RPKI Signed Object for Trust Anchor Keys
draft-ietf-sidrops-signed-tal-03

Network Working Group                                     T. Bruijnzeels
Internet-Draft                                                NLnet Labs
Intended status: Best Current Practice                       C. Martinez
Expires: December 10, 2018                                        LACNIC
                                                            June 8, 2018


                       RPKI signed object for TAL
                    draft-ietf-sidrops-signed-tal-01

Abstract

   Trust Anchor Locators (TALs) [I-D.ietf-sidrops-https-tal] are used by
   Relying Parties in the RPKI to locate and validate Trust Anchor
   certificates used in RPKI validation.  This document defines an RPKI
   signed object [RFC6488] for a Trust Anchor Locator (TAL) that can be
   used by Trust Anchors to perform a planned migration to a new key,
   allowing Relying Parties to discover the new key up to one year after
   the migration occurred.

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
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   This Internet-Draft will expire on December 10, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Requirements notation . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Signed TAL definition . . . . . . . . . . . . . . . . . . . .   3
     3.1.  The Signed TAL Content Type . . . . . . . . . . . . . . .   4
     3.2.  The Signed TAL eContent . . . . . . . . . . . . . . . . .   4
       3.2.1.  version . . . . . . . . . . . . . . . . . . . . . . .   4
       3.2.2.  activationTime  . . . . . . . . . . . . . . . . . . .   4
       3.2.3.  certificateURIs . . . . . . . . . . . . . . . . . . .   4
       3.2.4.  subjectPublicKeyInfo  . . . . . . . . . . . . . . . .   4
     3.3.  Signed TAL Validation . . . . . . . . . . . . . . . . . .   5
   4.  Signed TAL Generation . . . . . . . . . . . . . . . . . . . .   5
   5.  Signed TAL Publication  . . . . . . . . . . . . . . . . . . .   6
   6.  Performing a planned Key Roll as a Trust Anchor . . . . . . .   6
     6.1.  Prepare a new Trust Anchor key and CA certificate . . . .   7
     6.2.  Publish the new CA certificate  . . . . . . . . . . . . .   7
     6.3.  Verify the validity of the new CA certificate . . . . . .   7
     6.4.  Publish the objects under the current key under the new
           key . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.5.  Verify that the validity of objects under the new key . .   7
     6.6.  Publish a Signed TAL as the only object under the current
           key . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     6.7.  Delete the current key  . . . . . . . . . . . . . . . . .   8
   7.  Relying Party Use . . . . . . . . . . . . . . . . . . . . . .   8
   8.  Deployment Considerations . . . . . . . . . . . . . . . . . .   8
   9.  Unplanned Key Roll operations . . . . . . . . . . . . . . . .   9
   10. Changing a Trust Anchor Certificate URIs  . . . . . . . . . .   9
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
     11.1.  OID  . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     11.2.  File Extension . . . . . . . . . . . . . . . . . . . . .  10
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  10
   13. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     14.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Requirements notation

   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




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   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Introduction

   Trust Anchor Locators (TALs) [I-D.ietf-sidrops-https-tal] are used by
   Relying Parties in the RPKI to locate and validate Trust Anchor
   certificates used in RPKI validation.  This document defines an RPKI
   signed object [RFC6488] for a Trust Anchor Locator (TAL) that can be
   used by Trust Anchors to perform a planned migration to a new key,
   allowing Relying Parties to discover the new key up to one year after
   the migration occurred.  (Note "one year" is arbitrary, and may be
   changed in a future version of this document)

   Note that [RFC5011] describes Automated Updates of DNS Security
   (DNSSEC) Trust Anchors and can provide some useful insight here as
   well.  However, concepts like a set of Trust Anchors, standby Trust
   Anchors, and TTLs are not applicable to the RPKI.  Therefore, an
   alternative approach based on already existing concept of the Trust
   Anchor Locator [I-D.ietf-sidrops-https-tal], and top-down validation
   of an RPKI Trust Anchor certificate tree, where objects are retrieved
   from the RPKI repositories, is appropriate.

3.  Signed TAL definition

   The Signed TAL makes use of the template for RPKI digitally signed
   objects [RFC6488], which defines a Crytopgraphic Message Syntax (CMS)
   [RFC5652] wrapper for the Signed TAL content as well as a generic
   validation procedure for RPKI signed objects.  Therefore, to complete
   the specification of the Signed TAL (see Section 4 of [RFC6488]),
   this document defines:

   o  The OID defined in Section 3.1 that identifies the signed object
      as being a Signed TAL.  (This OID appears within the eContentType
      in the encapContentInfo object as well as the content-type signed
      attribute in the signerInfo object).

   o  The ASN.1 syntax for the Signed TAL eContent defined in
      Section 3.2.  (This is the payload that specifies the AS being
      authorized to originate routes as well as the prefixes to which
      the AS may originate routes.)

   o  Additional steps to the validation steps specified in [RFC6488]
      required to validate Signed TALs, defined in Section 3.3.







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3.1.  The Signed TAL Content Type

   This document requests an OID for signed-Tal as follows:

       signed-Tal OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
                  rsadsi(113549) pkcs(1) pkcs9(9) 16 id-smime (1) TBD }

   This OID MUST appear both within the eContentType in the
   encapContentInfo object as well as the content-type signed attribute
   in the signerInfo object (see [RFC6488])

3.2.  The Signed TAL eContent

   The content of a Signed TAL is ASN.1 encoded using the Distinguished
   Encoding Rules (DER) [X.690], and is defined as follows:

      SignedTAL ::= SEQUENCE {
         version           [0] INTEGER DEFAULT 0,
         activationTime        GeneralizedTime,
         certificateURIs       SEQUENCE SIZE (1..MAX) OF CertificateURI,
         subjectPublicKeyInfo  SubjectPublicKeyInfo }

      CertificateURI ::= IA5String

      SubjectPublicKeyInfo ::= IA5String

3.2.1.  version

   The version number of the SignedTAL MUST be 0.

3.2.2.  activationTime

   This field contains the time when this TAL is intended to replace any
   previously known TAL for this Trust Anchor.

3.2.3.  certificateURIs

   This field is equivalent to the URI section in section 2.1 of
   [I-D.ietf-sidrops-https-tal].  It MUST contain at least one
   CertificateURI element.  Each CertificateURI element contains the
   IA5String representation of either an rsync URI [RFC5781], or an
   HTTPS URI [RFC7230].

3.2.4.  subjectPublicKeyInfo

   This field is equivalent to the subjectPublicKeyInfo section in
   section 2.1 of [I-D.ietf-sidrops-https-tal].




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3.3.  Signed TAL Validation

   To determine whether a Signed TAL is valid, the RP MUST perform the
   following steps in addition to those specified in [RFC6488]:

   o  The eContentType OID matches the OID described in Section 3.1

   o  The Signed TAL appears as the product of a Trust Anchor CA
      certificate.

   o  This Trust Anchor CA has published only one Signed TAL object in
      its repository, and this object appears on the Manifest as the
      only entry using the ".tal" extension (see [RFC6481]).  In case
      more than one Signed TAL object is found, all such objects MUST be
      considered invalid.

   o  The EE certificate of this Signed TAL describes its Internet
      Number Resources (INRs) using the "inherit" attribute

   o  The decoded TAL content conforms to the format defined in
      Section 3.2.

   If the above procedure indicates that the manifest is invalid, then
   the Signed TAL MUST be discarded and treated as though no Signed TAL
   were present.

4.  Signed TAL Generation

   A TA MAY choose to generate a single Singed TAL object to publish in
   its TA certificate publication point(s) in the RPKI.  The TA MUST
   perform the following steps to generate the Signed TAL:

   o  Generate a key pair for a "one-time-use" EE certificate to use for
      the Signed TAL

   o  Generate a one-time-use EE certificate for the Signed TAL

   o  This EE certificate MUST have an SIA extension access description
      field with an accessMethod OID value of id-ad-signedobject, where
      the associated accessLocation references the publication point of
      the Sigend TAL as an object URL.

   o  As described in [RFC6487], an [RFC3779] extension is required in
      the EE certificate used for this object.  However, because the
      resource set is irrelevant to this object type, this certificate
      MUST describe its Internet Number Resources (INRs) using the
      "inherit" attribute, rather than explicit description of a
      resource set.



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   o  This EE certificate MUST have a "notBefore" time that is before
      the moment that the Signed TAL will be published.

   o  This EE certificate MUST have a "notAfter" time that reflects the
      intended time that this Signed TAL will be published.  If the EE
      certificate for a Signed TAL is expired, it MUST no longer be
      publish, but of course it MAY be replaced by a newly generated
      Signed TAL object with similar content and an updated "notAfter"
      time.

   o  The Signed TAL MUST have an "activationTime" that reflects when
      Relying Parties MUST use use this new TAL in place of any
      previously known TAL for this Trust Anchor.

5.  Signed TAL Publication

   A TA MAY publish a single Signed TAL object directly under its CA
   repository publication points.  The TA MUST NOT publish multiple
   Signed TAL objects at any time.  It is RECOMMENDED that a TA
   publishes a Signed TAL object for its current key and CA certificate
   publication URIs at all times.

   A non-normative guideline for naming this object is that the filename
   chosen for the signed TAL in the publication repository be a value
   derived from the public key part of the entity's key pair, using the
   algorithm described for CRLs in section 2.2 of [RFC6481] for
   generation of filenames.  The filename extension of ".tal" MUST be
   used to denote the object as a signed TAL.  Note that this is in-line
   with filename extensions defined in section 7.2 of [RFC6481]

6.  Performing a planned Key Roll as a Trust Anchor

   A Signed TAL SHOULD be used to communicate a planned key roll by a
   Trust Anchor.  From the Trust Anchor perspective a planned key roll
   consists of the following steps:

   o  Prepare a new Trust Anchor key and CA certificate, see Section 6.1

   o  Publish the new CA certificate, see Section 6.2

   o  Verify the validity of the new CA certificate, see Section 6.3

   o  Publish the objects under the current key under the new key, see
      Section 6.4

   o  Verify that the validity of objects under the new key, see
      Section 6.5




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   o  Publish a Signed TAL as the only object under the current key, see
      Section 6.6

   o  Delete the current key, see Section 6.7

6.1.  Prepare a new Trust Anchor key and CA certificate

   The Trust Anchors MUST a new key pair and generate a new TA
   Certificate.  For the Subject Information Access (see section 4.8.8.1
   of [RFC6487]) this MUST use URIs that will be used by the new key to
   publish objects.  These URIs MUST be uniqe for use by this new key
   only.  The Internet Number Resources on this new certificate MUST be
   equivalent to those found on the current certificate.

6.2.  Publish the new CA certificate

   The new CA certificate MUST be published under one or more new
   Certificate URIs for use by this new key only.

6.3.  Verify the validity of the new CA certificate

   The Trust Anchor MUST generate a new (unsigned) TAL file
   [I-D.ietf-sidrops-https-tal] and verify with RP software that the new
   Trust Anchor certificate can be retrieved from all locations and that
   it matches the subjectPublicKeyInfo

6.4.  Publish the objects under the current key under the new key

   ALL current signed certificates and other objects, with the exception
   of the CRL, Manifest and existing Signed TAL, must be re-issued by
   the new key and published under the new publication point(s).

   It is RECOMMENDED that a new Signed TAL object is generated and
   published, listing the Certificate URIs for this new key, the
   subjectPublicKeyInfo of this new key, and using an "activationTime"
   that is effective immediately.  Note that Relying Parties will not
   discover this new Signed TAL object until they have effectively
   switched over from the current key.

6.5.  Verify that the validity of objects under the new key

   The Trust Anchor MUST verify that validation using the new TAL file
   generated in Section 6.3 results in the set of valid objects as when
   the current TAL file is used.







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6.6.  Publish a Signed TAL as the only object under the current key

   The Trust Anchor MUST publish a new Signed TAL, CRL and Manifest as
   the only objects under the current, to be deleted, key.  The
   "nextUpdate" values of the Manifest and CRL objects SHOULD use a date
   that is set at least one year into the future. (arbitrary value, open
   to suggestions).  The "notValidAfter" date on the Manifest and Signed
   TAL EE certificate SHOULD use this same date.  The Trust Anchor MUST
   ensure that this Signed TAL, CRL and Manifest remain available for
   download for this full period.  Note that this is done to give RPs
   the opportunity to discover the new key up to one year after the key
   roll occurred.

6.7.  Delete the current key

   As the final step the current key, which has been replaced now,
   SHOULD be deleted.  The new key can now be marked as the current key.

7.  Relying Party Use

   When an RP discovers a valid Signed TAL signed under a TA, and it
   notices that the "subjectPublicKeyInfo" has changed and/or the set of
   "Certificate URIs" has changed from the values it knew for this TA,
   and the "activationTime" is in the past, then the RP MUST accept
   these new values for this TA, abort the current top-down validation
   operation, and initiate a new top-down validation operation using the
   updated information.

   Note that the Trust Anchor MUST have verified that all objects are
   available under the new key (Section 6.5) and that that the TA CA
   certificate can be retrieved and validated for all new URIs
   (Section 6.3).

8.  Deployment Considerations

   Including Signed TAL objects while RP tools do not support this
   standard will result in these RPs rejecting these objects.  It is not
   expected that this will result in the invalidation of any other
   object under a Trust Anchor.

   That said, the flagging mechanism introduced here can only be trusted
   on once a majority of RPs support it.  Defining when that moment
   arrives is by definition something that cannot be established at the
   time of writing this document.

   However, once the majority of RPs support this mechanism it would be
   RECOMMENDED that Trust Anchor operators perform key rolls regularly.




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   The most assured way to know that such planned rolls will work is by
   making them a part of normal operations.

9.  Unplanned Key Roll operations

   The mechanism described in this document is not applicable to
   uplanned key rolls.  Unplanned key rolls could theoretically be
   supported by a mechanism where a new key is introduced before it's
   used, with the power to revoke the current key.  This would have to
   be signalled from the new key, as the TA may have lost access to its
   current key.

   However, this introduces a great amount of operational complexity as
   well as a new vulnerability: an adversary would need access to only
   one of these keys in order to compromise a TA.

   With that in mind we believe, for now, that unplanned key rolls
   should not be covered here, and would need to be communicated to
   Relying Parties in some other out-of-band fashion.

10.  Changing a Trust Anchor Certificate URIs

   Earlier versions of this document included a description of how
   Signed TAL objects could be used to signal a change of Certificate
   URIs only; i.e. where the key is not changed.

   However, Relying Parties that do not support the mechanism described
   in this document would not be able to learn about the changes in
   URIs.  While for RPs that do support this mechanism a planned key
   roll will be a normal part of RPKI validation.

   Therefore we believe that a planned key roll should be used in cases
   like this, and that the set of Certificate URIs for any given key
   must never be changed.

11.  IANA Considerations

11.1.  OID

   IANA is to add the following to the "RPKI Signed Objects" registry:

          Decimal | Description                    | References
          --------+--------------------------------+---------------
          TBD     | signed-Tal                     | [section 3.1]







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11.2.  File Extension

   IANA is to add an item for the Signed TAL file extension to the "RPKI
   Repository Name Scheme" created by [RFC6481] as follows:

          Extension  |   RPKI Object              | References
          -----------+-------------------------------------------
           .tal      |   Signed TAL               | [this document]

12.  Security Considerations

   TBD

13.  Acknowledgements

   TBD

14.  References

14.1.  Normative References

   [I-D.ietf-sidrops-https-tal]
              Huston, G., Weiler, S., Michaelson, G., Kent, S., and T.
              Bruijnzeels, "Resource Public Key Infrastructure (RPKI)
              Trust Anchor Locator", draft-ietf-sidrops-https-tal-03
              (work in progress), June 2018.

   [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>.

   [RFC3779]  Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
              Addresses and AS Identifiers", RFC 3779,
              DOI 10.17487/RFC3779, June 2004,
              <https://www.rfc-editor.org/info/rfc3779>.

   [RFC5011]  StJohns, M., "Automated Updates of DNS Security (DNSSEC)
              Trust Anchors", STD 74, RFC 5011, DOI 10.17487/RFC5011,
              September 2007, <https://www.rfc-editor.org/info/rfc5011>.

   [RFC5781]  Weiler, S., Ward, D., and R. Housley, "The rsync URI
              Scheme", RFC 5781, DOI 10.17487/RFC5781, February 2010,
              <https://www.rfc-editor.org/info/rfc5781>.







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   [RFC6481]  Huston, G., Loomans, R., and G. Michaelson, "A Profile for
              Resource Certificate Repository Structure", RFC 6481,
              DOI 10.17487/RFC6481, February 2012,
              <https://www.rfc-editor.org/info/rfc6481>.

   [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>.

   [RFC6488]  Lepinski, M., Chi, A., and S. Kent, "Signed Object
              Template for the Resource Public Key Infrastructure
              (RPKI)", RFC 6488, DOI 10.17487/RFC6488, February 2012,
              <https://www.rfc-editor.org/info/rfc6488>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,
              <https://www.rfc-editor.org/info/rfc7230>.

   [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>.

   [X.690]    ITU-T Recommendation X.690 (2002) | ISO/IEC 8825-1:2002,
              "Information technology - ASN.1 encoding rules:
              Specification of Basic Encoding Rules (BER), Canonical
              Encoding Rules (CER) and Distinguished Encoding Rules
              (DER)", 2002.

14.2.  Informative References

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, DOI 10.17487/RFC5652, September 2009,
              <https://www.rfc-editor.org/info/rfc5652>.

Authors' Addresses

   Tim Bruijnzeels
   NLnet Labs

   Email: tim@nlnetlabs.nl
   URI:   https://www.nlnetlabs.nl/








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   Carlos Martinez
   LACNIC

   Email: carlos@lacnic.net
   URI:   https://www.lacnic.net/














































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