionValue:  AuthorityInfoAccessSyntax                |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            Signed Certificate Timestamp List        |
   |       | Identifiers:                                              |
   |       | OID:             1.3.6.1.4.1.11129.2.4.2                  |
   |       | DER:             06 0A 2B 06 01 04 01 D6 79 02 04 02      |
   |       | Comments:                                                 |
   |       | extensionValue:  SignedCertificateTimestampList           |
   +-------+-----------------------------------------------------------+
   |    24 | Name:            Subject Directory Attributes             |
   |       | Identifiers:     subjectDirectoryAttributes               |
   |       | OID:             2.5.29.9                                 |
   |       | DER:             06 03 55 1D 09                           |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectDirectoryAttributes               |
   +-------+-----------------------------------------------------------+
   |    25 | Name:            Issuer Alternative Name                  |
   |       | Identifiers:     issuerAltName                            |
   |       | OID:             2.5.29.18                                |
   |       | DER:             06 03 55 1D 12                           |
   |       | Comments:                                                 |
   |       | extensionValue:  IssuerAltName                            |
   +-------+-----------------------------------------------------------+
   |    26 | Name:            Name Constraints                         |
   |       | Identifiers:     nameConstraints                          |
   |       | OID:             2.5.29.30                                |
   |       | DER:             06 03 55 1D 1E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  NameConstraints                          |
   +-------+-----------------------------------------------------------+
   |    27 | Name:            Policy Mappings                          |
   |       | Identifiers:     policyMappings                           |
   |       | OID:             2.5.29.33                                |
   |       | DER:             06 03 55 1D 21                           |
   |       | Comments:                                                 |
   |       | extensionValue:  PolicyMappings                           |
   +-------+-----------------------------------------------------------+
   |    28 | Name:            Policy Constraints                       |
   |       | Identifiers:     policyConstraints                        |
   |       | OID:             2.5.29.36                                |
   |       | DER:             06 03 55 1D 24                           |

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   |       | Comments:                                                 |
   |       | extensionValue:  PolicyConstraints                        |
   +-------+-----------------------------------------------------------+
   |    29 | Name:            Freshest CRL                             |
   |       | Identifiers:     freshestCRL                              |
   |       | OID:             2.5.29.46                                |
   |       | DER:             06 03 55 1D 2E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  FreshestCRL                              |
   +-------+-----------------------------------------------------------+
   |    30 | Name:            Inhibit anyPolicy                        |
   |       | Identifiers:     inhibitAnyPolicy                         |
   |       | OID:             2.5.29.54                                |
   |       | DER:             06 03 55 1D 36                           |
   |       | Comments:                                                 |
   |       | extensionValue:  InhibitAnyPolicy                         |
   +-------+-----------------------------------------------------------+
   |    31 | Name:            Subject Information Access               |
   |       | Identifiers:     subjectInfoAccess                        |
   |       | OID:             1.3.6.1.5.5.7.1.11                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 0B            |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectInfoAccessSyntax                  |
   +-------+-----------------------------------------------------------+
   |    32 | Name:            IP Resources                             |
   |       | Identifiers:     id-pe-ipAddrBlocks                       |
   |       | OID:             1.3.6.1.5.5.7.1.7                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 07            |
   |       | Comments:                                                 |
   |       | extensionValue:  IPAddrBlocks                             |
   +-------+-----------------------------------------------------------+
   |    33 | Name:            AS Resources                             |
   |       | Identifiers:     id-pe-autonomousSysIds                   |
   |       | OID:             1.3.6.1.5.5.7.1.8                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 08            |
   |       | Comments:                                                 |
   |       | extensionValue:  ASIdentifiers                            |
   +-------+-----------------------------------------------------------+
   |    34 | Name:            IP Resources v2                          |
   |       | Identifiers:     id-pe-ipAddrBlocks-v2                    |
   |       | OID:             1.3.6.1.5.5.7.1.28                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 1C            |
   |       | Comments:                                                 |
   |       | extensionValue:  IPAddrBlocks                             |
   +-------+-----------------------------------------------------------+
   |    35 | Name:            AS Resources v2                          |
   |       | Identifiers:     id-pe-autonomousSysIds-v2                |
   |       | OID:             1.3.6.1.5.5.7.1.29                       |

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   |       | DER:             06 08 2B 06 01 05 05 07 01 1D            |
   |       | Comments:                                                 |
   |       | extensionValue:  ASIdentifiers                            |
   +-------+-----------------------------------------------------------+
   |    36 | Name:            Biometric Information                    |
   |       | Identifiers:     id-pe-biometricInfo                      |
   |       | OID:             1.3.6.1.5.5.7.1.2                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 02            |
   |       | Comments:                                                 |
   |       | extensionValue:                                           |
   +-------+-----------------------------------------------------------+
   |    37 | Name:            Precertificate Signing Certificate       |
   |       | Identifiers:                                              |
   |       | OID:             1.3.6.1.4.1.11129.2.4.4                  |
   |       | DER:             06 0A 2B 06 01 04 01 D6 79 02 04 04      |
   |       | Comments:                                                 |
   |       | extensionValue:                                           |
   +-------+-----------------------------------------------------------+
   |    38 | Name:            OCSP No Check                            |
   |       | Identifiers:     id-pkix-ocsp-nocheck                     |
   |       | OID:             1.3.6.1.5.5.7.48.1.5                     |
   |       | DER:             06 09 2B 06 01 05 05 07 30 01 05         |
   |       | Comments:                                                 |
   |       | extensionValue:                                           |
   +-------+-----------------------------------------------------------+
   |    39 | Name:            Qualified Certificate Statements         |
   |       | Identifiers:     id-pe-qcStatements                       |
   |       | OID:             1.3.6.1.5.5.7.1.3                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 03            |
   |       | Comments:                                                 |
   |       | extensionValue:                                           |
   +-------+-----------------------------------------------------------+
   |    40 | Name:            S/MIME Capabilities                      |
   |       | Identifiers:     smimeCapabilities                        |
   |       | OID:             1.2.840.113549.1.9.15                    |
   |       | DER:             06 09 2A 86 48 86 F7 0D 01 09 0F         |
   |       | Comments:                                                 |
   |       | extensionValue:                                           |
   +-------+-----------------------------------------------------------+
   |    41 | Name:            TLS Features                             |
   |       | Identifiers:     id-pe-tlsfeature                         |
   |       | OID:             1.3.6.1.5.5.7.1.24                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 18            |
   |       | Comments:                                                 |
   |       | extensionValue:                                           |
   +-------+-----------------------------------------------------------+
   |   255 | Name:            Challenge Password                       |
   |       | Identifiers:     challengePassword                        |

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   |       | OID:             1.2.840.113549.1.9.7                     |
   |       | DER:             06 09 2A 86 48 86 F7 0D 01 09 07         |
   |       | Comments:        CSR Attribute                            |
   |       | extensionValue:  ChallengePassword                        |
   +-------+-----------------------------------------------------------+

                Figure 9: C509 Extensions and CSR Attributes

9.5.  C509 Certificate Policies Registry

   IANA has created a new registry titled "C509 Certificate Policies
   Registry" under the new heading "CBOR Encoded X.509 (C509)
   Parameters".  The columns of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  For values in the
   interval [-24, 23] the registration procedure is "IETF Review" and
   "Expert Review".  Values ≥ 32768 are reserved for Private Use. For
   all other values the registration procedure is "Expert Review".  The
   initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Certificate Policy                                        |
   +=======+===========================================================+
   |     0 | Name:            Any Policy                               |
   |       | Identifiers:     anyPolicy                                |
   |       | OID:             2.5.29.32.0                              |
   |       | DER:             06 04 55 1D 20 00                        |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            Domain Validation (DV)                   |
   |       | Identifiers:     domain-validated                         |
   |       | OID:             2.23.140.1.2.1                           |
   |       | DER:             06 06 67 81 0C 01 02 01                  |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Organization Validation (OV)             |
   |       | Identifiers:     organization-validated                   |
   |       | OID:             2.23.140.1.2.2                           |
   |       | DER:             06 06 67 81 0C 01 02 02                  |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Individual Validation (IV)               |
   |       | Identifiers:     individual-validated                     |
   |       | OID:             2.23.140.1.2.3                           |
   |       | DER:             06 06 67 81 0C 01 02 03                  |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            Extended Validation (EV)                 |

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   |       | Identifiers:     ev-guidelines                            |
   |       | OID:             2.23.140.1.1                             |
   |       | DER:             06 05 67 81 0C 01 01                     |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Resource PKI (RPKI)                      |
   |       | Identifiers:     id-cp-ipAddr-asNumber                    |
   |       | OID:             1.3.6.1.5.5.7.14.2                       |
   |       | DER:             06 08 2B 06 01 05 05 07 0E 02            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Resource PKI (RPKI) (Alternative)        |
   |       | Identifiers:     id-cp-ipAddr-asNumber-v2                 |
   |       | OID:             1.3.6.1.5.5.7.14.3                       |
   |       | DER:             06 08 2B 06 01 05 05 07 0E 03            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            Remote SIM Provisioning Role             |
   |       |                  Certificate Issuer                       |
   |       | Identifiers:     id-rspRole-ci                            |
   |       | OID:             2.23.146.1.2.1.0                         |
   |       | DER:             06 07 67 81 12 01 02 01 00               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    11 | Name:            Remote SIM Provisioning Role             |
   |       |                  eUICC                                    |
   |       | Identifiers:     id-rspRole-euicc                         |
   |       | OID:             2.23.146.1.2.1.1                         |
   |       | DER:             06 07 67 81 12 01 02 01 01               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    12 | Name:            Remote SIM Provisioning Role             |
   |       |                  eUICC Manufacturer                       |
   |       | Identifiers:     id-rspRole-eum                           |
   |       | OID:             2.23.146.1.2.1.2                         |
   |       | DER:             06 07 67 81 12 01 02 01 02               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DP+ TLS                               |
   |       | Identifiers:     id-rspRole-dp-tls                        |
   |       | OID:             2.23.146.1.2.1.3                         |
   |       | DER:             06 07 67 81 12 01 02 01 03               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DP+ Authentication                    |
   |       | Identifiers:     id-rspRole-dp-auth                       |

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   |       | OID:             2.23.146.1.2.1.4                         |
   |       | DER:             06 07 67 81 12 01 02 01 04               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    15 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DP+ Profile Binding                   |
   |       | Identifiers:     id-rspRole-dp-pb                         |
   |       | OID:             2.23.146.1.2.1.5                         |
   |       | DER:             06 07 67 81 12 01 02 01 05               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    16 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DS TLS                                |
   |       | Identifiers:     id-rspRole-ds-tls                        |
   |       | OID:             2.23.146.1.2.1.6                         |
   |       | DER:             06 07 67 81 12 01 02 01 06               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    17 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DS Authentication                     |
   |       | Identifiers:     id-rspRole-ds-auth                       |
   |       | OID:             2.23.146.1.2.1.7                         |
   |       | DER:             06 07 67 81 12 01 02 01 07               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                    Figure 10: C509 Certificate Policies

9.6.  C509 Policies Qualifiers Registry

   IANA has created a new registry titled "C509 Policies Qualifiers
   Registry" under the new heading "CBOR Encoded X.509 (C509)
   Parameters".  The columns of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  For values in the
   interval [-24, 23] the registration procedure is "IETF Review" and
   "Expert Review".  Values ≥ 32768 are reserved for Private Use. For
   all other values the registration procedure is "Expert Review".  The
   initial contents of the registry are:

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   +-------+-----------------------------------------------------------+
   | Value | Certificate Policy                                        |
   +=======+===========================================================+
   |     1 | Name:            Certification Practice Statement         |
   |       | Identifiers:     id-qt-cps, cps                           |
   |       | OID:             1.3.6.1.5.5.7.2.1                        |
   |       | DER:             06 08 2B 06 01 05 05 07 02 01            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            User Notice                              |
   |       | Identifiers:     id-qt-unotice, unotice                   |
   |       | OID:             1.3.6.1.5.5.7.2.2                        |
   |       | DER:             06 08 2B 06 01 05 05 07 02 02            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                    Figure 11: C509 Policies Qualifiers

9.7.  C509 Information Access Registry

   IANA has created a new registry titled "C509 Information Access
   Registry" under the new heading "CBOR Encoded X.509 (C509)
   Parameters".  The columns of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  For values in the
   interval [-24, 23] the registration procedure is "IETF Review" and
   "Expert Review".  For all other values the registration procedure is
   "Expert Review".  The initial contents of the registry are:

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   +-------+-----------------------------------------------------------+
   | Value | Information Access                                        |
   +=======+===========================================================+
   |     1 | Name:            OCSP                                     |
   |       | Identifiers:     id-ad-ocsp, id-pkix-ocsp                 |
   |       | OID:             1.3.6.1.5.5.7.48.1                       |
   |       | DER:             06 08 2B 06 01 05 05 07 30 01            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            CA Issuers                               |
   |       | Identifiers:     id-ad-caIssuers, caIssuers               |
   |       | OID:             1.3.6.1.5.5.7.48.2                       |
   |       | DER:             06 08 2B 06 01 05 05 07 30 02            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Time Stamping                            |
   |       | Identifiers:     id-ad-timeStamping, timeStamping         |
   |       | OID:             1.3.6.1.5.5.7.48.3                       |
   |       | DER:             06 08 2B 06 01 05 05 07 30 03            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            CA Repository                            |
   |       | Identifiers:     id-ad-caRepository                       |
   |       | OID:             1.3.6.1.5.5.7.48.5                       |
   |       | DER:             06 08 2B 06 01 05 05 07 30 05            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            RPKI Manifest                            |
   |       | Identifiers:     id-ad-rpkiManifest                       |
   |       | OID:             1.3.6.1.5.5.7.48.10                      |
   |       | DER:             06 08 2B 06 01 05 05 07 30 0A            |
   |       | Comments:        RFC 6487                                 |
   +-------+-----------------------------------------------------------+
   |    11 | Name:            Signed Object                            |
   |       | Identifiers:     id-ad-signedObject                       |
   |       | OID:             1.3.6.1.5.5.7.48.11                      |
   |       | DER:             06 08 2B 06 01 05 05 07 30 0B            |
   |       | Comments:        RFC 6487                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:            RPKI Notify                              |
   |       | Identifiers:     id-ad-rpkiNotify                         |
   |       | OID:             1.3.6.1.5.5.7.48.13                      |
   |       | DER:             06 08 2B 06 01 05 05 07 30 0D            |
   |       | Comments:        RFC 8182                                 |
   +-------+-----------------------------------------------------------+

                    Figure 12: C509 Information Accesses

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9.8.  C509 Extended Key Usages Registry

   IANA has created a new registry titled "C509 Extended Key Usages
   Registry" under the new heading "CBOR Encoded X.509 (C509)
   Parameters".  The columns of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  For values in the
   interval [-24, 23] the registration procedure is "IETF Review" and
   "Expert Review".  Values ≥ 32768 are reserved for Private Use. For
   all other values the registration procedure is "Expert Review".  The
   initial contents of the registry are:

    +-------+---------------------------------------------------------+
    | Value | Extended Key Usage                                      |
    +=======+=========================================================+
    |     0 | Name:            Any Extended Key Usage                 |
    |       | Identifiers:     anyExtendedKeyUsage                    |
    |       | OID:             2.5.29.37.0                            |
    |       | DER:             06 04 55 1D 25 00                      |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     1 | Name:            TLS Server authentication              |
    |       | Identifiers:     id-kp-serverAuth                       |
    |       | OID:             1.3.6.1.5.5.7.3.1                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 01          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     2 | Name:            TLS Client Authentication              |
    |       | Identifiers:     id-kp-clientAuth                       |
    |       | OID:             1.3.6.1.5.5.7.3.2                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 02          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     3 | Name:            Code Signing                           |
    |       | Identifiers:     id-kp-codeSigning                      |
    |       | OID:             1.3.6.1.5.5.7.3.3                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 03          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     4 | Name:            Email protection (S/MIME)              |
    |       | Identifiers:     id-kp-emailProtection                  |
    |       | OID:             1.3.6.1.5.5.7.3.4                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 04          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     8 | Name:            Time Stamping                          |
    |       | Identifiers:     id-kp-timeStamping, timestamping       |
    |       | OID:             1.3.6.1.5.5.7.3.8                      |

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    |       | DER:             06 08 2B 06 01 05 05 07 03 08          |
    |       | Comments:                                               |
    +-------+---------------------------------------------------------+
    |     9 | Name:            OCSP Signing                           |
    |       | Identifiers:     id-kp-OCSPSigning                      |
    |       | OID:             1.3.6.1.5.5.7.3.9                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 09          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |    10 | Name:            Kerberos PKINIT Client Auth            |
    |       | Identifiers:     id-pkinit-KPClientAuth                 |
    |       | OID:             1.3.6.1.5.2.3.4                        |
    |       | DER:             06 07 2B 06 01 05 02 03 04             |
    |       | Comments:        RFC 4556                               |
    +-------+---------------------------------------------------------+
    |    11 | Name:            Kerberos PKINIT KDC                    |
    |       | Identifiers:     id-pkinit-KPKdc                        |
    |       | OID:             1.3.6.1.5.2.3.5                        |
    |       | DER:             06 07 2B 06 01 05 02 03 05             |
    |       | Comments:        RFC 4556                               |
    +-------+---------------------------------------------------------+
    |    12 | Name:            SSH Client                             |
    |       | Identifiers:     id-kp-secureShellClient                |
    |       | OID:             1.3.6.1.5.5.7.3.21                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 15          |
    |       | Comments:        RFC 6187                               |
    +-------+---------------------------------------------------------+
    |    13 | Name:            SSH Server                             |
    |       | Identifiers:     id-kp-secureShellServer                |
    |       | OID:             1.3.6.1.5.5.7.3.22                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 16          |
    |       | Comments:        RFC 6187                               |
    +-------+---------------------------------------------------------+
    |    14 | Name:            Bundle Security                        |
    |       | Identifiers:     id-kp-bundleSecurity                   |
    |       | OID:             1.3.6.1.5.5.7.3.35                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 23          |
    |       | Comments:        RFC 9174                               |
    +-------+---------------------------------------------------------+
    |    15 | Name:            CMC Certification Authority            |
    |       | Identifiers:     id-kp-cmcCA                            |
    |       | OID:             1.3.6.1.5.5.7.3.27                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 1B          |
    |       | Comments:        RFC 6402                               |
    +-------+---------------------------------------------------------+
    |    16 | Name:            CMC Registration Authority             |
    |       | Identifiers:     id-kp-cmcRA                            |
    |       | OID:             1.3.6.1.5.5.7.3.28                     |

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    |       | DER:             06 08 2B 06 01 05 05 07 03 1C          |
    |       | Comments:        RFC 6402                               |
    +-------+---------------------------------------------------------+
    |    17 | Name:            CMC Archive Server                     |
    |       | Identifiers:     id-kp-cmcArchive                       |
    |       | OID:             1.3.6.1.5.5.7.3.29                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 1D          |
    |       | Comments:        RFC 6402                               |
    +-------+---------------------------------------------------------+
    |    18 | Name:            CMC Key Generation Authority           |
    |       | Identifiers:     id-kp-cmKGA                            |
    |       | OID:             1.3.6.1.5.5.7.3.32                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 20          |
    |       | Comments:        RFC 9480                               |
    +-------+---------------------------------------------------------+

                    Figure 13: C509 Extended Key Usages

9.9.  C509 General Names Registry

   IANA has created a new registry titled "C509 General Names Registry"
   under the new heading "CBOR Encoded X.509 (C509) Parameters".  The
   columns of the registry are Value, General Name, and Reference, where
   Value is an integer, and the other columns are text strings.  For
   values in the interval [-24, 23] the registration procedure is "IETF
   Review" and "Expert Review".  For all other values the registration
   procedure is "Expert Review".  The initial contents of the registry
   are:

   +-------+-----------------------------------------------------------+
   | Value | General Names                                             |
   +=======+===========================================================+
   |    -3 | Name:            otherName with BundleEID                 |
   |       | Comments:        id-on-bundleEID                          |
   |       |                  (1.3.6.1.5.5.7.8.11)                     |
   |       |                  06 08 2B 06 01 05 05 07 08 0B            |
   |       | Value:           eid-structure from RFC 9171              |
   +-------+-----------------------------------------------------------+
   |    -2 | Name:            otherName with SmtpUTF8Mailbox           |
   |       | Comments:        id-on-SmtpUTF8Mailbox                    |
   |       |                  (1.3.6.1.5.5.7.8.9)                      |
   |       |                  06 08 2B 06 01 05 05 07 08 09            |
   |       | Value:           text                                     |
   +-------+-----------------------------------------------------------+
   |    -1 | Name:            otherName with hardwareModuleName        |
   |       | Comments:        id-on-hardwareModuleName                 |
   |       |                  (1.3.6.1.5.5.7.8.4)                      |
   |       |                  06 08 2B 06 01 05 05 07 08 04            |

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   |       | Value:           [ ~oid, bytes ]                          |
   +-------+-----------------------------------------------------------+
   |     0 | Name:            otherName                                |
   |       | Comments:                                                 |
   |       | Value:           [ ~oid, bytes ]                          |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            rfc822Name                               |
   |       | Comments:                                                 |
   |       | Value:           text                                     |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            dNSName                                  |
   |       | Comments:                                                 |
   |       | Value:           text                                     |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            directoryName                            |
   |       | Comments:                                                 |
   |       | Value:           Name                                     |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            uniformResourceIdentifier                |
   |       | Comments:                                                 |
   |       | Value:           text                                     |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            iPAddress                                |
   |       | Comments:                                                 |
   |       | Value:           bytes                                    |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            registeredID                             |
   |       | Comments:                                                 |
   |       | Value:           ~oid                                     |
   +-------+-----------------------------------------------------------+

                       Figure 14: C509 General Names

9.10.  C509 Signature Algorithms Registry

   IANA has created a new registry titled "C509 Signature Algorithms"
   under the new heading "CBOR Encoded X.509 (C509) Parameters".  The
   registry includes both signature algorithms and non-signature proof-
   of-possession algorithms.  The columns of the registry are Value,
   Name, Identifiers, OID, Parameters, DER, Comments, and Reference,
   where Value is an integer, and the other columns are text strings.
   For values in the interval [-24, 23] the registration procedure is
   "IETF Review" and "Expert Review".  For all other values the
   registration procedure is "Expert Review".  The initial contents of
   the registry are:

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   +-------+-----------------------------------------------------------+
   | Value | X.509 Signature Algorithms                                |
   +=======+===========================================================+
   |  -256 | Name:        RSASSA-PKCS1-v1_5 with SHA-1                 |
   |       | Identifiers: sha1-with-rsa-signature,                     |
   |       |              sha1WithRSAEncryption,                       |
   |       |              sha-1WithRSAEncryption                       |
   |       | OID:         1.2.840.113549.1.1.5                         |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0D 06 09 2A 86 48 86 F7 0D 01 01 05 05 00 |
   |       | Comments:    Don't use                                    |
   +-------+-----------------------------------------------------------+
   |  -255 | Name:        ECDSA with SHA-1                             |
   |       | Identifiers: ecdsa-with-SHA1                              |
   |       | OID:         1.2.840.10045.4.1                            |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 09 06 07 2A 86 48 CE 3D 04 01             |
   |       | Comments:    Don't use. Compressed signature value        |
   +-------+-----------------------------------------------------------+
   |     0 | Name:        ECDSA with SHA-256                           |
   |       | Identifiers: ecdsa-with-SHA256                            |
   |       | OID:         1.2.840.10045.4.3.2                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 86 48 CE 3D 04 03 02          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |     1 | Name:        ECDSA with SHA-384                           |
   |       | Identifiers: ecdsa-with-SHA384                            |
   |       | OID:         1.2.840.10045.4.3.3                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 86 48 CE 3D 04 03 03          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |     2 | Name:        ECDSA with SHA-512                           |
   |       | Identifiers: ecdsa-with-SHA512                            |
   |       | OID:         1.2.840.10045.4.3.4                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 86 48 CE 3D 04 03 04          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |     3 | Name:        ECDSA with SHAKE128                          |
   |       | Identifiers: id-ecdsa-with-shake128                       |
   |       | OID:         1.3.6.1.5.5.7.6.32                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 20          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |     4 | Name:        ECDSA with SHAKE256                          |

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   |       | Identifiers: id-ecdsa-with-shake256                       |
   |       | OID:         1.3.6.1.5.5.7.6.33                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 21          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |    12 | Name:        Ed25519                                      |
   |       | Identifiers: id-Ed25519, id-EdDSA25519                    |
   |       | OID:         1.3.101.112                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 70                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:        Ed448                                        |
   |       | Identifiers: id-Ed448, id-EdDSA448                        |
   |       | OID:         1.3.101.113                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 71                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14 | Name:        SHA-256 with HMAC-SHA256                     |
   |       | Identifiers: sa-ecdhPop-sha256-hmac-sha256                |
   |       | OID:         1.3.6.1.5.5.7.6.26                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1A          |
   |       | Comments:    Proof-of-possession algorithm, indexed with  |
   |       |              KDF and MAC, see RFC 6955. Requires          |
   |       |              recipient public static Diffie-Hellman key.  |
   +-------+-----------------------------------------------------------+
   |    15 | Name:        SHA-384 with HMAC-SHA384                     |
   |       | Identifiers: sa-ecdhPop-sha384-hmac-sha384                |
   |       | OID:         1.3.6.1.5.5.7.6.27                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1B          |
   |       | Comments:    Proof-of-possession algorithm, indexed with  |
   |       |              KDF and MAC, see RFC 6955. Requires          |
   |       |              recipient public static Diffie-Hellman key.  |
   +-------+-----------------------------------------------------------+
   |    16 | Name:        SHA-512 with HMAC-SHA512                     |
   |       | Identifiers: sa-ecdhPop-sha512-hmac-sha512                |
   |       | OID:         1.3.6.1.5.5.7.6.28                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1C          |
   |       | Comments:    Proof-of-possession algorithm, indexed with  |
   |       |              KDF and MAC, see RFC 6955. Requires          |
   |       |              recipient public static Diffie-Hellman key.  |
   +-------+-----------------------------------------------------------+
   |    23 | Name:        RSASSA-PKCS1-v1_5 with SHA-256               |

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   |       | Identifiers: sha256WithRSAEncryption                      |
   |       | OID:         1.2.840.113549.1.1.11                        |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0B 06 09 2A 86 48 86 F7 0D 01 01 0B 05 00 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    24 | Name:        RSASSA-PKCS1-v1_5 with SHA-384               |
   |       | Identifiers: sha384WithRSAEncryption                      |
   |       | OID:         1.2.840.113549.1.1.12                        |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0B 06 09 2A 86 48 86 F7 0D 01 01 0C 05 00 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    25 | Name:        RSASSA-PKCS1-v1_5 with SHA-512               |
   |       | Identifiers: sha512WithRSAEncryption                      |
   |       | OID:         1.2.840.113549.1.1.13                        |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0B 06 09 2A 86 48 86 F7 0D 01 01 0D 05 00 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    26 | Name:        RSASSA-PSS with SHA-256                      |
   |       | Identifiers: rsassa-pss, id-RSASSA-PSS                    |
   |       | OID:         1.2.840.113549.1.1.10                        |
   |       | Parameters:  SHA-256, MGF-1 with SHA-256, saltLength = 32 |
   |       | DER:         30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 |
   |       |              A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 01 |
   |       |              05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 |
   |       |              01 08 30 0D 06 09 60 86 48 01 65 03 04 02 01 |
   |       |              05 00 a2 03 02 01 20                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    27 | Name:        RSASSA-PSS with SHA-384                      |
   |       | Identifiers: rsassa-pss, id-RSASSA-PSS                    |
   |       | OID:         1.2.840.113549.1.1.10                        |
   |       | Parameters:  SHA-384, MGF-1 with SHA-384, saltLength = 48 |
   |       | DER:         30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 |
   |       |              A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 02 |
   |       |              05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 |
   |       |              01 08 30 0D 06 09 60 86 48 01 65 03 04 02 02 |
   |       |              05 00 A2 03 02 01 30                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    28 | Name:        RSASSA-PSS with SHA-512                      |
   |       | Identifiers: rsassa-pss, id-RSASSA-PSS                    |
   |       | OID:         1.2.840.113549.1.1.10                        |
   |       | Parameters:  SHA-512, MGF-1 with SHA-512, saltLength = 64 |
   |       | DER:         30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 |
   |       |              A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 03 |

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   |       |              05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 |
   |       |              01 08 30 0D 06 09 60 86 48 01 65 03 04 02 03 |
   |       |              05 00 A2 03 02 01 40                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    29 | Name:        RSASSA-PSS with SHAKE128                     |
   |       | Identifiers: id-RSASSA-PSS-SHAKE128                       |
   |       | OID:         1.3.6.1.5.5.7.6.30                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1E          |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    30 | Name:        RSASSA-PSS with SHAKE256                     |
   |       | Identifiers: id-RSASSA-PSS-SHAKE256                       |
   |       | OID:         1.3.6.1.5.5.7.6.31                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1F          |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    42 | Name:        HSS / LMS                                    |
   |       | Identifiers: id-alg-hss-lms-hashsig, id-alg-mts-hashsig   |
   |       | OID:         1.2.840.113549.1.9.16.3.17                   |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0D 06 0B 2A 86 48 86 F7 0D 01 09 10 03 11 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    43 | Name:        XMSS                                         |
   |       | Identifiers: id_alg_xmss                                  |
   |       | OID:         0.4.0.127.0.15.1.1.13.0                      |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0B 06 09 04 00 7F 00 0F 01 01 0D 00       |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    44 | Name:        XMSS^MT                                      |
   |       | Identifiers: id_alg_xmssmt                                |
   |       | OID:         0.4.0.127.0.15.1.1.14.0                      |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0B 06 09 04 00 7F 00 0F 01 01 0E 00       |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    45 | Name:        SM2 with SM3                                 |
   |       | Identifiers: sm2-with-sm3                                 |
   |       | OID:         1.2.156.10197.1.501                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 81 1C CF 55 01 83 75          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+

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                    Figure 15: C509 Signature Algorithms

9.11.  C509 Public Key Algorithms Registry

   IANA has created a new registry titled "C509 Public Key Algorithms"
   under the new heading "CBOR Encoded X.509 (C509) Parameters".  The
   columns of the registry are Value, Name, Identifiers, OID,
   Parameters, DER, Comments, and Reference, where Value is an integer,
   and the other columns are text strings.  For values in the interval
   [-24, 23] the registration procedure is "IETF Review" and "Expert
   Review".  For all other values the registration procedure is "Expert
   Review".  T The initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | X.509 Public Key Algorithms                               |
   +=======+===========================================================+
   |     0 | Name:        RSA                                          |
   |       | Identifiers: rsaEncryption                                |
   |       | OID:         1.2.840.113549.1.1.1                         |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0d 06 09 2a 86 48 86 f7 0d 01 01 01 05 00 |
   |       | Comments:    Compressed subjectPublicKey                  |
   +-------+-----------------------------------------------------------+
   |     1 | Name:        EC Public Key (Weierstraß) with secp256r1    |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = secp256r1 (1.2.840.10045.3.1.7) |
   |       | DER:         30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86 |
   |       |              48 CE 3D 03 01 07                            |
   |       | Comments:    Point compressed subjectPublicKey            |
   |       |              Also known as P-256, ansip256r1, prime256v1  |
   +-------+-----------------------------------------------------------+
   |     2 | Name:        EC Public Key (Weierstraß) with secp384r1    |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = secp384r1 (1.3.132.0.34)        |
   |       | DER:         30 10 06 07 2A 86 48 CE 3D 02 01 06 05 2B 81 |
   |       |              04 00 22                                     |
   |       | Comments:    Point compressed subjectPublicKey            |
   |       |              Also known as P-384, ansip384r1              |
   +-------+-----------------------------------------------------------+
   |     3 | Name:        EC Public Key (Weierstraß) with secp521r1    |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = secp521r1 (1.3.132.0.35)        |
   |       | DER:         30 10 06 07 2A 86 48 CE 3D 02 01 06 05 2B 81 |
   |       |              04 00 23                                     |
   |       | Comments:    Point compressed subjectPublicKey            |

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   |       |              Also known as P-521, ansip521r1              |
   +-------+-----------------------------------------------------------+
   |     8 | Name:        X25519 (Montgomery)                          |
   |       | Identifiers: id-X25519                                    |
   |       | OID:         1.3.101.110                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 6E                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     9 | Name:        X448 (Montgomery)                            |
   |       | Identifiers: id-X448                                      |
   |       | OID:         1.3.101.111                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 6F                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    10 | Name:        Ed25519 (Twisted Edwards)                    |
   |       | Identifiers: id-Ed25519, id-EdDSA25519                    |
   |       | OID:         1.3.101.112                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 70                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    11 | Name:        Ed448 (Edwards)                              |
   |       | Identifiers: id-Ed448, id-EdDSA448                        |
   |       | OID:         1.3.101.113                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 71                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    16 | Name:        HSS / LMS                                    |
   |       | Identifiers: id-alg-hss-lms-hashsig, id-alg-mts-hashsig   |
   |       | OID:         1.2.840.113549.1.9.16.3.17                   |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0D 06 0B 2A 86 48 86 F7 0D 01 09 10 03 11 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    17 | Name:        XMSS                                         |
   |       | Identifiers: id_alg_xmss                                  |
   |       | OID:         0.4.0.127.0.15.1.1.13.0                      |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0B 06 09 04 00 7F 00 0F 01 01 0D 00       |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    18 | Name:        XMSS^MT                                      |
   |       | Identifiers: id_alg_xmssmt                                |
   |       | OID:         0.4.0.127.0.15.1.1.14.0                      |
   |       | Parameters:  Absent                                       |

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   |       | DER:         30 0B 06 09 04 00 7F 00 0F 01 01 0E 00       |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    24 | Name:        EC Public Key (Weierstraß) with              |
   |       |              brainpoolP256r1                              |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = brainpoolP256r1                 |
   |       |              (1.3.36.3.3.2.8.1.1.7)                       |
   |       | DER:         30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 |
   |       |              03 03 02 08 01 01 07                         |
   |       | Comments:    Point compressed subjectPublicKey            |
   +-------+-----------------------------------------------------------+
   |    25 | Name:        EC Public Key (Weierstraß) with              |
   |       |              brainpoolP384r1                              |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = brainpoolP384r1                 |
   |       |              (1.3.36.3.3.2.8.1.1.11)                      |
   |       | DER:         30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 |
   |       |              03 03 02 08 01 01 0B                         |
   |       | Comments:    Point compressed subjectPublicKey            |
   +-------+-----------------------------------------------------------+
   |    26 | Name:        EC Public Key (Weierstraß) with              |
   |       |              brainpoolP512r1                              |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = brainpoolP512r1                 |
   |       |              (1.3.36.3.3.2.8.1.1.13)                      |
   |       | DER:         30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 |
   |       |              03 03 02 08 01 01 0D                         |
   |       | Comments:    Point compressed subjectPublicKey            |
   +-------+-----------------------------------------------------------+
   |    27 | Name:        EC Public Key (Weierstraß) with              |
   |       |              FRP256v1                                     |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = FRP256v1                        |
   |       |              (1.2.250.1.223.101.256.1)                    |
   |       | DER:         30 15 06 07 2A 86 48 CE 3D 02 01 06 0A 2A 81 |
   |       |              7A 01 81 5F 65 82 00 01                      |
   |       | Comments:    Point compressed subjectPublicKey            |
   +-------+-----------------------------------------------------------+
   |    28 | Name:        EC Public Key (Weierstraß) with              |
   |       |              sm2p256v1                                    |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = sm2p256v1                       |

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   |       |              (1.2.156.10197.1.301)                        |
   |       | DER:         30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 81 |
   |       |              1C CF 55 01 82 2D                            |
   |       | Comments:    Point compressed subjectPublicKey            |
   +-------+-----------------------------------------------------------+

                   Figure 16: C509 Public Key Algorithms

9.11.1.  Suitability of different public key algorithms for use within
         IoT scenarios

   The public key algorithms registry Section 9.11 specify a number of
   algorithms, not all which are suitable for usage with constrained
   devices.  RSA requires large keys and large signature sizes compared
   to elliptic curve cryptography (ECC), which together with resource-
   efficient implementations of named elliptic curves (Montgomery,
   Edwards and Weierstraß curves), make them suitable candidates for IoT
   public key usage.  These curves are represented by ids 1–11 and 24–28
   in Section 9.11.

9.12.  COSE Header Parameters Registry

   IANA is requested to assign the entries in Table 1 to the "COSE
   Header Parameters" registry under the "CBOR Object Signing and
   Encryption (COSE)" heading with this document as reference.

9.13.  Media Type application/cose-c509-cert

   When the application/cose-c509-cert media type is used, the data is a
   COSE_C509 structure.  If the parameter "usage" is set to "chain",
   this sequence indicates a certificate chain.

   IANA has registered the following media type [RFC6838]:

   Type name: application

   Subtype name: cose-c509-cert

   Required parameters: N/A

   Optional parameters: usage

   *  Can be absent to provide no further information about the intended
      meaning of the order in the CBOR sequence of certificates.

   *  Can be set to "chain" to indicate that the sequence of data items
      is to be interpreted as a certificate chain.

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   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [[this document]].

   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and use C509 as a certificate type.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): TBD8

   *  File extension(s): .c509

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IESG

9.14.  Media Type application/cose-c509-pkcs10

   When the application/cose-c509-pkcs10 media type is used, the data is
   a C509CertificateRequest structure.

   IANA has registered the following media type [RFC6838]:

   Type name: application

   Subtype name: cose-c509-pkcs10

   Required parameters: N/A

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   Optional parameters: N/A

   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [[this document]].

   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and C509 Certificate Request.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): TBD9

   *  File extension(s): .c509

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IESG

9.15.  Media Type application/cose-c509-privkey

   When the application/cose-c509-privkey media type is used, the data
   is a C509PrivateKey structure.

   IANA has registered the following media type [RFC6838]:

   Type name: application

   Subtype name: cose-c509-privkey

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   Required parameters: N/A

   Optional parameters: usage

   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [[this document]].

   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and use C509 as a certificate type.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): TBD12

   *  File extension(s): .c509

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IESG

9.16.  Media Type application/cose-c509-pem

   When the application/cose-c509-pem media type is used, the data is a
   C509PEM structure.

   IANA has registered the following media type [RFC6838]:

   Type name: application

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   Subtype name: cose-c509-pem

   Required parameters: N/A

   Optional parameters: usage

   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [[this document]].

   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and use C509 as a certificate type.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): TBD13

   *  File extension(s): .c509

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IESG

9.17.  CoAP Content-Formats Registry

   IANA is requested to add the media types "application/cose-
   c509-cert", "application/cose-c509-pkcs10", "application/cose-
   c509-privkey" and "application/cose-c509-pem" to the "CoAP Content-
   Formats" registry under the registry group "Constrained RESTful
   Environments (CoRE) Parameters".

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+--------------------------------+----------+-------+-------------------+
| Media Type                     | Encoding | ID    | Reference         |
+================================+==========+=======+===================+
| application/cose-c509-cert     | -        |  TBD6 | [[this document]] |
| application/cose-c509-pkcs10   | -        |  TBD7 | [[this document]] |
| application/cose-c509-privkey  | -        | TBD10 | [[this document]] |
| application/cose-c509-pem      | -        | TBD11 | [[this document]] |
+--------------------------------+----------+-------+-------------------+

                  Figure 17: CoAP Content-Format IDs

9.18.  TLS Certificate Types Registry

   This document registers the following entry in the "TLS Certificate
   Types" registry under the "Transport Layer Security (TLS) Extensions"
   heading.  The new certificate type can be used with additional TLS
   certificate compression [RFC8879].  C509 is defined in the same way
   as as X.509, but uses a different value and instead of DER-encoded
   X.509 certificate, opaque cert_data<1..2^24-1> contains a the CBOR
   sequence ~C509Certificate (an unwrapped C509Certificate).

   Editor's Note: The TLS registrations should be discussed and approved
   by the TLS WG at a later stage.  The TLS WG might e.g. want a
   separate draft in the TLS WG.

   +-------+------------------+-------------+--------------------------+
   | Value | Name             | Recommended | Comment                  |
   +=======+==================+=============+==========================+
   |  TBD5 | C509 Certificate |           Y |                          |
   +-------+------------------+-------------+--------------------------+

9.19.  CBOR Tags Registry

   This document registers the following entries in the "CBOR Tags"
   registry under the "Concise Binary Object Representation (CBOR) Tags"
   heading.

   +------+------------------------------------------------------------+
   |  Tag | X.509 Public Key Algorithms                                |
   +======+============================================================+
   | TDB6 | Data Item: COSE_C509                                       |
   |      | Semantics: An ordered chain of C509 certificates           |
   |      | Reference: This document                                   |
   +------+------------------------------------------------------------+

10.  References

10.1.  Normative References

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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2985]  Nystrom, M. and B. Kaliski, "PKCS #9: Selected Object
              Classes and Attribute Types Version 2.0", RFC 2985,
              DOI 10.17487/RFC2985, November 2000,
              <https://www.rfc-editor.org/info/rfc2985>.

   [RFC2986]  Nystrom, M. and B. Kaliski, "PKCS #10: Certification
              Request Syntax Specification Version 1.7", RFC 2986,
              DOI 10.17487/RFC2986, November 2000,
              <https://www.rfc-editor.org/info/rfc2986>.

   [RFC3039]  Santesson, S., Polk, W., Barzin, P., and M. Nystrom,
              "Internet X.509 Public Key Infrastructure Qualified
              Certificates Profile", RFC 3039, DOI 10.17487/RFC3039,
              January 2001, <https://www.rfc-editor.org/info/rfc3039>.

   [RFC4108]  Housley, R., "Using Cryptographic Message Syntax (CMS) to
              Protect Firmware Packages", RFC 4108,
              DOI 10.17487/RFC4108, August 2005,
              <https://www.rfc-editor.org/info/rfc4108>.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
              <https://www.rfc-editor.org/info/rfc5280>.

   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,
              <https://www.rfc-editor.org/info/rfc6838>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8610]  Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
              Definition Language (CDDL): A Notational Convention to
              Express Concise Binary Object Representation (CBOR) and
              JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
              June 2019, <https://www.rfc-editor.org/info/rfc8610>.

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   [RFC8742]  Bormann, C., "Concise Binary Object Representation (CBOR)
              Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020,
              <https://www.rfc-editor.org/info/rfc8742>.

   [RFC8949]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/info/rfc8949>.

   [RFC9052]  Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Structures and Process", STD 96, RFC 9052,
              DOI 10.17487/RFC9052, August 2022,
              <https://www.rfc-editor.org/info/rfc9052>.

   [RFC9090]  Bormann, C., "Concise Binary Object Representation (CBOR)
              Tags for Object Identifiers", RFC 9090,
              DOI 10.17487/RFC9090, July 2021,
              <https://www.rfc-editor.org/info/rfc9090>.

   [RFC9277]  Richardson, M. and C. Bormann, "On Stable Storage for
              Items in Concise Binary Object Representation (CBOR)",
              RFC 9277, DOI 10.17487/RFC9277, August 2022,
              <https://www.rfc-editor.org/info/rfc9277>.

   [RFC9360]  Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Header Parameters for Carrying and Referencing X.509
              Certificates", RFC 9360, DOI 10.17487/RFC9360, February
              2023, <https://www.rfc-editor.org/info/rfc9360>.

   [SECG]     "Elliptic Curve Cryptography, Standards for Efficient
              Cryptography Group, ver. 2", 2009,
              <https://secg.org/sec1-v2.pdf>.

10.2.  Informative References

   [CAB-Code] CA/Browser Forum, "CA/Browser Forum, "Baseline
              Requirements for the Issuance and Management of Publicly-
              Trusted Code Signing Certificates Version 2.3"", May 2021,
              <https://cabforum.org/baseline-requirements-code-
              signing/>.

   [CAB-TLS]  CA/Browser Forum, "CA/Browser Forum, "Baseline
              Requirements for the Issuance and Management of Publicly-
              Trusted Certificates Version 1.7.6"", June 2021,
              <https://cabforum.org/baseline-requirements-documents/>.

   [CborMe]   Bormann, C., "CBOR Playground", May 2018,
              <https://cbor.me/>.

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   [GSMA-eUICC]
              GSMA, "GSMA eUICC PKI Certificate Policy Version 2.1",
              February 2021, <https://www.gsma.com/esim/wp-
              content/uploads/2021/02/SGP.14-v2.1.pdf>.

   [I-D.ietf-lake-edhoc]
              Selander, G., Mattsson, J. P., and F. Palombini,
              "Ephemeral Diffie-Hellman Over COSE (EDHOC)", Work in
              Progress, Internet-Draft, draft-ietf-lake-edhoc-23, 22
              January 2024, <https://datatracker.ietf.org/doc/html/
              draft-ietf-lake-edhoc-23>.

   [I-D.ietf-tls-ctls]
              Rescorla, E., Barnes, R., Tschofenig, H., and B. M.
              Schwartz, "Compact TLS 1.3", Work in Progress, Internet-
              Draft, draft-ietf-tls-ctls-10, 17 April 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-tls-
              ctls-10>.

   [I-D.ietf-uta-tls13-iot-profile]
              Tschofenig, H., Fossati, T., and M. Richardson, "TLS/DTLS
              1.3 Profiles for the Internet of Things", Work in
              Progress, Internet-Draft, draft-ietf-uta-tls13-iot-
              profile-09, 3 March 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-uta-
              tls13-iot-profile-09>.

   [IEEE-802.1AR]
              Institute of Electrical and Electronics Engineers, "IEEE
              Standard for Local and metropolitan area networks–Secure
              Device Identity", IEEE Standard 802.1AR-2018 , August
              2018,
              <https://standards.ieee.org/standard/802_1AR-2018.html>.

   [RFC6487]  Huston, G., Michaelson, G., and R. Loomans, "A Profile for
              X.509 PKIX Resource Certificates", RFC 6487,
              DOI 10.17487/RFC6487, February 2012,
              <https://www.rfc-editor.org/info/rfc6487>.

   [RFC6955]  Schaad, J. and H. Prafullchandra, "Diffie-Hellman Proof-
              of-Possession Algorithms", RFC 6955, DOI 10.17487/RFC6955,
              May 2013, <https://www.rfc-editor.org/info/rfc6955>.

   [RFC7228]  Bormann, C., Ersue, M., and A. Keranen, "Terminology for
              Constrained-Node Networks", RFC 7228,
              DOI 10.17487/RFC7228, May 2014,
              <https://www.rfc-editor.org/info/rfc7228>.

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   [RFC7468]  Josefsson, S. and S. Leonard, "Textual Encodings of PKIX,
              PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468,
              April 2015, <https://www.rfc-editor.org/info/rfc7468>.

   [RFC7925]  Tschofenig, H., Ed. and T. Fossati, "Transport Layer
              Security (TLS) / Datagram Transport Layer Security (DTLS)
              Profiles for the Internet of Things", RFC 7925,
              DOI 10.17487/RFC7925, July 2016,
              <https://www.rfc-editor.org/info/rfc7925>.

   [RFC7932]  Alakuijala, J. and Z. Szabadka, "Brotli Compressed Data
              Format", RFC 7932, DOI 10.17487/RFC7932, July 2016,
              <https://www.rfc-editor.org/info/rfc7932>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC8603]  Jenkins, M. and L. Zieglar, "Commercial National Security
              Algorithm (CNSA) Suite Certificate and Certificate
              Revocation List (CRL) Profile", RFC 8603,
              DOI 10.17487/RFC8603, May 2019,
              <https://www.rfc-editor.org/info/rfc8603>.

   [RFC8879]  Ghedini, A. and V. Vasiliev, "TLS Certificate
              Compression", RFC 8879, DOI 10.17487/RFC8879, December
              2020, <https://www.rfc-editor.org/info/rfc8879>.

   [RFC9000]  Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
              Multiplexed and Secure Transport", RFC 9000,
              DOI 10.17487/RFC9000, May 2021,
              <https://www.rfc-editor.org/info/rfc9000>.

   [RFC9147]  Rescorla, E., Tschofenig, H., and N. Modadugu, "The
              Datagram Transport Layer Security (DTLS) Protocol Version
              1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,
              <https://www.rfc-editor.org/info/rfc9147>.

   [RFC9148]  van der Stok, P., Kampanakis, P., Richardson, M., and S.
              Raza, "EST-coaps: Enrollment over Secure Transport with
              the Secure Constrained Application Protocol", RFC 9148,
              DOI 10.17487/RFC9148, April 2022,
              <https://www.rfc-editor.org/info/rfc9148>.

   [RFC9190]  Preuß Mattsson, J. and M. Sethi, "EAP-TLS 1.3: Using the
              Extensible Authentication Protocol with TLS 1.3",
              RFC 9190, DOI 10.17487/RFC9190, February 2022,
              <https://www.rfc-editor.org/info/rfc9190>.

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   [RFC9191]  Sethi, M., Preuß Mattsson, J., and S. Turner, "Handling
              Large Certificates and Long Certificate Chains in TLS-
              Based EAP Methods", RFC 9191, DOI 10.17487/RFC9191,
              February 2022, <https://www.rfc-editor.org/info/rfc9191>.

   [SP-800-56A]
              Barker, E., Chen, L., Roginsky, A., Vassilev, A., and R.
              Davis, "Recommendation for Pair-Wise Key-Establishment
              Schemes Using Discrete Logarithm Cryptography",
              NIST Special Publication 800-56A Revision 3, April 2018,
              <https://doi.org/10.6028/NIST.SP.800-56Ar3>.

   [X.509-IoT]
              Forsby, F., Furuhed, M., Papadimitratos, P., and S. Raza,
              "Lightweight X.509 Digital Certificates for the Internet
              of Things.", Springer, Cham. Lecture Notes of the
              Institute for Computer Sciences, Social Informatics and
              Telecommunications Engineering, vol 242., July 2018,
              <https://doi.org/10.1007/978-3-319-93797-7_14>.

Appendix A.  Example C509 Certificates

A.1.  Example RFC 7925 profiled X.509 Certificate

   Example of [RFC7925] profiled X.509 certificate parsed with OpenSSL.

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   Certificate:
       Data:
           Version: 3 (0x2)
           Serial Number: 128269 (0x1f50d)
           Signature Algorithm: ecdsa-with-SHA256
           Issuer: CN=RFC test CA
           Validity
               Not Before: Jan  1 00:00:00 2023 GMT
               Not After : Jan  1 00:00:00 2026 GMT
           Subject: CN=01-23-45-FF-FE-67-89-AB
           Subject Public Key Info:
               Public Key Algorithm: id-ecPublicKey
                   Public-Key: (256 bit)
                   pub:
                       04:b1:21:6a:b9:6e:5b:3b:33:40:f5:bd:f0:2e:69:
                       3f:16:21:3a:04:52:5e:d4:44:50:b1:01:9c:2d:fd:
                       38:38:ab:ac:4e:14:d8:6c:09:83:ed:5e:9e:ef:24:
                       48:c6:86:1c:c4:06:54:71:77:e6:02:60:30:d0:51:
                       f7:79:2a:c2:06
                   ASN1 OID: prime256v1
                   NIST CURVE: P-256
           X509v3 extensions:
               X509v3 Key Usage:
                   Digital Signature
       Signature Algorithm: ecdsa-with-SHA256
           30:46:02:21:00:d4:32:0b:1d:68:49:e3:09:21:9d:30:03:7e:
           13:81:66:f2:50:82:47:dd:da:e7:6c:ce:ea:55:05:3c:10:8e:
           90:02:21:00:d5:51:f6:d6:01:06:f1:ab:b4:84:cf:be:62:56:
           c1:78:e4:ac:33:14:ea:19:19:1e:8b:60:7d:a5:ae:3b:da:16

   The DER encoding of the above certificate is 316 bytes.

   30 82 01 38 30 81 de a0 03 02 01 02 02 03 01 f5 0d 30 0a 06 08 2a 86
   48 ce 3d 04 03 02 30 16 31 14 30 12 06 03 55 04 03 0c 0b 52 46 43 20
   74 65 73 74 20 43 41 30 1e 17 0d 32 33 30 31 30 31 30 30 30 30 30 30
   5a 17 0d 32 36 30 31 30 31 30 30 30 30 30 30 5a 30 22 31 20 30 1e 06
   03 55 04 03 0c 17 30 31 2d 32 33 2d 34 35 2d 46 46 2d 46 45 2d 36 37
   2d 38 39 2d 41 42 30 59 30 13 06 07 2a 86 48 ce 3d 02 01 06 08 2a 86
   48 ce 3d 03 01 07 03 42 00 04 b1 21 6a b9 6e 5b 3b 33 40 f5 bd f0 2e
   69 3f 16 21 3a 04 52 5e d4 44 50 b1 01 9c 2d fd 38 38 ab ac 4e 14 d8
   6c 09 83 ed 5e 9e ef 24 48 c6 86 1c c4 06 54 71 77 e6 02 60 30 d0 51
   f7 79 2a c2 06 a3 0f 30 0d 30 0b 06 03 55 1d 0f 04 04 03 02 07 80 30
   0a 06 08 2a 86 48 ce 3d 04 03 02 03 49 00 30 46 02 21 00 d4 32 0b 1d
   68 49 e3 09 21 9d 30 03 7e 13 81 66 f2 50 82 47 dd da e7 6c ce ea 55
   05 3c 10 8e 90 02 21 00 d5 51 f6 d6 01 06 f1 ab b4 84 cf be 62 56 c1
   78 e4 ac 33 14 ea 19 19 1e 8b 60 7d a5 ae 3b da 16

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A.1.1.  Example C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the same X.509 certificate is
   shown below in CBOR diagnostic format.

   /This defines a CBOR Sequence (RFC 8742):/

     3,                   / version and certificate type /
     h'01f50d',           / serialNumber /
     0,                   / signatureAlgorithm /
     "RFC test CA",       / issuer /
     1672531200,          / notBefore /
     1767225600,          / notAfter /
     h'010123456789AB',   / subject, EUI-64 /
     1,                   / subjectPublicKeyAlgorithm /
     h'FEB1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450
       B1019C2DFD3838AB',
     1,                   / single extension:
                            non-critical keyUsage
                            digitalSignature /
     h'D4320B1D6849E309219D30037E138166F2508247DDDAE76CCE
       EA55053C108E90D551F6D60106F1ABB484CFBE6256C178E4AC
       3314EA19191E8B607DA5AE3BDA16'

   The size of the CBOR encoding (CBOR sequence) is 139 bytes.  The
   point compressed public key is represented as described in
   Section 3.2.1.

   03
   43 01 F5 0D
   00
   6B 52 46 43 20 74 65 73 74 20 43 41
   1A 63 B0 CD 00
   1A 69 55 B9 00
   47 01 01 23 45 67 89 AB
   01
   58 21 FE B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
   5E D4 44 50 B1 01 9C 2D FD 38 38 AB
   01
   58 40 D4 32 0B 1D 68 49 E3 09 21 9D 30 03 7E 13 81 66 F2 50 82 47 DD
   DA E7 6C CE EA 55 05 3C 10 8E 90 D5 51 F6 D6 01 06 F1 AB B4 84 CF BE
   62 56 C1 78 E4 AC 33 14 EA 19 19 1E 8B 60 7D A5 AE 3B DA 16

A.1.2.  Example: Natively Signed C509 Certificate

   The corresponding natively signed C509 certificate in CBOR diagnostic
   format is identical, except for c509CertificateType, encoding of
   point compression (see Section 3.2.1), and signatureValue.

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   /This defines a CBOR Sequence (RFC 8742):/

     2,
     h'01f50d',
     0,
     "RFC test CA",
     1672531200,
     1767225600,
     h'010123456789AB',
     1,
     h'02B1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450
       B1019C2DFD3838AB',
     1,
     h'357B3D83F4ECD1B4E1D225A85C6BE2EADA3134375E72E5B6E2
       C311FC9F3DD5962585ABF644D68415194C245A579E134A7CA5
       313B90AEAFCAA7AF0DE440302146'

   The size of the CBOR encoding (CBOR sequence) is 139 bytes.

   02
   43 01 F5 0D
   00
   6B 52 46 43 20 74 65 73 74 20 43 41
   1A 63 B0 CD 00
   1A 69 55 B9 00
   47 01 01 23 45 67 89 AB
   01
   58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
   5E D4 44 50 B1 01 9C 2D FD 38 38 AB
   01
   58 40 35 7B 3D 83 F4 EC D1 B4 E1 D2 25 A8 5C 6B E2 EA DA 31 34 37 5E
   72 E5 B6 E2 C3 11 FC 9F 3D D5 96 25 85 AB F6 44 D6 84 15 19 4C 24 5A
   57 9E 13 4A 7C A5 31 3B 90 AE AF CA A7 AF 0D E4 40 30 21 46

A.1.3.  C509 for Diffie-Hellman keys

   The two previous examples illustrate the common key usage
   digitalSignature.  A C509 certificate for a public Diffie-Hellman key
   would instead have key usage keyAgreement encoded according to
   Section 3.3 (in this case of single extension encoded as integer 16
   instead of 1 for digital signature) but otherwise identical in
   format.  Note that Section 5.6.3.2 of [SP-800-56A] allows a key
   agreement key pair to be used to sign a certificate request.

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A.1.4.  Example: Additional Keys for the Example Certificates

   Below are the issuer key pair and the subject private key belonging
   to the above example certificates.  The private keys are encoded as
   in COSE [RFC9052].  These issuer key pair can be used to sign or
   verify the example certificates and the subject private key allows
   the example certificates to be used in test vectors for other
   protocols like EDHOC.

   issuerPublicKeyAlgorithm :
   1 (EC Public Key (Weierstraß) with secp256r1)

   issuerPublicKey :
   h'02AE4CDB01F614DEFC7121285FDC7F5C6D1D42C95647F061BA0080DF678867845E'

   issuerPrivateKey :
   h'DC66B3415456D649429B53223DF7532B942D6B0E0842C30BCA4C0ACF91547BB2'

   subjectPrivateKey :
   h'D718111F3F9BD91B92FF6877F386BDBFCEA7154268FD7F2FB56EE17D99EA16D4'

A.2.  Example IEEE 802.1AR profiled X.509 Certificate

   An example of an IEEE 802.1AR profiled X.509 certificate (Secure
   Device Identifier, DevID) is provided in Appendix C.2 of [RFC9148].
   The certificate is shown below including details of the
   hardwareModuleName type of otherName in subjectAltName, see
   Section 3.3.

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Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 9112578475118446130 (0x7e7661d7b54e4632)
        Signature Algorithm: ecdsa-with-SHA256
        Issuer: C=US, ST=CA, O=Example Inc, OU=certification, CN=802.1AR CA
        Validity
            Not Before: Jan 31 11:29:16 2019 GMT
            Not After : Dec 31 23:59:59 9999 GMT
        Subject: C=US, ST=CA, L=LA, O=example Inc, OU=IoT/serialNumber=Wt1234
        Subject Public Key Info:
            Public Key Algorithm: id-ecPublicKey
                Public-Key: (256 bit)
                pub:
                    04:c8:b4:21:f1:1c:25:e4:7e:3a:c5:71:23:bf:2d:
                    9f:dc:49:4f:02:8b:c3:51:cc:80:c0:3f:15:0b:f5:
                    0c:ff:95:8d:75:41:9d:81:a6:a2:45:df:fa:e7:90:
                    be:95:cf:75:f6:02:f9:15:26:18:f8:16:a2:b2:3b:
                    56:38:e5:9f:d9
                ASN1 OID: prime256v1
                NIST CURVE: P-256
        X509v3 extensions:
            X509v3 Basic Constraints:
                CA:FALSE
            X509v3 Subject Key Identifier:
                96:60:0D:87:16:BF:7F:D0:E7:52:D0:AC:76:07:77:AD:66:5D:02:A0
            X509v3 Authority Key Identifier:
                68:D1:65:51:F9:51:BF:C8:2A:43:1D:0D:9F:08:BC:2D:20:5B:11:60
            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Subject Alternative Name:
                otherName:
                    type-id: 1.3.6.1.5.5.7.8.4 (id-on-hardwareModuleName)
                    value:
                        hwType: 1.3.6.1.4.1.6175.10.1
                        hwSerialNum: 01:02:03:04
    Signature Algorithm: ecdsa-with-SHA256
    Signature Value:
        30:46:02:21:00:c0:d8:19:96:d2:50:7d:69:3f:3c:48:ea:a5:
        ee:94:91:bd:a6:db:21:40:99:d9:81:17:c6:3b:36:13:74:cd:
        86:02:21:00:a7:74:98:9f:4c:32:1a:5c:f2:5d:83:2a:4d:33:
        6a:08:ad:67:df:20:f1:50:64:21:18:8a:0a:de:6d:34:92:36

   The DER encoding of the certificate is 577 bytes:

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   30 82 02 3D 30 82 01 E2 A0 03 02 01 02 02 08 7E 76 61 D7 B5 4E 46 32
   30 0A 06 08 2A 86 48 CE 3D 04 03 02 30 5D 31 0B 30 09 06 03 55 04 06
   13 02 55 53 31 0B 30 09 06 03 55 04 08 0C 02 43 41 31 14 30 12 06 03
   55 04 0A 0C 0B 45 78 61 6D 70 6C 65 20 49 6E 63 31 16 30 14 06 03 55
   04 0B 0C 0D 63 65 72 74 69 66 69 63 61 74 69 6F 6E 31 13 30 11 06 03
   55 04 03 0C 0A 38 30 32 2E 31 41 52 20 43 41 30 20 17 0D 31 39 30 31
   33 31 31 31 32 39 31 36 5A 18 0F 39 39 39 39 31 32 33 31 32 33 35 39
   35 39 5A 30 5C 31 0B 30 09 06 03 55 04 06 13 02 55 53 31 0B 30 09 06
   03 55 04 08 0C 02 43 41 31 0B 30 09 06 03 55 04 07 0C 02 4C 41 31 14
   30 12 06 03 55 04 0A 0C 0B 65 78 61 6D 70 6C 65 20 49 6E 63 31 0C 30
   0A 06 03 55 04 0B 0C 03 49 6F 54 31 0F 30 0D 06 03 55 04 05 13 06 57
   74 31 32 33 34 30 59 30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86 48
   CE 3D 03 01 07 03 42 00 04 C8 B4 21 F1 1C 25 E4 7E 3A C5 71 23 BF 2D
   9F DC 49 4F 02 8B C3 51 CC 80 C0 3F 15 0B F5 0C FF 95 8D 75 41 9D 81
   A6 A2 45 DF FA E7 90 BE 95 CF 75 F6 02 F9 15 26 18 F8 16 A2 B2 3B 56
   38 E5 9F D9 A3 81 8A 30 81 87 30 09 06 03 55 1D 13 04 02 30 00 30 1D
   06 03 55 1D 0E 04 16 04 14 96 60 0D 87 16 BF 7F D0 E7 52 D0 AC 76 07
   77 AD 66 5D 02 A0 30 1F 06 03 55 1D 23 04 18 30 16 80 14 68 D1 65 51
   F9 51 BF C8 2A 43 1D 0D 9F 08 BC 2D 20 5B 11 60 30 0E 06 03 55 1D 0F
   01 01 FF 04 04 03 02 05 A0 30 2A 06 03 55 1D 11 04 23 30 21 A0 1F 06
   08 2B 06 01 05 05 07 08 04 A0 13 30 11 06 09 2B 06 01 04 01 B4 3B 0A
   01 04 04 01 02 03 04 30 0A 06 08 2A 86 48 CE 3D 04 03 02 03 49 00 30
   46 02 21 00 C0 D8 19 96 D2 50 7D 69 3F 3C 48 EA A5 EE 94 91 BD A6 DB
   21 40 99 D9 81 17 C6 3B 36 13 74 CD 86 02 21 00 A7 74 98 9F 4C 32 1A
   5C F2 5D 83 2A 4D 33 6A 08 AD 67 DF 20 F1 50 64 21 18 8A 0A DE 6D 34
   92 36

A.2.1.  Example C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the same X.509 certificate is
   shown below in CBOR diagnostic format.

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/This defines a CBOR Sequence (RFC 8742):/

 3,
 h'7E7661D7B54E4632',
 0,
 [
  -4, "US",
   6, "CA",
   8, "Example Inc",
   9, "certification",
   1, "802.1AR CA"
 ],
 1548934156,
 null,
 [
  -4, "US",
   6, "CA",
   5, "LA",
   8, "example Inc",
   9, "IoT",
  -3, "Wt1234"
 ],
 1,
 h'FDC8B421F11C25E47E3AC57123BF2D9FDC494F028BC351CC80C03F150BF50CFF95',
 [
   4, -2,
   1, h'96600D8716BF7FD0E752D0AC760777AD665D02A0',
   7, h'68D16551F951BFC82A431D0D9F08BC2D205B1160',
  -2, 5,
  3, [-1, [h'2B06010401B01F0A01', h'01020304']]   / subjectAltName w. hardwareModuleName /
 ],
 h'C0D81996D2507D693F3C48EAA5EE9491BDA6DB214099D98117C63B361374CD86A7
   74989F4C321A5CF25D832A4D336A08AD67DF20F1506421188A0ADE6D349236'

   The size of the CBOR encoding (CBOR sequence) is 275 bytes:

   03 48 7E 76 61 D7 B5 4E 46 32 8A 23 62 55 53 06 62 43 41 08 6B 45 78
   61 6D 70 6C 65 20 49 6E 63 09 6D 63 65 72 74 69 66 69 63 61 74 69 6F
   6E 01 6A 38 30 32 2E 31 41 52 20 43 41 1A 5C 52 DC 0C F6 8C 23 62 55
   53 06 62 43 41 05 62 4C 41 08 6B 65 78 61 6D 70 6C 65 20 49 6E 63 09
   63 49 6F 54 22 66 57 74 31 32 33 34 01 58 21 FD C8 B4 21 F1 1C 25 E4
   7E 3A C5 71 23 BF 2D 9F DC 49 4F 02 8B C3 51 CC 80 C0 3F 15 0B F5 0C
   FF 95 8A 04 21 01 54 96 60 0D 87 16 BF 7F D0 E7 52 D0 AC 76 07 77 AD
   66 5D 02 A0 07 54 68 D1 65 51 F9 51 BF C8 2A 43 1D 0D 9F 08 BC 2D 20
   5B 11 60 21 05 03 82 20 82 49 2B 06 01 04 01 B0 1F 0A 01 44 01 02 03
   04 00 58 40 C0 D8 19 96 D2 50 7D 69 3F 3C 48 EA A5 EE 94 91 BD A6 DB
   21 40 99 D9 81 17 C6 3B 36 13 74 CD 86 A7 74 98 9F 4C 32 1A 5C F2 5D
   83 2A 4D 33 6A 08 AD 67 DF 20 F1 50 64 21 18 8A 0A DE 6D 34 92 36

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A.3.  Example CAB Baseline ECDSA HTTPS X.509 Certificate

   The www.ietf.org HTTPS server replies with a certificate message with
   2 certificates.  The DER encoding of the first certificate is 1209
   bytes.

   30 82 04 b5 30 82 04 5a a0 03 02 01 02 02 10 04 7f a1 e3 19 28 ee 40
   3b a0 b8 3a 39 56 73 fc 30 0a 06 08 2a 86 48 ce 3d 04 03 02 30 4a 31
   0b 30 09 06 03 55 04 06 13 02 55 53 31 19 30 17 06 03 55 04 0a 13 10
   43 6c 6f 75 64 66 6c 61 72 65 2c 20 49 6e 63 2e 31 20 30 1e 06 03 55
   04 03 13 17 43 6c 6f 75 64 66 6c 61 72 65 20 49 6e 63 20 45 43 43 20
   43 41 2d 33 30 1e 17 0d 32 30 30 37 32 39 30 30 30 30 30 30 5a 17 0d
   32 31 30 37 32 39 31 32 30 30 30 30 5a 30 6d 31 0b 30 09 06 03 55 04
   06 13 02 55 53 31 0b 30 09 06 03 55 04 08 13 02 43 41 31 16 30 14 06
   03 55 04 07 13 0d 53 61 6e 20 46 72 61 6e 63 69 73 63 6f 31 19 30 17
   06 03 55 04 0a 13 10 43 6c 6f 75 64 66 6c 61 72 65 2c 20 49 6e 63 2e
   31 1e 30 1c 06 03 55 04 03 13 15 73 6e 69 2e 63 6c 6f 75 64 66 6c 61
   72 65 73 73 6c 2e 63 6f 6d 30 59 30 13 06 07 2a 86 48 ce 3d 02 01 06
   08 2a 86 48 ce 3d 03 01 07 03 42 00 04 96 3e cd d8 4d cd 1b 93 a1 cf
   43 2d 1a 72 17 d6 c6 3b de 33 55 a0 2f 8c fb 5a d8 99 4c d4 4e 20 5f
   15 f6 e3 d2 3b 38 2b a6 49 9b b1 7f 34 1f a5 92 fa 21 86 1f 16 d3 12
   06 63 24 05 fd 70 42 bd a3 82 02 fd 30 82 02 f9 30 1f 06 03 55 1d 23
   04 18 30 16 80 14 a5 ce 37 ea eb b0 75 0e 94 67 88 b4 45 fa d9 24 10
   87 96 1f 30 1d 06 03 55 1d 0e 04 16 04 14 cc 0b 50 e7 d8 37 db f2 43
   f3 85 3d 48 60 f5 3b 39 be 9b 2a 30 2e 06 03 55 1d 11 04 27 30 25 82
   15 73 6e 69 2e 63 6c 6f 75 64 66 6c 61 72 65 73 73 6c 2e 63 6f 6d 82
   0c 77 77 77 2e 69 65 74 66 2e 6f 72 67 30 0e 06 03 55 1d 0f 01 01 ff
   04 04 03 02 07 80 30 1d 06 03 55 1d 25 04 16 30 14 06 08 2b 06 01 05
   05 07 03 01 06 08 2b 06 01 05 05 07 03 02 30 7b 06 03 55 1d 1f 04 74
   30 72 30 37 a0 35 a0 33 86 31 68 74 74 70 3a 2f 2f 63 72 6c 33 2e 64
   69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 6c 6f 75 64 66 6c 61 72 65 49
   6e 63 45 43 43 43 41 2d 33 2e 63 72 6c 30 37 a0 35 a0 33 86 31 68 74
   74 70 3a 2f 2f 63 72 6c 34 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f
   43 6c 6f 75 64 66 6c 61 72 65 49 6e 63 45 43 43 43 41 2d 33 2e 63 72
   6c 30 4c 06 03 55 1d 20 04 45 30 43 30 37 06 09 60 86 48 01 86 fd 6c
   01 01 30 2a 30 28 06 08 2b 06 01 05 05 07 02 01 16 1c 68 74 74 70 73
   3a 2f 2f 77 77 77 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 50 53
   30 08 06 06 67 81 0c 01 02 02 30 76 06 08 2b 06 01 05 05 07 01 01 04
   6a 30 68 30 24 06 08 2b 06 01 05 05 07 30 01 86 18 68 74 74 70 3a 2f
   2f 6f 63 73 70 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 30 40 06 08 2b
   06 01 05 05 07 30 02 86 34 68 74 74 70 3a 2f 2f 63 61 63 65 72 74 73
   2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 6c 6f 75 64 66 6c 61 72
   65 49 6e 63 45 43 43 43 41 2d 33 2e 63 72 74 30 0c 06 03 55 1d 13 01
   01 ff 04 02 30 00 30 82 01 05 06 0a 2b 06 01 04 01 d6 79 02 04 02 04
   81 f6 04 81 f3 00 f1 00 76 00 f6 5c 94 2f d1 77 30 22 14 54 18 08 30
   94 56 8e e3 4d 13 19 33 bf df 0c 2f 20 0b cc 4e f1 64 e3 00 00 01 73
   9c 83 5f 8e 00 00 04 03 00 47 30 45 02 21 00 f8 d1 b4 a9 3d 2f 0d 4c
   41 76 df b4 88 bc c7 3b 86 44 3d 7d e0 0e 6a c8 17 4d 89 48 a8 84 36

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   68 02 20 29 ff 5a 34 06 8a 24 0c 69 50 27 88 e8 ee 25 ab 7e d2 cb cf
   68 6e ce 7b 5f 96 b4 31 a9 07 02 fa 00 77 00 5c dc 43 92 fe e6 ab 45
   44 b1 5e 9a d4 56 e6 10 37 fb d5 fa 47 dc a1 73 94 b2 5e e6 f6 c7 0e
   ca 00 00 01 73 9c 83 5f be 00 00 04 03 00 48 30 46 02 21 00 e8 91 c1
   97 bf b0 e3 d3 0c b6 ce e6 0d 94 c3 c7 5f d1 17 53 36 93 11 08 d8 98
   12 d4 d2 9d 81 d0 02 21 00 a1 59 d1 6c 46 47 d1 48 37 57 fc d6 ce 4e
   75 ec 7b 5e f6 57 ef e0 28 f8 e5 cc 47 92 68 2d ac 43 30 0a 06 08 2a
   86 48 ce 3d 04 03 02 03 49 00 30 46 02 21 00 bd 63 cf 4f 7e 5c fe 6c
   29 38 5e a7 1c fb fc 1e 3f 7b 1c d0 72 51 a2 21 f7 77 69 c0 f4 71 df
   ea 02 21 00 b5 c0 6c c4 58 54 fa 30 b2 82 88 b1 d3 bb 9a 66 61 ed 50
   31 72 5b 1a 82 02 e0 da 5b 59 f9 54 02

A.3.1.  Example C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the first X.509 certificate
   is shown below in CBOR diagnostic format.

/This defines a CBOR Sequence (RFC 8742):/

3,
h'047FA1E31928EE403BA0B83A395673FC',
0,
[
 -4, "US",
 -8, "Cloudflare, Inc.",
 -1, "Cloudflare Inc ECC CA-3"
],
1595980800,
1627560000,
[
 -4, "US",
 -6, "CA",
 -5, "San Francisco",
 -8, "Cloudflare, Inc.",
 -1, "sni.cloudflaressl.com"
],
1,
h'FD963ECDD84DCD1B93A1CF432D1A7217D6C63BDE3355A02F8CFB5AD8994CD44E20',
[
 7, h'A5CE37EAEBB0750E946788B445FAD9241087961F',
 1, h'CC0B50E7D837DBF243F3853D4860F53B39BE9B2A',
 3, [2, "sni.cloudflaressl.com", 2, "www.ietf.org"],
-2, 1,
 8, [1, 2],
 5, ["http://crl3.digicert.com/CloudflareIncECCCA-3.crl",
     "http://crl4.digicert.com/CloudflareIncECCCA-3.crl"],
 6, [h'6086480186FD6C0101', [1, "https://www.digicert.com/CPS"],  2],
 9, [1, "http://ocsp.digicert.com",

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     2, "http://cacerts.digicert.com/CloudflareIncECCCA-3.crt"],
-4, -2,
10, [
    h'F65C942FD1773022145418083094568EE34D131933BFDF0C2F200BCC4EF164E3',
    77922190,
    0,
    h'F8D1B4A93D2F0D4C4176DFB488BCC73B86443D7DE00E6AC8174D8948A8843668
    29FF5A34068A240C69502788E8EE25AB7ED2CBCF686ECE7B5F96B431A90702FA',
    h'5CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA',
    77922238,
    0,
    h'E891C197BFB0E3D30CB6CEE60D94C3C75FD1175336931108D89812D4D29D81D0
    A159D16C4647D1483757FCD6CE4E75EC7B5EF657EFE028F8E5CC4792682DAC43'
    ]
],
h'BD63CF4F7E5CFE6C29385EA71CFBFC1E3F7B1CD07251A221F77769C0F471DFEA
  B5C06CC45854FA30B28288B1D3BB9A6661ED5031725B1A8202E0DA5B59F95402'

   The size of the CBOR encoding (CBOR sequence) is 783 bytes.

A.4.  Example CAB Baseline RSA HTTPS X.509 Certificate

   The tools.ietf.org HTTPS server replies with a certificate message
   with 4 certificates.  The DER encoding of the first certificate is
   1647 bytes.

   30 82 06 6b 30 82 05 53 a0 03 02 01 02 02 09 00 a6 a5 5c 87 0e 39 b4
   0e 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0b 05 00 30 81 c6 31 0b 30 09
   06 03 55 04 06 13 02 55 53 31 10 30 0e 06 03 55 04 08 13 07 41 72 69
   7a 6f 6e 61 31 13 30 11 06 03 55 04 07 13 0a 53 63 6f 74 74 73 64 61
   6c 65 31 25 30 23 06 03 55 04 0a 13 1c 53 74 61 72 66 69 65 6c 64 20
   54 65 63 68 6e 6f 6c 6f 67 69 65 73 2c 20 49 6e 63 2e 31 33 30 31 06
   03 55 04 0b 13 2a 68 74 74 70 3a 2f 2f 63 65 72 74 73 2e 73 74 61 72
   66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72
   79 2f 31 34 30 32 06 03 55 04 03 13 2b 53 74 61 72 66 69 65 6c 64 20
   53 65 63 75 72 65 20 43 65 72 74 69 66 69 63 61 74 65 20 41 75 74 68
   6f 72 69 74 79 20 2d 20 47 32 30 1e 17 0d 32 30 31 30 30 31 31 39 33
   38 33 36 5a 17 0d 32 31 31 31 30 32 31 39 33 38 33 36 5a 30 3e 31 21
   30 1f 06 03 55 04 0b 13 18 44 6f 6d 61 69 6e 20 43 6f 6e 74 72 6f 6c
   20 56 61 6c 69 64 61 74 65 64 31 19 30 17 06 03 55 04 03 0c 10 2a 2e
   74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 82 01 22 30 0d 06 09 2a
   86 48 86 f7 0d 01 01 01 05 00 03 82 01 0f 00 30 82 01 0a 02 82 01 01
   00 b1 e1 37 e8 eb 82 d6 89 fa db f5 c2 4b 77 f0 2c 4a de 72 6e 3e 13
   60 d1 a8 66 1e c4 ad 3d 32 60 e5 f0 99 b5 f4 7a 7a 48 55 21 ee 0e 39
   12 f9 ce 0d ca f5 69 61 c7 04 ed 6e 0f 1d 3b 1e 50 88 79 3a 0e 31 41
   16 f1 b1 02 64 68 a5 cd f5 4a 0a ca 99 96 35 08 c3 7e 27 5d d0 a9 cf
   f3 e7 28 af 37 d8 b6 7b dd f3 7e ae 6e 97 7f f7 ca 69 4e cc d0 06 df
   5d 27 9b 3b 12 e7 e6 fe 08 6b 52 7b 82 11 7c 72 b3 46 eb c1 e8 78 b8

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   0f cb e1 eb bd 06 44 58 dc 83 50 b2 a0 62 5b dc 81 b8 36 e3 9e 7c 79
   b2 a9 53 8a e0 0b c9 4a 2a 13 39 31 13 bd 2c cf a8 70 cf 8c 8d 3d 01
   a3 88 ae 12 00 36 1d 1e 24 2b dd 79 d8 53 01 26 ed 28 4f c9 86 94 83
   4e c8 e1 14 2e 85 b3 af d4 6e dd 69 46 af 41 25 0e 7a ad 8b f2 92 ca
   79 d9 7b 32 4f f7 77 e8 f9 b4 4f 23 5c d4 5c 03 ae d8 ab 3a ca 13 5f
   5d 5d 5d a1 02 03 01 00 01 a3 82 02 e1 30 82 02 dd 30 0c 06 03 55 1d
   13 01 01 ff 04 02 30 00 30 1d 06 03 55 1d 25 04 16 30 14 06 08 2b 06
   01 05 05 07 03 01 06 08 2b 06 01 05 05 07 03 02 30 0e 06 03 55 1d 0f
   01 01 ff 04 04 03 02 05 a0 30 3d 06 03 55 1d 1f 04 36 30 34 30 32 a0
   30 a0 2e 86 2c 68 74 74 70 3a 2f 2f 63 72 6c 2e 73 74 61 72 66 69 65
   6c 64 74 65 63 68 2e 63 6f 6d 2f 73 66 69 67 32 73 31 2d 32 34 32 2e
   63 72 6c 30 63 06 03 55 1d 20 04 5c 30 5a 30 4e 06 0b 60 86 48 01 86
   fd 6e 01 07 17 01 30 3f 30 3d 06 08 2b 06 01 05 05 07 02 01 16 31 68
   74 74 70 3a 2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72
   66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72
   79 2f 30 08 06 06 67 81 0c 01 02 01 30 81 82 06 08 2b 06 01 05 05 07
   01 01 04 76 30 74 30 2a 06 08 2b 06 01 05 05 07 30 01 86 1e 68 74 74
   70 3a 2f 2f 6f 63 73 70 2e 73 74 61 72 66 69 65 6c 64 74 65 63 68 2e
   63 6f 6d 2f 30 46 06 08 2b 06 01 05 05 07 30 02 86 3a 68 74 74 70 3a
   2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72 66 69 65 6c
   64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72 79 2f 73 66
   69 67 32 2e 63 72 74 30 1f 06 03 55 1d 23 04 18 30 16 80 14 25 45 81
   68 50 26 38 3d 3b 2d 2c be cd 6a d9 b6 3d b3 66 63 30 2b 06 03 55 1d
   11 04 24 30 22 82 10 2a 2e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67
   82 0e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 1d 06 03 55 1d 0e
   04 16 04 14 ad 8a b4 1c 07 51 d7 92 89 07 b0 b7 84 62 2f 36 55 7a 5f
   4d 30 82 01 06 06 0a 2b 06 01 04 01 d6 79 02 04 02 04 81 f7 04 81 f4
   00 f2 00 77 00 f6 5c 94 2f d1 77 30 22 14 54 18 08 30 94 56 8e e3 4d
   13 19 33 bf df 0c 2f 20 0b cc 4e f1 64 e3 00 00 01 74 e5 ac 71 13 00
   00 04 03 00 48 30 46 02 21 00 8c f5 48 52 ce 56 35 43 39 11 cf 10 cd
   b9 1f 52 b3 36 39 22 3a d1 38 a4 1d ec a6 fe de 1f e9 0f 02 21 00 bc
   a2 25 43 66 c1 9a 26 91 c4 7a 00 b5 b6 53 ab bd 44 c2 f8 ba ae f4 d2
   da f2 52 7c e6 45 49 95 00 77 00 5c dc 43 92 fe e6 ab 45 44 b1 5e 9a
   d4 56 e6 10 37 fb d5 fa 47 dc a1 73 94 b2 5e e6 f6 c7 0e ca 00 00 01
   74 e5 ac 72 3c 00 00 04 03 00 48 30 46 02 21 00 a5 e0 90 6e 63 e9 1d
   4f dd ef ff 03 52 b9 1e 50 89 60 07 56 4b 44 8a 38 28 f5 96 dc 6b 28
   72 6d 02 21 00 fc 91 ea ed 02 16 88 66 05 4e e1 8a 2e 53 46 c4 cc 51
   fe b3 fa 10 a9 1d 2e db f9 91 25 f8 6c e6 30 0d 06 09 2a 86 48 86 f7
   0d 01 01 0b 05 00 03 82 01 01 00 14 04 3f a0 be d2 ee 3f a8 6e 3a 1f
   78 8e a0 4c 35 53 0f 11 06 1f ff 60 a1 6d 0b 83 e9 d9 2a db b3 3f 9d
   b3 d7 e0 59 4c 19 a8 e4 19 a5 0c a7 70 72 77 63 d5 fe 64 51 0a d2 7a
   d6 50 a5 8a 92 38 ec cb 2f 0f 5a c0 64 58 4d 5c 06 b9 73 63 68 27 8b
   89 34 dc 79 c7 1d 3a fd 34 5f 83 14 41 58 49 80 68 29 80 39 8a 86 72
   69 cc 79 37 ce e3 97 f7 dc f3 95 88 ed 81 03 29 00 d2 a2 c7 ba ab d6
   3a 8e ca 09 0b d9 fb 39 26 4b ff 03 d8 8e 2d 3f 6b 21 ca 8a 7d d8 5f
   fb 94 ba 83 de 9c fc 15 8d 61 fa 67 2d b0 c7 db 3d 25 0a 41 4a 85 d3
   7f 49 46 37 3c f4 b1 75 d0 52 f3 dd c7 66 f1 4b fd aa 00 ed bf e4 7e
   ed 01 ec 7b e4 f6 46 fc 31 fd 72 fe 03 d2 f2 65 af 4d 7e e2 81 9b 7a

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   fd 30 3c f5 52 f4 05 34 a0 8a 3e 19 41 58 c8 a8 e0 51 71 84 09 15 ae
   ec a5 77 75 fa 18 f7 d5 77 d5 31 cc c7 2d

A.4.1.  Example C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the first X.509 certificate
   is shown below in CBOR diagnostic format.

/This defines a CBOR Sequence (RFC 8742):/

3,
h'A6A55C870E39B40E',
23,
[
 -4, "US",
 -6, "Arizona",
 -5, "Scottsdale",
 -8, "Starfield Technologies, Inc.",
 -9, "http://certs.starfieldtech.com/repository/",
 -1, "Starfield Secure Certificate Authority - G2"
],
1601581116,
1635881916,
[
  -9, "Domain Control Validated",
   1, "*.tools.ietf.org"
],
0,
h'B1E137E8EB82D689FADBF5C24B77F02C4ADE726E3E1360D1A8661EC4AD3D3260
  E5F099B5F47A7A485521EE0E3912F9CE0DCAF56961C704ED6E0F1D3B1E508879
  3A0E314116F1B1026468A5CDF54A0ACA99963508C37E275DD0A9CFF3E728AF37
  D8B67BDDF37EAE6E977FF7CA694ECCD006DF5D279B3B12E7E6FE086B527B8211
  7C72B346EBC1E878B80FCBE1EBBD064458DC8350B2A0625BDC81B836E39E7C79
  B2A9538AE00BC94A2A13393113BD2CCFA870CF8C8D3D01A388AE1200361D1E24
  2BDD79D8530126ED284FC98694834EC8E1142E85B3AFD46EDD6946AF41250E7A
  AD8BF292CA79D97B324FF777E8F9B44F235CD45C03AED8AB3ACA135F5D5D5DA1',
[
-4, -2,
 8, [ 1, 2 ],
 -2, 5,
 5, ["http://crl.starfieldtech.com/sfig2s1-242.crl"],
 6, [ h'6086480186fd6e01071701',
      [1, "http://certificates.starfieldtech.com/repository/"], 1 ],
 9, [ 1, "http://ocsp.starfieldtech.com/",
      2, "http://certificates.starfieldtech.com/repository/sfig2.crt" ],
 7, h'254581685026383D3B2D2CBECD6AD9B63DB36663',
 3, [ 2, "*.tools.ietf.org", 2, "tools.ietf.org" ],
 1, h'AD8AB41C0751D7928907B0B784622F36557A5F4D',

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10, [
    h'F65C942FD1773022145418083094568EE34D131933BFDF0C2F200BCC4EF164E3',
    1715,
    0,
    h'8CF54852CE5635433911CF10CDB91F52B33639223AD138A41DECA6FEDE1FE90F
      BCA2254366C19A2691C47A00B5B653ABBD44C2F8BAAEF4D2DAF2527CE6454995',
    h'5CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA',
    2012,
    0,
    h'A5E0906E63E91D4FDDEFFF0352B91E50896007564B448A3828F596DC6B28726D
      FC91EAED02168866054EE18A2E5346C4CC51FEB3FA10A91D2EDBF99125F86CE6'
    ]
],
h'14043FA0BED2EE3FA86E3A1F788EA04C35530F11061FFF60A16D0B83E9D92ADB
  B33F9DB3D7E0594C19A8E419A50CA770727763D5FE64510AD27AD650A58A9238
  ECCB2F0F5AC064584D5C06B9736368278B8934DC79C71D3AFD345F8314415849
  80682980398A867269CC7937CEE397F7DCF39588ED81032900D2A2C7BAABD63A
  8ECA090BD9FB39264BFF03D88E2D3F6B21CA8A7DD85FFB94BA83DE9CFC158D61
  FA672DB0C7DB3D250A414A85D37F4946373CF4B175D052F3DDC766F14BFDAA00
  EDBFE47EED01EC7BE4F646FC31FD72FE03D2F265AF4D7EE2819B7AFD303CF552
  F40534A08A3E194158C8A8E05171840915AEECA57775FA18F7D577D531CCC72D'

   The size of the CBOR encoding (CBOR sequence) is 1245 bytes.

Acknowledgments

   The authors want to thank Henk Birkholz, Carsten Bormann, Russ
   Housley, Olle Johansson, Benjamin Kaduk, Ilari Liusvaara, Laurence
   Lundblade, Francesca Palombini, Thomas Peterson, Michael Richardson,
   Stefan Santesson, Jim Schaad, Brian Sipos, Fraser Tweedale, and Rene
   Struik for reviewing and commenting on intermediate versions of the
   draft and helping with GitHub.  The authors are especially grateful
   to Lijun Liao for his many detailed improvement proposals.

Authors' Addresses

   John Preuß Mattsson
   Ericsson AB
   Email: john.mattsson@ericsson.com

   Göran Selander
   Ericsson AB
   Email: goran.selander@ericsson.com

   Shahid Raza
   RISE AB

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   Email: shahid.raza@ri.se

   Joel Höglund
   RISE AB
   Email: joel.hoglund@ri.se

   Martin Furuhed
   Nexus Group
   Email: martin.furuhed@nexusgroup.com

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