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Versions: 00 01                                                         
Workgroup:          Network Working Group                      C. Zhang
Internet-Draft:     draft-cuiling-dnsop-sm2-alg-00               Y. Liu
Updates:            8624 (if approved)                          F. Leng
Published:          2022-04-07                                  Q. Zhao
Intended Status:    Informational                                 Z. He
Expires:            2022-10-07                                    CNNIC



SM2 Digital Signature Algorithm for DNSSEC

Abstract

  This document describes how to specify SM2 Digital Signature
  Algorithm keys and signatures in DNS Security (DNSSEC). It lists
  the curve and uses SM3 as hash algorithm for signatures.

Status of This Memo

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  provisions of BCP 78 and BCP 79.

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  This Internet-Draft will expire on xx xxx 2022.

Copyright Notice

  Copyright (c) 2022 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
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  described in the Revised BSD License.

1.  Introduction

  DNSSEC is broadly defined in RFCs 4033, 4034, and 4035 ([RFC4033],
  [RFC4034], and [RFC4035]). It uses cryptographic keys and digital
  signatures to provide authentication of DNS data. Currently, there
  are several signature algorithms, such as RSA with SHA-256,ECDSA
  with curve P-256 and SHA-256, etc.

  This document defines the DNSKEY and RRSIG resource records (RRs)
  of a new signing algorithms: SM2 uses elliptic curves over 256-bit
  prime fields with SM3 hash algorithm. (A description of SM2 and SM3
  can be found in ISO/IEC 10118-3:2018 [ISO/IEC10118-3:2018] and
  ISO/IEC 14888-3:2018 [ISO/IEC14888-3:2018].) This document also
  defines the DS RR for the SM3 one-way hash algorithm. In the signing
  algorithm defined in this document, the size of the key for the
  elliptic curve is matched with the size of the output of the hash
  algorithm. Both are 256 bits.

  Like all ECC-based algorithms, signing with SM2 is significantly
  faster than RSA based algorithms, while the validating is slower.

  Due to the similarity between SM2 and ECDSA with curve P-256, some
  of the material in this document is copied liberally from RFC 6605
  [RFC6605].

  The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
  "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
  document are to be interpreted as described in RFC 2119 [RFC2119].

2.  SM3 DS Records

  SM3 is included in ISO/IEC 10118-3:2018 and is similar to SHA-256
  in many ways. The implementation of SM3 in DNSSEC follows the
  implementation of SHA-256 as specified in RFC 4509[RFC4509] except
  that the underlying algorithm is SM3, the digest value is 32 bytes
  long, and the digest type code is 17 [to be determined].

3.  SM2 Parameters

  Verifying SM2 signatures requires agreement between the signer and
  the verifier of the parameters used. SM2 digital signature algorithm
  has been added to ISO/IEC 14888-3:2018. And the parameters of the
  curve used in this document are as follows:

p  = FFFFFFFE FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 00000000 FFFFFFFF FFFFFFFF
a  = FFFFFFFE FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 00000000 FFFFFFFF FFFFFFFC
b  = 28E9FA9E 9D9F5E34 4D5A9E4B CF6509A7 F39789F5 15AB8F92 DDBCBD41 4D940E93
xG = 32C4AE2C 1F198119 5F990446 6A39C994 8FE30BBF F2660BE1 715A4589 334C74C7
yG = BC3736A2 F4F6779C 59BDCEE3 6B692153 D0A9877C C62A4740 02DF32E5 2139F0A0
n  = FFFFFFFE FFFFFFFF FFFFFFFF FFFFFFFF 7203DF6B 21C6052B 53BBF409 39D54123

4.  DNSKEY and RRSIG Resource Records for SM2

  SM2 public keys consist of a single value, called "P". In DNSSEC keys,
  P is   a simple bit string that represents the uncompressed form of a
  curve point, "x | y".

  The SM2 signature is the combination of two non-negative integers,
  called "r" and "s". The two integers, each of which is formatted as
  a simple octet string, are combined into a single longer octet string
  for DNSSEC as the concatenation "r | s". (Conversion of the integers
  to bit strings is the same as ECDSA signature.) Each integer MUST be
  encoded as 32 octets.

  Although SM2 uses elliptic curves, the process of digest and signature
  generation is different from ECDSA.

  The algorithm number associated with the DNSKEY and RRSIG resource records
  is fully defined in the IANA Considerations section. It is:

  DNSKEY and RRSIG RRs signifying SM2 with SM3 use the algorithm number 17
  [to be determined].

  Conformant implementations that create records to be put into the DNS MAY
  implement signing and verification for the above algorithm. Conformant
  DNSSEC verifiers MAY implement verification for the above algorithm.

5.  Support for NSEC3 Denial of Existence

  This document does not define algorithm aliases mentioned in RFC 5155
  [RFC5155].

  A DNSSEC validator that implements the signing algorithms defined in this
  document MUST be able to validate negative answers in the form of both NSEC
  and NSEC3 with hash algorithm 1, as defined in RFC 5155. An authoritative
  server that does not implement NSEC3 MAY still serve zones that use the
  signing algorithms defined in this document with NSEC denial of existence.

6.  Example

  The following is an example of SM2 keys and signatures in DNS format.

6.1. SM2 Example

  Private-key-format: v1.3
  Algorithm: 17[to be determined] (SM2SM3)
  PrivateKey: V24tjJgXxp2ykscKRZdT+iuR5J1xRQN+FKoQACmo9fA=

  example.net. 3600 IN DNSKEY 257 3 17 (
    jZbZMBImG9dtGWSVEwnv2l32OVKcX7MMJv+83/+A41ia
    ZuO0ajXMcuyJbTr8Ud+kae6UlfqrnsG6tgADIPHxXA== )

  example.net. 3600 IN DS 27215 17 6 (
    86671f82dd872e4ee73647a95dff7fd0af599ff8a43f
    fa26c9a2593091653c0e )

  www.example.net. 3600 IN A 192.0.2.1
  www.example.net. 3600 IN RRSIG A 17 6 3600 (
    20220428075649 20220331075649 27215 example.net.
    tz295lkfu2InRnLdLhKWDm354I6ZGSmYeOSDswKiQMU7
    /Va0QrH7bD7ZnHB4wWsEjfy1XscwM4P86sVxkMJE7w== )


7.  IANA Considerations

  This document updates the IANA registry for digest types in DS records,
  currently called "Delegation Signer (DS) Resource Record (RR) Type Digest
  Algorithms".  The following entry has been added:

       Value          6 [to be determined]
       Digest Type    SM3
       Status         OPTIONAL

  This document updates the IANA registry "Domain Name System Security
  (DNSSEC) Algorithm Numbers".  The following two entries have been added
  to the registry:

       Number         17
       Description    SM2 signing algorithm with SM3 hashing algorithm
       Mnemonic       SM2SM3
       Zone Signing   Y
       Trans. Sec.    *
       Reference      This document


  * There has been no determination of standardization of the use of this
  algorithm with Transaction Security.

8.  Security Considerations

  The cryptographic work factor of SM2 is generally considered to be
  equivalent to half the size of the key, which is 128 bits. Such an
  assessment could, of course, change in the future if new attacks that
  work better than the ones known today are found.

  SM2 digital signature algorithm has come into use for less than a score
  of years. So SM2SM3 algorithm is mainly used for research and experiment
  purpose currently.

  The security considerations listed in RFC 4509 apply here as well.

9.  Normative References

  [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

  [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
             Rose, "DNS Security Introduction and Requirements",
               RFC 4033, March 2005.

  [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
             Rose, "Resource Records for the DNS Security
             Extensions", RFC 4034, March 2005.

  [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
             Rose, "Protocol Modifications for the DNS Security
             Extensions", RFC 4035, March 2005.

  [RFC4509]  Hardaker, W., "Use of SHA-256 in DNSSEC Delegation
             Signer (DS) Resource Records (RRs)", RFC 4509,
             May 2006.

  [RFC5155]  Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
             Security (DNSSEC) Hashed Authenticated Denial of
             Existence", RFC 5155, March 2008.

  [RFC6605]  Hoffman, P., and Wouter C.A. Wijngaards, "Elliptic Curve
             Digital Signature Algorithm (DSA) for DNSSEC", RFC 6605,
             April 2012.

  [ISO/IEC14888-3:2018]  International Organization for Standardization,
             "IT Security techniques -- Digital signatures with appendix
              -- Part 3: Discrete logarithm based mechanisms", ISO ISO/IEC
              14888-3:2018, November 2018.

  [ISO/IEC10118-3:2018]  International Organization for Standardization,
             "IT Security techniques -- Hash-functions -- Part 3: Dedicated
             hash-functions", ISO ISO/IEC 10118-3:2018, October 2018.

Authors' Addresses

   Cuiling Zhang
   CNNIC
   No.4 South 4th Street, Zhongguancun
   Beijing, 100190
   China

   Email: zhangcuiling@cnnic.cn

   Yukun Liu
   CNNIC
   No.4 South 4th Street, Zhongguancun
   Beijing, 100190
   China

   Email: liuyukun@cnnic.cn

   Feng Leng
   CNNIC
   No.4 South 4th Street, Zhongguancun
   Beijing, 100190
   China

   Email: lengfeng@cnnic.cn

   Qi Zhao
   CNNIC
   No.4 South 4th Street, Zhongguancun
   Beijing, 100190
   China

   Email: zhaoqi@cnnic.cn

   Zheng He
   CNNIC
   No.4 South 4th Street, Zhongguancun
   Beijing, 100190
   China

   Email: hezh@cnnic.cn