Using SM2 with JOSE and COSE
draft-dang-webauthn-sm2-00

Document Type Active Internet-Draft (individual)
Author Fan Dang 
Last updated 2021-11-06
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WebAuthn Working Group                                           F. Dang
Internet-Draft                                       Tsinghua University
Intended status: Informational                           6 November 2021
Expires: 10 May 2022

                      Using SM2 with JOSE and COSE
                       draft-dang-webauthn-sm2-00

Abstract

   This specification defines algorithm encodings and representations
   enabling the ISO/IEC 14888-3:2018 elliptic curve "SM2" to be used for
   JSON Object Signing and Encryption (JOSE) and CBOR Object Signing and
   Encryption (COSE) messages.

Status of This Memo

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

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   This Internet-Draft will expire on 10 May 2022.

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   provided without warranty as described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Notation and Conventions . . . . . . . . . .   2
   2.  JOSE and COSE SM2 Curve Key Representations . . . . . . . . .   2
   3.  ECDSA Signature with SM2 Curve  . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  JSON Web Key Elliptic Curve Registration  . . . . . . . .   3
     4.2.  JOSE Algorithm Registration . . . . . . . . . . . . . . .   3
     4.3.  COSE Elliptic Curves Registration . . . . . . . . . . . .   4
     4.4.  COSE Algorithm Registration . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Document History . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   This specification defines algorithm encodings and representations
   enabling the ISO/IEC 14888-3:2018 elliptic curve "SM2" [ISO14888-3]
   to be used for JSON Object Signing and Encryption (JOSE) [RFC7515]
   and CBOR Object Signing and Encryption (COSE) [RFC8152] messages.
   The elliptic curve and associated algorithm are registered in
   appropriate IANA JOSE and COSE registries.

1.1.  Requirements Notation and 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.

2.  JOSE and COSE SM2 Curve Key Representations

   The ISO/IEC 14888-3:2018 elliptic curve "SM2" [ISO14888-3] is
   represented in a JSON Web Key (JWK) [RFC7517] using these values:

   *  kty: EC
   *  crv: SM2

   plus x and y values to represent the curve point for the key.  Other
   optional values such as alg MAY also be present.

   It is represented in a COSE_Key [RFC8152] using these values:

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   *  kty (1): EC2 (2)
   *  crv (-1): SM2 (TBD - requested assignment 9)

   plus x (-2) and y (-3) values to represent the curve point for the
   key.  Other optional values such as alg (3) MAY also be present.

3.  ECDSA Signature with SM2 Curve

   The ECDSA signature algorithm is defined in [ISO14888-3].
   Implementations need to check that the key type is EC for JOSE or EC2
   (2) for COSE when creating or verifying a signature.

   The ECDSA algorithm specified in this document is:

     +===============+================================+=============+
     | JOSE Alg Name | COSE Alg Value                 | Description |
     +===============+================================+=============+
     | SM2           | TBD (requested assignment -48) | ECDSA w/    |
     |               |                                | SM2 Curve   |
     +---------------+--------------------------------+-------------+

                     Table 1: ECDSA Algorithm Values

4.  IANA Considerations

4.1.  JSON Web Key Elliptic Curve Registration

   This section registers the following value in the IANA "JSON Web Key
   Elliptic Curve" registry [IANA.JOSE.Curves].

   *  Curve Name: curveSM2
   *  Curve Description: SM2 Curve
   *  JOSE Implementation Requirements: Optional
   *  Change Controller: IESG
   *  Specification Document(s): Section 2 of [[ this specification ]]

4.2.  JOSE Algorithm Registration

   This section registers the following value in the IANA "JSON Web
   Signature and Encryption Algorithms" registry [IANA.JOSE.Algorithms].

   *  Algorithm Name: SM2
   *  Algorithm Description: ECDSA w/ SM2 Curve
   *  Algorithm Usage Locations: alg
   *  JOSE Implementation Requirements: Optional
   *  Change Controller: IESG
   *  Reference: Section 3 of [[ this specification ]]
   *  Algorithm Analysis Document(s): [ISO14888-3]

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4.3.  COSE Elliptic Curves Registration

   This section registers the following value in the IANA "COSE Elliptic
   Curves" registry [IANA.COSE.Curves].

   *  Name: curveSM2
   *  Value: TBD (requested assignment 9)
   *  Key Type: EC2
   *  Description: SM2 Curve
   *  Change Controller: IESG
   *  Reference: Section 2 of [[ this specification ]]
   *  Recommended: Yes

4.4.  COSE Algorithm Registration

   This section registers the following value in the IANA "COSE
   Algorithms" registry [IANA.COSE.Algorithms].

   *  Name: SM2
   *  Value: TBD (requested assignment -48)
   *  Description: ECDSA w/ SM2 Curve
   *  Reference: Section 3 of this document
   *  Recommended: Yes

5.  Security Considerations

   The procedures and security considerations described in the
   [ISO14888-3] specifications apply to implementations of this
   specification.

6.  References

6.1.  Normative References

   [ISO14888-3]
              International Organization for Standardization, "IT
              Security techniques - Digital signatures with appendix -
              Part 3: Discrete logarithm based mechanisms", November
              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>.

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <https://www.rfc-editor.org/info/rfc7515>.

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   [RFC7517]  Jones, M., "JSON Web Key (JWK)", RFC 7517,
              DOI 10.17487/RFC7517, May 2015,
              <https://www.rfc-editor.org/info/rfc7517>.

   [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>.

6.2.  Informative References

   [IANA.COSE.Algorithms]
              IANA, "COSE Algorithms",
              <https://www.iana.org/assignments/cose/
              cose.xhtml#algorithms>.

   [IANA.COSE.Curves]
              IANA, "COSE Elliptic Curves",
              <https://www.iana.org/assignments/cose/
              cose.xhtml#elliptic-curves>.

   [IANA.JOSE.Algorithms]
              IANA, "JSON Web Signature and Encryption Algorithms",
              <https://www.iana.org/assignments/jose/jose.xhtml#web-
              signature-encryption-algorithms>.

   [IANA.JOSE.Curves]
              IANA, "JSON Web Key Elliptic Curve",
              <https://www.iana.org/assignments/jose/jose.xhtml#web-key-
              elliptic-curve>.

Appendix A.  Document History

   [[ to be removed by the RFC Editor before publication as an RFC ]]

   -00

   *  Initial version.

Author's Address

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   Fan Dang
   Tsinghua University
   Beijing
   100084
   China

   Email: dangfan@tsinghua.edu.cn

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