# man > SM2(7)

[_EVP_PKEY-SM2_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPPKEY-SM2/7SSL/markdown)                             OpenSSL                            [_EVP_PKEY-SM2_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPPKEY-SM2/7SSL/markdown)

## 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)](https://www.chedong.com/phpMan.php/man/EVPPKEY-EC/7/markdown).  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)](https://www.chedong.com/phpMan.php/man/openssl-speed/1/markdown) 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)](https://www.chedong.com/phpMan.php/man/EVPPKEYCTXnew/3/markdown), [**EVP_DigestSignInit**(3)](https://www.chedong.com/phpMan.php/man/EVPDigestSignInit/3/markdown), [**EVP_DigestVerifyInit**(3)](https://www.chedong.com/phpMan.php/man/EVPDigestVerifyInit/3/markdown), [**EVP_PKEY_CTX_set1_id**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEYCTXset1id/3/markdown),
       [**EVP_MD_CTX_set_pkey_ctx**(3)](https://www.chedong.com/phpMan.php/man/EVPMDCTXsetpkeyctx/3/markdown)

## 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)](https://www.chedong.com/phpMan.php/man/EVPPKEY-SM2/7SSL/markdown)