1SM2(7)                              OpenSSL                             SM2(7)
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NAME

6       SM2 - Chinese SM2 signature and encryption algorithm support
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DESCRIPTION

9       The SM2 algorithm was first defined by the Chinese national standard
10       GM/T 0003-2012 and was later standardized by ISO as ISO/IEC 14888. SM2
11       is actually an elliptic curve based algorithm. The current
12       implementation in OpenSSL supports both signature and encryption
13       schemes via the EVP interface.
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15       When doing the SM2 signature algorithm, it requires a distinguishing
16       identifier to form the message prefix which is hashed before the real
17       message is hashed.
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NOTES

20       SM2 signatures can be generated by using the 'DigestSign' series of
21       APIs, for instance, EVP_DigestSignInit(), EVP_DigestSignUpdate() and
22       EVP_DigestSignFinal().  Ditto for the verification process by calling
23       the 'DigestVerify' series of APIs.
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25       There are several special steps that need to be done before computing
26       an SM2 signature.
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28       The EVP_PKEY structure will default to using ECDSA for signatures when
29       it is created. It should be set to EVP_PKEY_SM2 by calling:
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31        EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2);
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33       Then an ID should be set by calling:
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35        EVP_PKEY_CTX_set1_id(pctx, id, id_len);
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37       When calling the EVP_DigestSignInit() or EVP_DigestVerifyInit()
38       functions, a preallocated EVP_PKEY_CTX should be assigned to the
39       EVP_MD_CTX. This is done by calling:
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41        EVP_MD_CTX_set_pkey_ctx(mctx, pctx);
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43       And normally there is no need to pass a pctx parameter to
44       EVP_DigestSignInit() or EVP_DigestVerifyInit() in such a scenario.
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EXAMPLES

47       This example demonstrates the calling sequence for using an EVP_PKEY to
48       verify a message with the SM2 signature algorithm and the SM3 hash
49       algorithm:
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51        #include <openssl/evp.h>
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53        /* obtain an EVP_PKEY using whatever methods... */
54        EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2);
55        mctx = EVP_MD_CTX_new();
56        pctx = EVP_PKEY_CTX_new(pkey, NULL);
57        EVP_PKEY_CTX_set1_id(pctx, id, id_len);
58        EVP_MD_CTX_set_pkey_ctx(mctx, pctx);;
59        EVP_DigestVerifyInit(mctx, NULL, EVP_sm3(), NULL, pkey);
60        EVP_DigestVerifyUpdate(mctx, msg, msg_len);
61        EVP_DigestVerifyFinal(mctx, sig, sig_len)
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SEE ALSO

64       EVP_PKEY_CTX_new(3), EVP_PKEY_set_alias_type(3), EVP_DigestSignInit(3),
65       EVP_DigestVerifyInit(3), EVP_PKEY_CTX_set1_id(3),
66       EVP_MD_CTX_set_pkey_ctx(3)
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69       Copyright 2018-2020 The OpenSSL Project Authors. All Rights Reserved.
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71       Licensed under the OpenSSL license (the "License").  You may not use
72       this file except in compliance with the License.  You can obtain a copy
73       in the file LICENSE in the source distribution or at
74       <https://www.openssl.org/source/license.html>.
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781.1.1k                            2021-03-26                            SM2(7)
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