Updated: 2022/Sep/29

Please read Privacy Policy. It's for your privacy.

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



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>.



3.0.12                            2023-05-07                   EVP_PKEY-SM2(7)