Network Working Group S. Raza
Internet-Draft J. Hoeglund
Intended status: Standards Track RISE AB
Expires: May 19, 2021 G. Selander
J. Mattsson
Ericsson AB
M. Furuhed
Nexus Group
November 15, 2020
CBOR Encoding of X.509 Certificates (CBOR Certificates)
draft-mattsson-cose-cbor-cert-compress-03
Abstract
This document specifies a CBOR encoding of PKIX profiled X.509
Certificates. The resulting certificates are called "CBOR
certificates". The CBOR encoding supports a large subset of RFC
5280, while at the same time producing very small sizes for
certificates compatible with RFC 7925. The CBOR encoding can be used
to compress DER encoded X.509 certificated to encode natively signed
certificated. When uses to compress DER encoded X.509 certificates,
the CBOR encoding can in many cases compress RFC 7925 profiled
certificates with over 50%. The document also specifies COSE headers
for CBOR certificates as well as a TLS certificate type for CBOR
certificates.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 19, 2021.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 4
3. CBOR Encoding . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Message Fields . . . . . . . . . . . . . . . . . . . . . 5
3.2. Encoding of Extensions . . . . . . . . . . . . . . . . . 9
4. Compliance Requirements for Constrained IoT . . . . . . . . . 10
5. Deployment settings . . . . . . . . . . . . . . . . . . . . . 10
6. Expected Certificate Sizes . . . . . . . . . . . . . . . . . 11
7. Natively Signed CBOR Certificates . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9.1. CBOR Certificate Types Registry . . . . . . . . . . . . . 12
9.2. CBOR Attribute Type Registry . . . . . . . . . . . . . . 13
9.3. CBOR Extension Type Registry . . . . . . . . . . . . . . 13
9.4. CBOR Extended Key Usage Registry . . . . . . . . . . . . 14
9.5. CBOR Subject Alternative Name Registry . . . . . . . . . 15
9.6. CBOR Certificate Signature Algorithms Registry . . . . . 15
9.7. CBOR Certificate Public Key Algorithms Registry . . . . . 16
9.8. COSE Header Parameters Registry . . . . . . . . . . . . . 17
9.9. TLS Certificate Types Registry . . . . . . . . . . . . . 17
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. Example CBOR Certificates . . . . . . . . . . . . . 20
A.1. Example RFC 7925 profiled X.509 Certificate . . . . . . . 20
A.2. Example HTPPS X.509 Certificate . . . . . . . . . . . . . 22
Appendix B. X.509 Certificate Profile, ASN.1 . . . . . . . . . . 25
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
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1. Introduction
One of the challenges with deploying a Public Key Infrastructure
(PKI) for the Internet of Things (IoT) is the size and encoding of
X.509 public key certificates [RFC5280], since those are not
optimized for constrained environments [RFC7228]. More compact
certificate representations are desirable. 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) [RFC7049] reduces the certificate size
significantly which has known performance benefits in terms of
decreased communication overhead, power consumption, latency,
storage, etc.
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. [RFC8610] 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 [RFC7049], [RFC8610], and
[RFC8742].
RFC 7925 [RFC7925] specifies a certificate profile for Internet of
Things deployments which can be applied for lightweight certificate
based authentication with e.g. TLS [RFC8446], DTLS
[I-D.ietf-tls-dtls13], COSE [RFC8152], or EDHOC
[I-D.ietf-lake-edhoc]. This document specifies a CBOR encoding which
can support large parts of [RFC5280] based on [X.509-IoT]. The
encoding support all [RFC7925] profiled X.509 certificates. Two
variants are defined using the same CBOR encoding and differing only
in what is being signed:
o CBOR compression of DER encoded X.509 certificates [RFC5280],
which can be decompressed into the original DER encoded X.509
certificate.
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o Natively signed CBOR certificates, which further optimizes the
performance in constrained environments but is not backwards
compatible with [RFC5280], see Section 7.
This document specifies COSE headers for use of the CBOR certificates
with COSE, see Section 9.8. The document also specifies a TLS
certificate type for use of the CBOR certificates with TLS (with or
without additional TLS certificate compression), see Section 9.9.
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 [RFC5280],
[RFC7049], [RFC7228], and [RFC8610].
3. CBOR Encoding
This section specifies the content and encoding for CBOR
certificates, with the overall objective to produce a very compact
representation supporting large parts of [RFC5280] and everything in
[RFC7925]. In the CBOR encoding, static fields are elided, elliptic
curve points are compressed, OID are replaced with short integers,
time values are compressed, and redundant encoding is removed.
Combining these different components reduces the certificate size
significantly, which is not possible with general purpose
compressions algorithms, see Figure 1.
The CBOR certificate can be either a CBOR compressed 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 signed
CBOR certificate, in which case the signature is calculated directly
on the CBOR encoded data (see Section 7). In both cases the
certificate content is adhering to the restrictions given by
[RFC5280]. When used as for compression of an existing X.509
certificate, the encoding only works on canonical encoded
certificates. The encoding is known to work with DER but might work
with other canonical encodings. The compression 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.
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3.1. Message Fields
The X.509 fields and their CBOR encodings are listed below.
CBOR certificates are defined in terms of DER encoded [RFC5280] X.509
certificates:
o version. The 'version' field is known (fixed to v3) and is
omitted in the CBOR encoding.
o serialNumber. The 'serialNumber' INTEGER value field is encoded
as a CBOR byte string 'certificateSerialNumber'. Any leading 0x00
byte (to indicate that the number is not negative) is omitted.
o signatureAlgorithm. The 'signatureAlgorithm' field is encoded as
a CBOR int 'issuerSignatureAlgorithm' (see Section 9.6) or a
relativeOID byte string. Algorithms with parameters are not
supported except RSA algorithms that use parameters = NULL.
o signature. The 'signature' field is always the same as the
'signatureAlgorithm' field and always omitted from the CBOR
encoding.
o issuer. In the general case, the sequence of
'RelativeDistinguishedName' is encoded as CBOR array of CBOR
arrays of Attributes, where each Attribute type and value is
encoded as a (CBOR int, CBOR text string) pair. Each
AttributeType is encoded as a CBOR int (see Figure 3), where the
sign is used to represent the character string type; positive for
printableString, negative for utf8String. The string types
teletexString, universalString, and bmpString are not supported.
If exactly one 'RelativeDistinguishedName' is present, the outer
array is omitted, and issuer is encoded as a single CBOR array.
If a RelativeDistinguishedName contains a single Attribute
containing an utf8String encoded 'common name', the int is omitted
and the Attribute is encoded as a single CBOR text string. If the
utf8String encoded 'common name' contains an EUI-64 mapped from a
48-bit MAC address (i.e. of the form "hh-hh-hh-FF-FE-hh-hh-hh) it
is encoded as a CBOR byte string of length 6. Other EUI-64 is
encoded as a CBOR byte string of length 8.
o validity. The 'notBefore' and 'notAfter' fields are ASCII string
of the form "yymmddHHMMSSZ" for UTCTime and "yyyymmddHHMMSSZ" for
GeneralizedTime. They are encoded as unsigned integers using the
following invertible encoding (Horner's method with different
bases).
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n = SS + 61 * (MM + 60 * (HH + 24 * (dd + 32 * (mm + 13 *
(yy)yy))))
They are encoded as a byte string, which is interpreted as an
unsigned integer n in network byte order. UTCTime and
GeneralizedTime are encoded as a byte strings of length 4 and 5
respectively. Decoding can be done by a succession of modulo and
subtraction operations. I.e. SS = n mod 61, MM = ((n - SS) / 61)
mod 60, etc.
o subject. The 'subject' is encoded exactly like issuer.
o subjectPublicKeyInfo. The 'algorithm' field is encoded as the
CBOR int 'subjectPublicKeyAlgorithm' (see Section 9.7) or a
relativeOID byte string. Algorithms with parameters are not
supported except id-ecPublicKey with named curves and the RSA
algorithms that use parameters = NULL. For id-ecPublicKey the
namedCurve parameter is encoded in the CBOR int. 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. Uncompressed
public keys of type id-ecPublicKey are point compressed as defined
in Section 2.3.3 of [SECG].
If a DER encoded certificate with a point compressed public key of
type id-ecPublicKey is comreseed, the octets 0xfe and 0xfd are
used instead of 0x02 and 0x03 in the CBOR encoding to represent a
even and off y-coordinate respectively.
o extensions. The 'extensions' field is encoded as a CBOR array
where each extension is encoded as either a registered extension
(an CBOR int followed by an optional CBOR item of any type) or a
raw extension (a relative OID byte string, a bool, and a the DER
encoved value of 'extnValue'). If the array contains exactly one
int, the array is omitted. Extensions are encoded as specified in
Section 3.2. The extensions mandated to be supported by [RFC7925]
are given special treatment.
o signatureValue. 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. ECDSA signatures are given special
treatment. For ECDSA signatures the SEQUENCE and INTEGER type and
length fields are omitted and the two INTEGER value fields are
padded to the fixed length L = ceil( log2(n) / 8 ), where n is the
size of the largest prime-order subgroup. For secp256r1,
secp384r1, and secp521r1, L is 32, 48, and 66 respectively. For
natively signed CBOR certificates the signatureValue is calculated
over the CBOR sequence TBSCertificate.
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In addition to the above fields present in X.509, the CBOR encoding
introduces an additional field:
o cborCertificateType. A CBOR int used to indicate the type of CBOR
certificate. Currently, type can be a natively signed CBOR
certificate (cborCertificateType = 0) or a CBOR compressed X.509
certificates (cborCertificateType = 1), see Section 9.1.
The following Concise Data Definition Language (CDDL) defines
CBORCertificate and TBSCertificate, which are encoded as CBOR
Sequences [RFC8742]. The member names therefore only have
documentary value.
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; This defines an array, the elements of which are to be used in a CBOR Sequence:
CBORCertificate = [
TBSCertificate,
issuerSignatureValue : bytes,
]
TBSCertificate = (
cborCertificateType : int,
certificateSerialNumber : bytes,
issuerSignatureAlgorithm : Algorithm,
issuer : Name,
validityNotBefore : bytes,
validityNotAfter : bytes,
subject : Name,
subjectPublicKeyAlgorithm : Algorithm,
subjectPublicKey : bytes,
extensions : [ * Extension ] / int,
)
Algorithm = int / relativeOID
relativeOID = bytes
Name = [ * RelativeDistinguishedName ] / RelativeDistinguishedName
RelativeDistinguishedName = [ + Attribute ] / text / bytes
Attribute = (
attributeType : int,
attributeValue : text,
)
Extension = ExtensionReg // ExtensionRaw
ExtensionReg = (
extensionType : int,
? extensionValue : any, ; optionality and type known from extensionType
)
ExtensionRaw = (
extensionID : relativeOID,
? critical : bool,
? extensionValue : bytes,
)
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3.2. Encoding of Extensions
EDITOR'S NOTE: The current specification encodes many common
extensions with a DER encoded byte string. It should be discussed if
more or all commonly active extensions should be natively encoded
with CBOR. Would an specific CBOR encoding have to be specified for
each extension or can a general CBOR encoding that apply to all
remaining extensions be specified?
This section details the encoding of the 'extensions' field. The
'extensions' field is encoded as a CBOR array where each extension is
encoded as either a registered extension (an CBOR int followed by an
optional CBOR item of any type) or a raw extension (a relative OID
byte string, a bool, and a the DER encoved value of 'extnValue').
For registered extensions each 'extnID' field is encoded as a CBOR
int (see Section 9.3), where the sign is used to encode if the
extension 'critical' field. Critical extensions are encoded with a
positive sign and non-critical extensions are encoded with a negative
sign. If the array contains exactly one int, the array is omitted.
The 'extnValue' OCTET STREAM value field is encoded as the CBOR byte
string 'extensionValue' except for the extensions specified below.
The extensions mandated to be supported by [RFC7925] are given
special treatment. Below the boolean values (cA, digitalSignature,
keyAgreement, etc.) are set to 0 or 1 according to their value in the
DER encoding.:
o basicConstraints. A basic constrained with 'cA' = false is
encoded as extensionType = 1, a basic constrained with 'cA' = true
without 'pathLenConstraint' is encoded as extensionType = 2, and a
basic constrained with 'cA' = true with 'pathLenConstraint' is
encoded as extensionType = 3 followed by and int extensionValue
encoding the value of 'pathLenConstraint'.
o keyUsage. The extensionType is encoded as below. If none of the
bits except digitalSignature, keyAgreement, and keyCertSign are
set, the extensionValue is omitted. Otherwise the 'KeyUsage' BIT
STRING is interpreted as an unsigned integer n in network byte
order and encoded as a CBOR int.
extensionType = 4 + digitalSignature
+ 2 * keyAgreement + 4 * keyCertSign
o extKeyUsage. extensionType is encoded as defined by Section 9.3
and extensionValue is encoded as an array of ints or relativeOID
where each ints or relativeOID encodes a key usage purpose (see
Section 9.4 for registered ints). If the array contains a single
item, the array is omitted.
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extensionValue = [ * int / relativeOID ] / int / relativeOID
o subjectAltName. extensionType is encoded as defined by Section 9.3
and extensionValue is encoded as an [ * ( int, any ) ] array where
each (int, any) pair encodes a general name (see Section 9.5). If
subjectAltName contains exactly one dNSName, the array and the int
are omitted and extensionValue is the dNSName encoded as a CBOR
text string.
Consequently:
o A critical basicConstraints (cA = 1) without pathLenConstraint is
encoded as the CBOR int -2.
o A non-critical keyUsage with only keyAgreement asserted is encoded
as the CBOR int 6 (= 4 + 2).
o A non-critical extKeyUsage containing id-kp-codeSigning and id-kp-
OCSPSigning is encoded as the CBOR int 12 followed by the CBOR
array [ 3, 6 ].
o A non-critical subjectAltName containing only the dNSName
example.com is encoded as the CBOR int 13 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 [ -2, 6, 12, [ 3, 6 ], 13, "example.com" ].
4. Compliance Requirements for Constrained IoT
For general purpose applications, the normative requirements of
[RFC5280] applies. This section describes the mandatory to implement
algorithms and OIDs for constrained IoT application; the values of
the OIDs including certificate fields and extensions, time format,
attributes in distinguished names, etc.
TODO: Write this section
5. Deployment settings
CBOR certificates can be deployed with legacy X.509 certificates and
CA infrastructure. In order to verify the signature, the CBOR
certificate is used to recreate the original X.509 data structure to
be able 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
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different locations depending on the deployment setting. For
example, the mapping between CBOR 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 CBOR 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
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 CBOR
certificate and does not perform the conversion to X.509. This
option is viable when client authentication can be asserted by other
means.
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.
6. Expected Certificate Sizes
The CBOR encoding of the sample certificate given in Appendix A
results in the numbers shown in Figure 1. After [RFC7925] 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 will be small, mainly
corresponding to making the ASN.1 encoding more compact. The zlib
number was calculated with zlib-flate.
zlib-flate -compress < cert.der > cert.compressed
+------------------+--------------+------------+--------------------+
| | RFC 7925 | zlib | CBOR Certificate |
+------------------+---------------------------+--------------------+
| Certificate Size | 314 | 295 | 138 |
+------------------+--------------+------------+--------------------+
Figure 1: Comparing Sizes of Certificates (bytes)
7. Natively Signed CBOR Certificates
The difference between CBOR compressed X.509 certificate and natively
signed CBOR certificate is that the signature is calculated over the
CBOR encoding of the CBOR sequence TBSCertficate rather than the DER
encoded ASN.1 data. This removes entirely the need for ASN.1 DER and
base64 encoding which reduces the processing in the authenticating
devices and avoids known complexities with these encoding.
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Natively signed CBOR certificates can be applied in devices that are
only required to authenticate to natively signed CBOR certificate
compatible servers. This is not a major restriction for many IoT
deployments, where the parties issuing and verifying certificates can
be a restricted ecosystem which not necessarily involves public CAs.
CBOR compressed X.509 certificates provides an intermediate step
between [RFC7925] profiled X.509 certificates and natively signed
CBOR certificates: An implementation of CBOR compressed X.509
certificates contains both the CBOR encoding of the X.509 certificate
and the signature operations sufficient for natively signed CBOR
certificates.
The natively signed approach based on DER encoded X.509 certificates
described in this document has a lot of benefits. A CA can use
existing ASN.1 machinery to create a DER encoded certificate, the DER
encoded certificate can then be transformed to CBOR before signing.
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.
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 5 requires unencrypted certificates and
is not recommended.
9. IANA Considerations
For all items, the 'Reference' field points to this document.
9.1. CBOR Certificate Types Registry
IANA has created a new registry titled "CBOR Certificate Types" under
the new heading "CBOR Certificate". For values in the interval [-24,
23] the registration procedure is "IETF Review". For all other
values the registration procedure is "Expert Review". The columns of
the registry are Value, Description, and Reference, where Value is an
integer, and the other columns are text strings. The initial
contents of the registry are:
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+-------+---------------------------------------+
| Value | Description |
+=======+=======================================+
| 0 | Natively Signed CBOR Certificate |
| 1 | CBOR Compressed X.509 Certificate |
+-------+---------------------------------------+
Figure 2: CBOR Certificate Types
9.2. CBOR Attribute Type Registry
IANA has created a new registry titled "CBOR Attribute Type Registry"
under the new heading "CBOR Certificate". The columns of the
registry are Value, X.509 Attribute Type, and Reference, where Value
is an integer, and the other columns are text strings. Only positive
values can be registered. For values in the interval [1, 23] the
registration procedure is "IETF Review". For all other values the
registration procedure is "Expert Review". The initial contents of
the registry are:
+-------+---------------------------------------+
| Value | X.509 Attribute Type |
+=======+=======================================+
| 1 | id-at-commonName |
| 2 | id-at-surname |
| 3 | id-at-serialNumber |
| 4 | id-at-countryName |
| 5 | id-at-localityName |
| 6 | id-at-stateOrProvinceName |
| 7 | id-at-organizationName |
| 8 | id-at-organizationalUnitName |
| 9 | id-at-title |
| 10 | id-at-givenName |
| 11 | id-at-initials |
| 12 | id-at-generationQualifier |
| 13 | id-at-dnQualifier |
| 14 | id-at-pseudonym |
+-------+---------------------------------------+
Figure 3: CBOR Attribute Type Registry
9.3. CBOR Extension Type Registry
IANA has created a new registry titled "CBOR Extension Type Registry"
under the new heading "CBOR Certificate". The columns of the
registry are Value, X.509 Extension Type, and Reference, where Value
is an integer, and the other columns are text strings. Only positive
values can be registered. For values in the interval [1, 23] the
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registration procedure is "IETF Review". For all other values the
registration procedure is "Expert Review". The initial contents of
the registry are:
+-------+-------------------------------------+------------------+
| Value | X.509 Extension Type | extensionValue |
+=======+=====================================+==================+
| 1 | id-ce-basicConstraints (cA = false) | |
| 2 | id-ce-basicConstraints (cA = true) | |
| 3 | id-ce-basicConstraints (cA = true) | int |
| 4 | id-ce-keyUsage | int |
| 5 | id-ce-keyUsage + 1 | |
| 6 | id-ce-keyUsage + 16 | |
| 7 | id-ce-keyUsage + 17 | |
| 8 | id-ce-keyUsage + 32 | |
| 9 | id-ce-keyUsage + 33 | |
| 10 | id-ce-keyUsage + 48 | |
| 11 | id-ce-keyUsage + 49 | |
| 12 | id-ce-extKeyUsage | [] / int / rOID |
| 13 | id-ce-subjectAltName | [] / text |
| 14 | id-ce-authorityKeyIdentifier | bytes |
| 15 | id-ce-subjectKeyIdentifier | bytes |
| 16 | id-ce-certificatePolicies | bytes |
| 17 | id-ce-cRLDistributionPoints | bytes |
| 18 | id-pe-authorityInfoAccess | bytes |
| 19 | SCT List (1.3.6.1.4.1.11129.2.4.2) | bytes |
| 248 | id-ce-nameConstraints | bytes |
| 249 | id-ce-policyConstraints | bytes |
| 250 | id-ce-inhibitAnyPolicy | bytes |
| 251 | id-ce-authorityKeyIdentifier | bytes |
| 252 | id-ce-policyMappings | bytes |
| 253 | id-ce-issuerAltName | bytes |
| 254 | id-ce-subjectDirectoryAttributes | bytes |
| 255 | id-ce-freshestCRL | bytes |
| 256 | id-pe-subjectInfoAccess | bytes |
+-------+-------------------------------------+------------------+
Figure 4: CBOR Extension Type Registry
9.4. CBOR Extended Key Usage Registry
IANA has created a new registry titled "CBOR Extended Key Usage
Registry" under the new heading "CBOR Certificate". The columns of
the registry are Value, Extended Key Usage Purpose, 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". For all other values the registration procedure is
"Expert Review". The initial contents of the registry are:
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+-------+---------------------------------------+
| Value | Extended Key Usage |
+=======+=======================================+
| 0 | anyExtendedKeyUsage |
| 1 | id-kp-serverAuth |
| 2 | id-kp-clientAuth |
| 3 | id-kp-codeSigning |
| 4 | id-kp-emailProtection |
| 5 | id-kp-timeStamping |
| 6 | id-kp-OCSPSigning |
+-------+---------------------------------------+
Figure 5: CBOR Extended Key Usage Registry
9.5. CBOR Subject Alternative Name Registry
IANA has created a new registry titled "CBOR Subject Alternative Name
Registry" under the new heading "CBOR Certificate". The columns of
the registry are Value, Extended Key Usage Purpose, 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". For all other values the registration procedure is
"Expert Review". The initial contents of the registry are:
+-------+-----------------------------------+------------------+
| Value | Subject Alternative Name | |
+=======+===================================+==================+
| 0 | rfc822Name | text |
| 1 | dNSName | text |
| 2 | directoryName | Name |
| 3 | uniformResourceIdentifier | text |
| 4 | iPAddress | bytes |
+-------+-----------------------------------+------------------+
Figure 6: CBOR Subject Alternative Name Registry
9.6. CBOR Certificate Signature Algorithms Registry
IANA has created a new registry titled "CBOR Certificate Signature
Algorithms" under the new heading "CBOR Certificate". For values in
the interval [-24, 23] the registration procedure is "IETF Review".
For all other values the registration procedure is "Expert Review".
The columns of the registry are Value, X.509 Algorithm, and
Reference, where Value is an integer, and the other columns are text
strings. The initial contents of the registry are:
EDITOR'S NOTE: This is probably to many algorithms. All sha224,
sha3, and maybe ecdsa-with-SHA1 can probably be removed.
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+-------+---------------------------------------+
| Value | X.509 Signature Algorithm |
+=======+=======================================+
| 0 | sha1WithRSAEncryption |
| 1 | sha256WithRSAEncryption |
| 2 | sha384WithRSAEncryption |
| 3 | sha512WithRSAEncryption |
| 4 | id-RSASSA-PSS-SHAKE128 |
| 5 | id-RSASSA-PSS-SHAKE256 |
| 6 | ecdsa-with-SHA256 |
| 7 | ecdsa-with-SHA384 |
| 8 | ecdsa-with-SHA512 |
| 9 | id-ecdsa-with-shake128 |
| 10 | id-ecdsa-with-shake256 |
| 11 | id-Ed25519 |
| 12 | id-Ed448 |
| 13 | id-alg-hss-lms-hashsig |
| 14 | id-alg-xmss |
| 15 | id-alg-xmssmt |
| 245 | sha224WithRSAEncryption |
| 246 | id-rsassa-pkcs1-v1_5-with-sha3-224 |
| 247 | id-rsassa-pkcs1-v1_5-with-sha3-256 |
| 248 | id-rsassa-pkcs1-v1_5-with-sha3-384 |
| 249 | id-rsassa-pkcs1-v1_5-with-sha3-512 |
| 250 | ecdsa-with-SHA1 |
| 251 | ecdsa-with-SHA224 |
| 252 | id-ecdsa-with-sha3-224 |
| 253 | id-ecdsa-with-sha3-256 |
| 254 | id-ecdsa-with-sha3-384 |
| 255 | id-ecdsa-with-sha3-512 |
+-------+---------------------------------------+
Figure 7: CBOR Certificate Signature Algorithms
9.7. CBOR Certificate Public Key Algorithms Registry
IANA has created a new registry titled "CBOR Certificate Public Key
Algorithms" under the new heading "CBOR Certificate". For values in
the interval [-24, 23] the registration procedure is "IETF Review".
For all other values the registration procedure is "Expert Review".
The columns of the registry are Value, X.509 Algorithm, and
Reference, where Value is an integer, and the other columns are text
strings. The initial contents of the registry are:
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+-------+---------------------------------------+
| Value | X.509 Public Key Algorithm |
+=======+=======================================+
| 0 | rsaEncryption |
| 1 | id-ecPublicKey + secp256r1 |
| 2 | id-ecPublicKey + secp384r1 |
| 3 | id-ecPublicKey + secp521r1 |
| 4 | id-X25519 |
| 5 | id-X448 |
| 6 | id-Ed25519 |
| 7 | id-Ed448 |
| 8 | id-alg-hss-lms-hashsig |
| 9 | id-alg-xmss |
| 10 | id-alg-xmssmt |
+-------+---------------------------------------+
Figure 8: CBOR Certificate Public Key Algorithms
9.8. COSE Header Parameters Registry
This document registers the following entries in the "COSE Header
Parameters" registry under the "CBOR Object Signing and Encryption
(COSE)" heading. The formatting and processing are the same as the
corresponding x5bag, x5chain, x5t, and x5u defined in
[I-D.ietf-cose-x509] except that the certificates are CBOR encoded
instead of DER encoded.
+-----------+-------+----------------+---------------------+
| Name | Label | Value Type | Description |
+===========+=======+================+=====================+
| c5bag | TBD1 | COSE_CBOR_Cert | An ordered chain of |
| | | | CBOR certificates |
+-----------+-------+----------------+---------------------+
| c5chain | TBD2 | COSE_CBOR_Cert | An ordered chain of |
| | | | CBOR certificates |
+-----------+-------+----------------+---------------------+
| c5t | TBD3 | COSE_CertHash | Hash of an |
| | | | CBOR certificate |
+-----------+-------+----------------+---------------------+
| c5u | TBD4 | uri | URI pointing to a |
| | | | CBOR certificate |
+-----------+-------+----------------+---------------------+
9.9. TLS Certificate Types Registry
This document registers the following entry in the "TLS Certificate
Types" registry under the "Transport Layer Security (TLS) Extensions"
heading.
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EDITOR'S NOTE: The TLS registrations should be discussed and approved
by the TLS WG at a later stage. When COSE WG has adopted work on
CBOR certificates, it could perhaps be presented in the TLS WG. The
TLS WG might e.g. want a separate draft in the TLS WG.
+-------+------------------+-------------+---------+
| Value | Name | Recommended | Comment |
+=======+==================+=============+=========+
| TBD3 | CBOR Certificate | Y | |
+-------+------------------+-------------+---------+
10. References
10.1. Normative References
[I-D.ietf-tls-certificate-compression]
Ghedini, A. and V. Vasiliev, "TLS Certificate
Compression", draft-ietf-tls-certificate-compression-10
(work in progress), January 2020.
[I-D.ietf-tls-dtls13]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
1.3", draft-ietf-tls-dtls13-39 (work in progress),
November 2020.
[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>.
[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>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[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>.
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[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>.
[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>.
[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>.
[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>.
[RFC8742] Bormann, C., "Concise Binary Object Representation (CBOR)
Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020,
<https://www.rfc-editor.org/info/rfc8742>.
10.2. Informative References
[I-D.ietf-cose-x509]
Schaad, J., "CBOR Object Signing and Encryption (COSE):
Header parameters for carrying and referencing X.509
certificates", draft-ietf-cose-x509-07 (work in progress),
September 2020.
[I-D.ietf-lake-edhoc]
Selander, G., Mattsson, J., and F. Palombini, "Ephemeral
Diffie-Hellman Over COSE (EDHOC)", draft-ietf-lake-
edhoc-01 (work in progress), August 2020.
[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>.
[SECG] "Elliptic Curve Cryptography, Standards for Efficient
Cryptography Group, ver. 2", 2009,
<https://secg.org/sec1-v2.pdf>.
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[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 CBOR Certificates
A.1. Example RFC 7925 profiled X.509 Certificate
Example of [RFC7925] profiled X.509 certificate parsed with OpenSSL.
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 2020 GMT
Not After : Feb 2 00:00:00 2021 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:ae:4c:db:01:f6:14:de:fc:71:21:28:5f:dc:7f:
5c:6d:1d:42:c9:56:47:f0:61:ba:00:80:df:67:88:
67:84:5e:e9:a6:9f:d4:89:31:49:da:e3:d3:b1:54:
16:d7:53:2c:38:71:52:b8:0b:0d:f3:e1:af:40:8a:
95:d3:07:1e:58
ASN1 OID: prime256v1
NIST CURVE: P-256
X509v3 extensions:
X509v3 Key Usage:
Digital Signature
Signature Algorithm: ecdsa-with-SHA256
30:44:02:20:37:38:73:ef:87:81:b8:82:97:ef:23:5c:1f:ac:
cf:62:da:4e:44:74:0d:c2:a2:e6:a3:c6:c8:82:a3:23:8d:9c:
02:20:3a:d9:35:3b:a7:88:68:3b:06:bb:48:fe:ca:16:ea:71:
17:17:34:c6:75:c5:33:2b:2a:f1:cb:73:38:10:a1:fc
The DER encoding of the above certificate is 314 bytes.
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30 82 01 36 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 30 30 31 30 31 30 30 30 30 30 30 5A 17 0D
32 31 30 32 30 32 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 AE 4C DB 01 F6 14 DE FC 71 21 28 5F DC 7F 5C 6D 1D 42 C9 56
47 F0 61 BA 00 80 DF 67 88 67 84 5E E9 A6 9F D4 89 31 49 DA E3 D3 B1 54
16 D7 53 2C 38 71 52 B8 0B 0D F3 E1 AF 40 8A 95 D3 07 1E 58 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 47 00 30 44 02 20 37 38 73 EF 87 81 B8 82 97 EF 23 5C 1F AC CF 62
DA 4E 44 74 0D C2 A2 E6 A3 C6 C8 82 A3 23 8D 9C 02 20 3A D9 35 3B A7 88
68 3B 06 BB 48 FE CA 16 EA 71 17 17 34 C6 75 C5 33 2B 2A F1 CB 73 38 10
A1 FC
A.1.1. Example CBOR Certificate Compression
The CBOR certificate compression of the X.509 in CBOR diagnostic
format is:
/This defines a CBOR Sequence (RFC 8742):/
1,
h'01f50d',
6,
"RFC test CA",
h'2B044180',
h'2D543300',
h'0123456789AB',
1,
h'02ae4cdb01f614defc7121285fdc7f5c6d1d42c95647f061ba
0080df678867845e',
5,
h'373873EF8781B88297EF235C1FACCF62DA4E44740DC2A2E6A3
C6C882A3238D9C3AD9353BA788683B06BB48FECA16EA711717
34C675C5332B2AF1CB733810A1FC'
The CBOR encoding (CBOR sequence) of the CBOR certificate is 138
bytes.
01 43 01 F5 0D 2A 6B 52 46 43 20 74 65 73 74 20 43 41 44 2B 04 41 80 44
2D 54 33 00 46 01 23 45 67 89 AB 36 58 21 02 AE 4C DB 01 F6 14 DE FC 71
21 28 5F DC 7F 5C 6D 1D 42 C9 56 47 F0 61 BA 00 80 DF 67 88 67 84 5E 05
58 40 37 38 73 EF 87 81 B8 82 97 EF 23 5C 1F AC CF 62 DA 4E 44 74 0D C2
A2 E6 A3 C6 C8 82 A3 23 8D 9C 3A D9 35 3B A7 88 68 3B 06 BB 48 FE CA 16
EA 71 17 17 34 C6 75 C5 33 2B 2A F1 CB 73 38 10 A1 FC
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A.1.2. Example: Natively Signed CBOR Certificate
The corresponding natively signed CBOR certificate in CBOR diagnostic
format is identical except for type and signatureValue.
/This defines a CBOR Sequence (RFC 8742):/
0,
h'01f50d',
6,
"RFC test CA",
h'2B044180',
h'2D543300',
h'0123456789AB',
1,
h'02ae4cdb01f614defc7121285fdc7f5c6d1d42c95647f061
ba0080df678867845e',
5,
h'7F10A063DA8DB2FD49414440CDF85070AC22A266C7F1DFB1
577D9A35A295A8742E794258B76968C097F85542322A0796
0199C13CC0220A9BC729EF2ECA638CFE'
The CBOR encoding (CBOR sequence) of the CBOR certificate is 138
bytes.
00 43 01 F5 0D 2A 6B 52 46 43 20 74 65 73 74 20 43 41 44 2B 04 41 80 44
2D 54 33 00 46 01 23 45 67 89 AB 36 58 21 02 AE 4C DB 01 F6 14 DE FC 71
21 28 5F DC 7F 5C 6D 1D 42 C9 56 47 F0 61 BA 00 80 DF 67 88 67 84 5E 05
58 40 7F 10 A0 63 DA 8D B2 FD 49 41 44 40 CD F8 50 70 AC 22 A2 66 C7 F1
DF B1 57 7D 9A 35 A2 95 A8 74 2E 79 42 58 B7 69 68 C0 97 F8 55 42 32 2A
07 96 01 99 C1 3C C0 22 0A 9B C7 29 EF 2E CA 63 8C FE
A.2. Example HTPPS X.509 Certificate
The DER encoding of the tools.ietf.org 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
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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 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
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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 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.2.1. Example CBOR Certificate Compression
The CBOR certificate compression of the X.509 in CBOR diagnostic
format is:
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/This defines a CBOR Sequence (RFC 8742):/
1,
h'A6A55C870E39B40E',
0,
[
[4, "US"],
[6, "Arizona"],
[5, "Scottsdale"],
[7, "Starfield Technologies, Inc."],
[8, "http://certs.starfieldtech.com/repository/"],
[1, "Starfield Secure Certificate Authority - G2"]
],
h'2D3EE7F6',
h'2F98B716',
[
[8, "Domain Control Validated"],
[-1, "*.tools.ietf.org"]
],
0,
h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
[
-1,
12, [ 1, 2 ],
-4, 5,
17, h'30343032a030a02e862c687474703a2f2f63726c2e737461726669656c64746563682e636f6d2f736669673273312d3234322e63726c',
16, h'305A304E060B6086480186FD6E01071701303F303D06082B060105050702011631687474703A2F2F6365727469666963617465732E737461726669656C64746563682E636F6D2F7265706F7369746F72792F3008060667810C010201',
18, h'3074302A06082B06010505073001861E687474703A2F2F6F6373702E737461726669656C64746563682E636F6D2F304606082B06010505073002863A687474703A2F2F6365727469666963617465732E737461726669656C64746563682E636F6D2F7265706F7369746F72792F73666967322E637274',
14, h'30168014254581685026383D3B2D2CBECD6AD9B63DB36663',
13, [ 1, "*.tools.ietf.org", 1, "tools.ietf.org" ],
15, h'0414AD8AB41C0751D7928907B0B784622F36557A5F4D',
19, h'0481F400F2007700F65C942FD1773022145418083094568EE34D131933BFDF0C2F200BCC4EF164E300000174E5AC711300000403004830460221008CF54852CE5635433911CF10CDB91F52B33639223AD138A41DECA6FEDE1FE90F022100BCA2254366C19A2691C47A00B5B653ABBD44C2F8BAAEF4D2DAF2527CE64549950077005CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA00000174E5AC723C0000040300483046022100A5E0906E63E91D4FDDEFFF0352B91E50896007564B448A3828F596DC6B28726D022100FC91EAED02168866054EE18A2E5346C4CC51FEB3FA10A91D2EDBF99125F86CE6'
],
h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
The CBOR encoding (CBOR sequence) of the CBOR certificate is 1374
bytes.
Appendix B. X.509 Certificate Profile, ASN.1
EDITOR'S NOTE: The ASN.1 below is not up to date with the rest of the
specification. The below ASN.1 for RFC 7925 profile should be in
draft-ietf-uta-tls13-iot-profile instead. If CBOR Certificates
support a large subset of RFC 5280, we should probably not duplicate
all the ASN.1 in that document. Should be discussed what kind and
how much (if any) ASN.1 this document needs. If possible, one option
would be to have ASN.1 for the restrictions compared to RFC 5280.
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Internet-DraftCBOR Encoding of X.509 Certificates (CBOR CerNovember 2020
IOTCertificate DEFINITIONS EXPLICIT TAGS ::= BEGIN
Certificate ::= SEQUENCE {
tbsCertificate TBSCertificate,
signatureAlgorithm AlgorithmIdentifier,
signatureValue BIT STRING
}
TBSCertificate ::= SEQUENCE {
version [0] INTEGER {v3(2)},
serialNumber INTEGER (1..MAX),
signature AlgorithmIdentifier,
issuer Name,
validity Validity,
subject Name,
subjectPublicKeyInfo SubjectPublicKeyInfo,
extensions [3] Extensions OPTIONAL
}
Name ::= SEQUENCE SIZE (1) OF DistinguishedName
DistinguishedName ::= SET SIZE (1) OF CommonName
CommonName ::= SEQUENCE {
type OBJECT IDENTIFIER (id-at-commonName),
value UTF8String
}
Validity ::= SEQUENCE {
notBefore UTCTime,
notAfter UTCTime
}
SubjectPublicKeyInfo ::= SEQUENCE {
algorithm AlgorithmIdentifier,
subjectPublicKey BIT STRING
}
AlgorithmIdentifier ::= SEQUENCE {
algorithm OBJECT IDENTIFIER,
parameters ANY DEFINED BY algorithm OPTIONAL }
}
Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension
Extension ::= SEQUENCE {
extnId OBJECT IDENTIFIER,
critical BOOLEAN DEFAULT FALSE,
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Internet-DraftCBOR Encoding of X.509 Certificates (CBOR CerNovember 2020
extnValue OCTET STRING
}
id-at-commonName OBJECT IDENTIFIER ::=
{joint-iso-itu-t(2) ds(5) attributeType(4) 3}
END
Acknowledgments
The authors want to thank Henk Birkholz, Carsten Bormann, Russ
Housley, Ilari Liusvaara, Laurence Lundblade, Thomas Peterson,
Michael Richardson, Jim Schaad, and Rene Struik for reviewing and
commenting on intermediate versions of the draft.
Authors' Addresses
Shahid Raza
RISE AB
Email: shahid.raza@ri.se
Joel Hoeglund
RISE AB
Email: joel.hoglund@ri.se
Goeran Selander
Ericsson AB
Email: goran.selander@ericsson.com
John Preuss Mattsson
Ericsson AB
Email: john.mattsson@ericsson.com
Martin Furuhed
Nexus Group
Email: martin.furuhed@nexusgroup.com
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