1=pod 2 3=head1 NAME 4 5EVP_PKEY-SM2, EVP_KEYMGMT-SM2, SM2 6- EVP_PKEY keytype support for the Chinese SM2 signature and encryption algorithms 7 8=head1 DESCRIPTION 9 10The B<SM2> algorithm was first defined by the Chinese national standard GM/T 110003-2012 and was later standardized by ISO as ISO/IEC 14888. B<SM2> is actually 12an elliptic curve based algorithm. The current implementation in OpenSSL supports 13both signature and encryption schemes via the EVP interface. 14 15When doing the B<SM2> signature algorithm, it requires a distinguishing identifier 16to form the message prefix which is hashed before the real message is hashed. 17 18=head2 Common SM2 parameters 19 20SM2 uses the parameters defined in L<EVP_PKEY-EC(7)/Common EC parameters>. 21The following parameters are different: 22 23=over 4 24 25=item "cofactor" (B<OSSL_PKEY_PARAM_EC_COFACTOR>) <unsigned integer> 26 27This parameter is ignored for B<SM2>. 28 29=item (B<OSSL_PKEY_PARAM_DEFAULT_DIGEST>) <UTF8 string> 30 31Getter that returns the default digest name. 32(Currently returns "SM3" as of OpenSSL 3.0). 33 34=back 35 36=head1 NOTES 37 38B<SM2> signatures can be generated by using the 'DigestSign' series of APIs, for 39instance, EVP_DigestSignInit(), EVP_DigestSignUpdate() and EVP_DigestSignFinal(). 40Ditto for the verification process by calling the 'DigestVerify' series of APIs. 41Note that the SM2 algorithm requires the presence of the public key for signatures, 42as such the B<OSSL_PKEY_PARAM_PUB_KEY> option must be set on any key used in signature 43generation. 44 45Before computing an B<SM2> signature, an B<EVP_PKEY_CTX> needs to be created, 46and an B<SM2> ID must be set for it, like this: 47 48 EVP_PKEY_CTX_set1_id(pctx, id, id_len); 49 50Before calling the EVP_DigestSignInit() or EVP_DigestVerifyInit() functions, 51that B<EVP_PKEY_CTX> should be assigned to the B<EVP_MD_CTX>, like this: 52 53 EVP_MD_CTX_set_pkey_ctx(mctx, pctx); 54 55There is normally no need to pass a B<pctx> parameter to EVP_DigestSignInit() 56or EVP_DigestVerifyInit() in such a scenario. 57 58SM2 can be tested with the L<openssl-speed(1)> application since version 3.0. 59Currently, the only valid algorithm name is B<sm2>. 60 61Since version 3.0, SM2 keys can be generated and loaded only when the domain 62parameters specify the SM2 elliptic curve. 63 64=head1 EXAMPLES 65 66This example demonstrates the calling sequence for using an B<EVP_PKEY> to verify 67a message with the SM2 signature algorithm and the SM3 hash algorithm: 68 69 #include <openssl/evp.h> 70 71 /* obtain an EVP_PKEY using whatever methods... */ 72 mctx = EVP_MD_CTX_new(); 73 pctx = EVP_PKEY_CTX_new(pkey, NULL); 74 EVP_PKEY_CTX_set1_id(pctx, id, id_len); 75 EVP_MD_CTX_set_pkey_ctx(mctx, pctx); 76 EVP_DigestVerifyInit(mctx, NULL, EVP_sm3(), NULL, pkey); 77 EVP_DigestVerifyUpdate(mctx, msg, msg_len); 78 EVP_DigestVerifyFinal(mctx, sig, sig_len) 79 80=head1 SEE ALSO 81 82L<EVP_PKEY_CTX_new(3)>, 83L<EVP_DigestSignInit(3)>, 84L<EVP_DigestVerifyInit(3)>, 85L<EVP_PKEY_CTX_set1_id(3)>, 86L<EVP_MD_CTX_set_pkey_ctx(3)> 87 88=head1 COPYRIGHT 89 90Copyright 2018-2024 The OpenSSL Project Authors. All Rights Reserved. 91 92Licensed under the Apache License 2.0 (the "License"). You may not use 93this file except in compliance with the License. You can obtain a copy 94in the file LICENSE in the source distribution or at 95L<https://www.openssl.org/source/license.html>. 96 97=cut 98