Internet Engineering Task Force Y. Liu
Internet Draft Z. Li
Intended status: Experimental J. Chen
Expires: May 8 2025 X. Fan
China Academy of Information and Communications Technology
November 8, 2024
ShangMi(SM) Cipher for OpenPGP
draft-liu-sm-for-openpgp-01
AbstractThis document introduces the Shang Mi(SM) cryptographic algorithm for openpgp protocol.
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Table of Contents1. Introduction...................................................2
1.1. The SM Algorithms.........................................2
1.2. Terminology...............................................3
2. Supported Public Key Algorithm: SM2............................3
2.1. Point Format..............................................3
2.2. Curve OID.................................................3
2.3. Key Algorithms id.........................................3
3. Supported Symmetric-Key Algorithm: SM4.........................4
4. Supported Hash Algorithm: SM3..................................4
4.1. Algorithm ID..............................................4
4.2. Hash OID..................................................5
5. IANA Considerations............................................5
6. Security Considerations........................................5
7. References.....................................................5
7.1. Normative References......................................5
7.2. Informative References....................................6
8. Acknowledgments................................................7
1. Introduction
The OpenPGP specification in [RFC4880] defines the RSA, Elgamal, and DSA public key algorithms. [RFC6637] adds support for Elliptic Curve Cryptography and specifies the ECDSA and ECDH algorithms.This document specifies how to use the SM cryptographic algorithms with the OpenPGP standard. The SM algorithm is a highly recommended algorithm in China and has become an ISO/IEC international standard.This document provides a description of how to use them in OpenPGP.
1.1. The SM Algorithms
This document describes several different SMs cryptographic algorithms, including SM2 for authentication, SM4 for encryption, and SM3 as the hash function.SM2 is a suite of cryptographic algorithms based on elliptic curve cryptography, including a digital signature, public key encryption and key exchange scheme. This document only deals with the SM2 digital signature algorithm and public key encryption algorithm
that have been added to ISO/IEC 14888-3:2018 [ISO- SM2] add [GBT.32918.2-2016]). SM4 is a block cipher algorithm defined in [GBT.32907-2016] and now is being standardized by ISO toISO/IEC 18033-3:2010 [ISO-SM4]. SM3 is a hash function that outputs
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Internet-Draft ShangMi(SM) Cipher for OpenPGP November 2024 256 bits. SM3 has already listed in ISO/IEC 10118-3:2018 [ISO- SM3] and has also been described by [GBT.32905-2016]. 1.2. TerminologyThe 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. Supported Public Key Algorithm: SM2 2.1. Point FormatThis document only defines the uncompressed point format. The point is encoded in the Multiprecision Integer (MPI) format [RFC4880]. The content of the MPI is the following:
B = 04 || x || y
where x and y are coordinates of the point P = (x, y), each encoded in the big-endian format and zero-padded to the adjusted underlying field size. The adjusted underlying field size is the underlying field size that is rounded up to the nearest 8-bit boundary.Therefore, the exact size of the MPI payload is 515 bits for "P256V1Curve" used in sm2.
2.2. Curve OID
The SM2 key parameter curve OID is an array of octets that defines a named curve. The table below specifies the exact sequence of bytes for each named curve referenced in this document:
+---------------------+------+------------------------+----------+
| OID | Len | Encoding in hex format | Name |
+----------------------+------+------------------------+----------+
| 1.2.156.10197.1.301 | 8 | 2a 81 1c cf 55 01 82 2d| Sm2p256v1|
| | | | |
+----------------------+------+------------------------+----------+
2.3. Key Algorithms id
The following public key algorithm IDs are added to expand Section 9.1 of [RFC4880], "Public-Key Algorithms":
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Internet-Draft ShangMi(SM) Cipher for OpenPGP November 2024 ID Description of Algorithm -- -------------------------- TID1 SM2 public key algorithm 3. Supported Symmetric-Key Algorithm: SM4SM4 is a 128-bit symmetric block cipher (the same as AES and Twofish in OpenPGP) that supports 128-bit. This document defines the use of SM4 in OpenPGP.
+---------------------+----------------------------------------+
| SM4 Key Length | OpenPGP Symmetric-Key Algorithm Number |
+---------------------+----------------------------------------+
| 128 | TID2 |
+---------------------+----------------------------------------+
OpenPGP applications MAY implement SM4. If implemented, SM4 may be
used in any place in OpenPGP where a symmetric cipher is usable, and it is subject to the same usage requirements (such as its presence in the Preferred Symmetric Algorithms signature subpacket) as the other symmetric ciphers in OpenPGP.While the OpenPGP algorithm preferences system prevents interoperability problems with public key encrypted messages, if SM4 (or any other optional cipher) is used for encrypting private keys, there could be interoperability problems when migrating a private key from one system to another. A similar issue can arise when using an optional cipher for symmetrically encrypted messages, as this OpenPGP message type does not use the algorithm preferences system. Those using optional ciphers in this manner should take care they are using a cipher that their intended recipient can decrypt.
4. Supported Hash Algorithm: SM3
For a message m with length l ( l<2^64 ), SM3 hash algorithm generates a 256-bit hash value after padding and iterative compression.
4.1. Algorithm ID
The following algorithm ID is added to expand section 9.4 of [RFC4880], " Hash Algorithms":
ID Algorithm Text Name
-- --------- ---------
TID3 SM3[ISO-SM3] "SM3"
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Internet-Draft ShangMi(SM) Cipher for OpenPGP November 2024 4.2. Hash OIDThe table below specifies the exact sequence of bytes for the sm3 hash OID:
+------------------------+------+------------------------+------+
| OID | Len | Encoding in hex format | Name |
+------------------------+------+------------------------+------+
| 1.2.156.10197.1.401 | 8 | 2a 81 1c cf 55 01 83 11| sm3 |
| | | | |
+------------------------+------+------------------------+------+
5. IANA Considerations
IANA is requested to assign an algorithm number from the OpenPGP Public-Key Algorithms range(See section 2),a symmetric-key algorithm number from openPGP Symmetric-key Algorithm range(section 3),an hash Algorithm id from OpenPGP hash Algorithm range(section 4).
+-------+-----------------------------+------------+
| ID | Algorithm | Reference |
+-------+-----------------------------+------------+
| TID1 | SM2 public key algorithm | This doc |
+-------+-----------------------------+------------+
| TID2 | SM4 symmetric-key algorithm | This doc |
+-------+-----------------------------+------------+
| TID3 | SM3 hash algorithm | This doc |
6. Security Considerations
At the time of writing, there are no known weak keys for SM cryptographic algorithms SM2, SM3 and SM4, and no security issues have been found for these algorithms.7. References 7.1. Normative References[ISO-SM2] International Organization for Standardization, "ITSecurity techniques -- Digital signatures with appendix -- Part 3: Discrete logarithm based mechanisms", ISO/IEC 14888-3:2018, November 2018, <https://www.iso.org/standard/76382.html>.
[ISO-SM3] International Organization for Standardization, "IT Security techniques -- Hash-functions -- Part 3: Dedicated hash- functions", ISO/IEC 10118-3:2018, October 2018, <https://www.iso.org/standard/67116.html>.
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[ISO-SM4] International Organization for Standardization, "Information technology -- Security techniques -- Encryption algorithms -- Part 3: Block ciphers", ISO/IEC 18033- 3:2010, December 2010, <https://www.iso.org/standard/54531.html>.[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>.
[RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. Thayer, "OpenPGP Message Format", RFC 4880, November 2007.
[RFC6637] Jivsov, A., "Elliptic Curve Cryptography (ECC) in OpenPGP", RFC 6637, June 2012.
7.2. Informative References [GBT.32905-2016] Standardization Administration of China, "Information security technology --- SM3 cryptographic hash algorithm", GB/T 32905-2016, March 2017,<http://www.gmbz.org.cn/upload/2018-07-24/1532401392982079739.pdf>.
[GBT.32907-2016] Standardization Administration of the People's Republic of China, "Information security technology -- SM4 block cipher algorithm", GB/T 32907-2016, March 2017, <http://www.gmbz.org.cn/upload/2018-04-04/1522788048733065051.pdf>.
[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>.
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Internet-Draft ShangMi(SM) Cipher for OpenPGP November 2024 8. AcknowledgmentsThis document reference draft [draft-ietf-regext-data-escrow-03], thus, would like to thank the draft author G. Lozano. And would like to thank X. Fan, J. Chen, C. Ma, M. Chen, Z. Li who provided special important suggestions and invaluable comments. This document was prepared using 2-Word-v2.0.template.dot.
Authors' Addresses
Yao Liu CAICT No.52 Huayuan North Road, Haidian District Beijing, Beijing, 100191 China
Phone: +86 136 8310 4106 Email: liuyao1@caict.ac.cn
Zhiping Li CAICT No.52 Huayuan North Road, Haidian District Beijing, Beijing, 100191 China
Phone: +86 185 1107 1386 Email: lizhiping@caict.ac.cn
Jian Chen CAICT No.52 Huayuan North Road, Haidian District Beijing, Beijing, 100191 China
Phone: +86 138 1103 3332 Email: chenjian3@caict.ac.cn Xiaotian Fan CAICT No.52 Huayuan North Road, Haidian District Beijing, Beijing, 100191 China
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Phone: +86 134 0108 6945 Email: fanxiaotian@caict.ac.cnLiu, et al. Expires May 8, 2025 [Page 2]
