Workgroup: Network Working Group C. Zhang Internet-Draft: draft-cuiling-dnsop-sm2-alg-02 Y. Liu Updates: 8624 (if approved) F. Leng Published: 2023-01-05 Q. Zhao Intended Status: Informational Z. He Expires: 2023-06-16 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 This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on xx xxx 2023. 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 Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as 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 GBT.32918.2-2016 [GBT.32918.2-2016] 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 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 [to be determined] 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 of ECC-based algorithms is influenced by the curve it uses. SM2 uses a different curve and has different process with the signature generation and validation, so SM2 could be considered as an alternative to ECDSA. The security considerations listed in RFC 4509 apply here as well. 9. References 9.1. 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. 9.2. Informative References [GBT.32918.2-2016] Standardization Administration of the People's Republic of China, "Information security technology --- Public key cryptographic algorithm SM2 based on elliptic curves --- Part 2: Digital signature algorithm", GB/T 32918.2-2016, March 2017, <http://www.gmbz.org.cn/ upload/2018-07-24/1532401673138056311.pdf>. [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. Appendix A. Example Zone This is a zone showing its RRSIG RRs generated with SM3 hash algorithm and SM2 signature algorithm. example. 3600 IN SOA ns1.example. root.example. ( 1 ; serial 3600 ; refresh (1 hour) 300 ; retry (5 minutes) 3600000 ; expire (5 weeks 6 days 16 hours) 3600 ; minimum (1 hour) ) RRSIG SOA 17 1 3600 ( 20230901000000 20220901000000 65042 example. vXGQ/M+QJbEzdF9MW8rqJVN+QC5LdpK7k7vt nupu/SrZhiKDGcXpORMpprlljlQ6w4YqytdA ZHfbu25HfIyEgw== ) NS ns1.example. NS ns2.example. RRSIG NS 17 1 3600 ( 20230901000000 20220901000000 65042 example. xXR6eAWSdv9KpEtX/GccI0AFafmUoARf9Q1i CgtoJKjFCQySqBLVxlgiQQaTpZqY8taepygv 8g5o5mHsfmyPiw== ) DNSKEY 256 3 17 ( 7EQ32PTAp+1ac6R9Ze2nfB8pPc2OJqkHSjug ALr4SuD9awuQxhfw7wMpiXv7JK4/VwwTrCxJ wu+qUuDsgoBK4w== ) ; ZSK; alg = SM2SM3 ; key id = 65042 DNSKEY 257 3 17 ( jZbZMBImG9dtGWSVEwnv2l32OVKcX7MMJv+8 3/+A41iaZuO0ajXMcuyJbTr8Ud+kae6Ulfqr nsG6tgADIPHxXA== ) ; KSK; alg = SM2SM3 ; key id = 27215 RRSIG DNSKEY 17 1 3600 ( 20230901000000 20220901000000 65042 example. lF2eq49e62Nn4aT5x8ZI6PdRSTPHPDixZdyl lM6GWu4lkRWkpTgWLE4lQK/+qHdNS4DdTd36 Jsuu0FSO5k48Qg== ) RRSIG DNSKEY 17 1 3600 ( 20230901000000 20220901000000 27215 example. +MDF1bnH/8zCeOwJQbWSfwb6OCB8fp16rxog S9+PbxHEcKNTOUX3hPxdM8NblDgY19c+KDmr xei2D84M2B50cQ== ) 0 NSEC3PARAM 1 0 10 AABBCCDD 0 RRSIG NSEC3PARAM 17 1 0 ( 20230901000000 20220901000000 65042 example. aqntwEYEJzkVb8SNuJLwdx7f+vivv5IUIeAj 6/TGt2/bewiM/Hp9fqOysEcjgWZ7lZbqJsR5 HtKlddixnjmOFQ== ) ns2.example. A 192.0.2.2 RRSIG A 17 2 3600 ( 20230901000000 20220901000000 65042 example. xqot4urj885t1SDnAZnozl4s3t/El1HZVLwb 0N2Bb6IdEBtH/SNJdN1Zz/xBysCGkRwoMq2I Uk+v3Yl6Uo8Eiw== ) ns1.example. A 192.0.2.1 RRSIG A 17 2 3600 ( 20230901000000 20220901000000 65042 example. 5ZNwC4No82PeHZd5PgdGmBsvRxjBe3FlnA4S g8/tDZlHM7QSbDDN17r8+qHq+AeXKy8cSF3n U+byf9VjzV9IKA== ) www.example. A 192.0.2.3 RRSIG A 17 2 3600 ( 20230901000000 20220901000000 65042 example. vNTwnIQzImSG6b6F0dNhNz+mt8oSRITzfiNh mzdvI0w1eHxTetA/3Tu3HLoDYDw+D5uGcoVZ NlvZpyrIU1BIAA== ) S0OCR8EH8COF31Q1TO66KIDIT4A4RV8R.example. NSEC3 1 1 10 AABBCCDD ( 62KP1QB93KRGR6LM7SEVPJVNG90BLUE8 A RRSIG ) RRSIG NSEC3 17 2 3600 ( 20230901000000 20220901000000 65042 example. ai3O/vkgVX6DRJFjfwWJI71QNXucCaTpWBAQ JyedgjRGC/XgX1WF60SglDzWmlHdyACPHV4S 1dBE344tnNgAtA== ) GTGVQIILTSSJ8FFO9J6DC8PRTFAEA8G2.example. NSEC3 1 1 10 AABBCCDD ( NIU1DMQS67H1PIN9JIMC33JCMO8MU99T A RRSIG ) RRSIG NSEC3 17 2 3600 ( 20230901000000 20220901000000 65042 example. 3BUwHiacqHADK7Y31kFa4JnGOrURCXlZNmZq B163jles9HCQHIDR60DFZdZhx1sVBsd8Rl+L dUcia3aUgNqwlA== ) NIU1DMQS67H1PIN9JIMC33JCMO8MU99T.example. NSEC3 1 1 10 AABBCCDD ( OHVFQ9KQA23B5PM64EST8LNRQRLQ624H A RRSIG ) RRSIG NSEC3 17 2 3600 ( 20230901000000 20220901000000 65042 example. ctAutz6smtvUeeCyZPel3BTYJzkJcYGXEDRH hosBrWRiipM/C94nZxFpYioK+mq5tw9yebwH 83Vq94AChHbabg== ) test.example. A 192.0.2.4 RRSIG A 17 2 3600 ( 20230901000000 20220901000000 65042 example. H9+NQdd9o4NTj8siRO8c5IrjJ/6BuNaZdgeh AbcwTcxBvhE7D4XeHH9zUcZ0gVuhdR8WoA8H FVbCrekKGgW7Gw== ) OHVFQ9KQA23B5PM64EST8LNRQRLQ624H.example. NSEC3 1 1 10 AABBCCDD ( S0OCR8EH8COF31Q1TO66KIDIT4A4RV8R A RRSIG ) RRSIG NSEC3 17 2 3600 ( 20230901000000 20220901000000 65042 example. eygDRIjsL+OXE4leoBuZOFptq+FMkWGfXA19 ojaJlnRfeLXEHKBrCFMEe+8l3qlTkGFsBo3N E3tQU4uSMafViA== ) 62KP1QB93KRGR6LM7SEVPJVNG90BLUE8.example. NSEC3 1 1 10 AABBCCDD ( GTGVQIILTSSJ8FFO9J6DC8PRTFAEA8G2 NS SOA RRSIG DNSKEY NSEC3PARAM ) RRSIG NSEC3 17 2 3600 ( 20230901000000 20220901000000 65042 example. FOWLegTgFkFY9vCOo4kHwjEvZ+IL1NMl4s9V hVyPOwokd5uOLKeXTP19HIeEtW73WcJ9XNe/ ie/knp7Edo/hxw== ) 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