man > EVP_PKEY-SM2(7SSL)

EVP_PKEY-SM2(7SSL)                             OpenSSL                            EVP_PKEY-SM2(7SSL)

NAME
       EVP_PKEY-SM2, EVP_KEYMGMT-SM2, SM2 - EVP_PKEY keytype support for the Chinese SM2 signature
       and encryption algorithms

DESCRIPTION
       The SM2 algorithm was first defined by the Chinese national standard GM/T 0003-2012 and was
       later standardized by ISO as ISO/IEC 14888. SM2 is actually an elliptic curve based
       algorithm. The current implementation in OpenSSL supports both signature and encryption
       schemes via the EVP interface.

       When doing the SM2 signature algorithm, it requires a distinguishing identifier to form the
       message prefix which is hashed before the real message is hashed.

   Common SM2 parameters
       SM2 uses the parameters defined in "Common EC parameters" in EVP_PKEY-EC(7).  The following
       parameters are different:

       "cofactor" (OSSL_PKEY_PARAM_EC_COFACTOR) <unsigned integer>
           This parameter is ignored for SM2.

       (OSSL_PKEY_PARAM_DEFAULT_DIGEST) <UTF8 string>
           Getter  that  returns  the  default  digest name.  (Currently returns "SM3" as of OpenSSL
           3.0).

NOTES
       SM2 signatures can be generated by using the  'DigestSign'  series  of  APIs,  for  instance,
       EVP_DigestSignInit(),   EVP_DigestSignUpdate()  and  EVP_DigestSignFinal().   Ditto  for  the
       verification process by calling the 'DigestVerify' series of APIs.

       Before computing an SM2 signature, an EVP_PKEY_CTX needs to be created, and an SM2 ID must be
       set for it, like this:

        EVP_PKEY_CTX_set1_id(pctx, id, id_len);

       Before  calling  the   EVP_DigestSignInit()   or   EVP_DigestVerifyInit()   functions,   that
       EVP_PKEY_CTX should be assigned to the EVP_MD_CTX, like this:

        EVP_MD_CTX_set_pkey_ctx(mctx, pctx);

       There   is   normally   no   need  to  pass  a  pctx  parameter  to  EVP_DigestSignInit()  or
       EVP_DigestVerifyInit() in such a scenario.

       SM2 can be tested with the openssl-speed(1) application since version  3.0.   Currently,  the
       only valid algorithm name is sm2.

       Since  version  3.0,  SM2  keys  can  be generated and loaded only when the domain parameters
       specify the SM2 elliptic curve.

EXAMPLES
       This example demonstrates the calling sequence for using an EVP_PKEY to verify a message with
       the SM2 signature algorithm and the SM3 hash algorithm:

        #include <openssl/evp.h>

        /* obtain an EVP_PKEY using whatever methods... */
        mctx = EVP_MD_CTX_new();
        pctx = EVP_PKEY_CTX_new(pkey, NULL);
        EVP_PKEY_CTX_set1_id(pctx, id, id_len);
        EVP_MD_CTX_set_pkey_ctx(mctx, pctx);
        EVP_DigestVerifyInit(mctx, NULL, EVP_sm3(), NULL, pkey);
        EVP_DigestVerifyUpdate(mctx, msg, msg_len);
        EVP_DigestVerifyFinal(mctx, sig, sig_len)

SEE ALSO
       EVP_PKEY_CTX_new(3), EVP_DigestSignInit(3), EVP_DigestVerifyInit(3), EVP_PKEY_CTX_set1_id(3),
       EVP_MD_CTX_set_pkey_ctx(3)

COPYRIGHT
       Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file  except  in
       compliance  with  the  License.   You  can  obtain  a  copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.

3.0.13                                       2026-07-29                           EVP_PKEY-SM2(7SSL)