SM2(7SSL) OpenSSL SM2(7SSL)
NAME
SM2 - Chinese SM2 signature and encryption algorithm support
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.
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.
There are several special steps that need to be done before computing
an SM2 signature.
The EVP_PKEY structure will default to using ECDSA for signatures when
it is created. It should be set to EVP_PKEY_SM2 by calling:
EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2);
Then an ID should be set by calling:
EVP_PKEY_CTX_set1_id(pctx, id, id_len);
When calling the EVP_DigestSignInit() or EVP_DigestVerifyInit()
functions, a pre-allocated EVP_PKEY_CTX should be assigned to the
EVP_MD_CTX. This is done by calling:
EVP_MD_CTX_set_pkey_ctx(mctx, pctx);
And normally there is no need to pass a pctx parameter to
EVP_DigestSignInit() or EVP_DigestVerifyInit() in such a scenario.
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... */
EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2);
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_PKEY_set_alias_type(3), EVP_DigestSignInit(3),
EVP_DigestVerifyInit(3), EVP_PKEY_CTX_set1_id(3),
EVP_MD_CTX_set_pkey_ctx(3)
COPYRIGHT
Copyright 2018-2019 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (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>.
1.1.1g 2020-04-21 SM2(7SSL)