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98 lines
3.2 KiB
Plaintext
98 lines
3.2 KiB
Plaintext
=pod
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=head1 NAME
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EVP_PKEY-SM2, EVP_KEYMGMT-SM2, SM2
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- EVP_PKEY keytype support for the Chinese SM2 signature and encryption algorithms
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=head1 DESCRIPTION
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The B<SM2> algorithm was first defined by the Chinese national standard GM/T
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0003-2012 and was later standardized by ISO as ISO/IEC 14888. B<SM2> is actually
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an elliptic curve based algorithm. The current implementation in OpenSSL supports
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both signature and encryption schemes via the EVP interface.
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When doing the B<SM2> signature algorithm, it requires a distinguishing identifier
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to form the message prefix which is hashed before the real message is hashed.
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=head2 Common SM2 parameters
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SM2 uses the parameters defined in L<EVP_PKEY-EC(7)/Common EC parameters>.
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The following parameters are different:
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=over 4
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=item "cofactor" (B<OSSL_PKEY_PARAM_EC_COFACTOR>) <unsigned integer>
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This parameter is ignored for B<SM2>.
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=item (B<OSSL_PKEY_PARAM_DEFAULT_DIGEST>) <UTF8 string>
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Getter that returns the default digest name.
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(Currently returns "SM3" as of OpenSSL 3.0).
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=back
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=head1 NOTES
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B<SM2> signatures can be generated by using the 'DigestSign' series of APIs, for
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instance, EVP_DigestSignInit(), EVP_DigestSignUpdate() and EVP_DigestSignFinal().
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Ditto for the verification process by calling the 'DigestVerify' series of APIs.
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Note that the SM2 algorithm requires the presence of the public key for signatures,
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as such the B<OSSL_PKEY_PARAM_PUB_KEY> option must be set on any key used in signature
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generation.
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Before computing an B<SM2> signature, an B<EVP_PKEY_CTX> needs to be created,
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and an B<SM2> ID must be set for it, like this:
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EVP_PKEY_CTX_set1_id(pctx, id, id_len);
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Before calling the EVP_DigestSignInit() or EVP_DigestVerifyInit() functions,
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that B<EVP_PKEY_CTX> should be assigned to the B<EVP_MD_CTX>, like this:
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EVP_MD_CTX_set_pkey_ctx(mctx, pctx);
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There is normally no need to pass a B<pctx> parameter to EVP_DigestSignInit()
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or EVP_DigestVerifyInit() in such a scenario.
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SM2 can be tested with the L<openssl-speed(1)> application since version 3.0.
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Currently, the only valid algorithm name is B<sm2>.
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Since version 3.0, SM2 keys can be generated and loaded only when the domain
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parameters specify the SM2 elliptic curve.
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=head1 EXAMPLES
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This example demonstrates the calling sequence for using an B<EVP_PKEY> to verify
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a message with the SM2 signature algorithm and the SM3 hash algorithm:
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#include <openssl/evp.h>
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/* obtain an EVP_PKEY using whatever methods... */
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mctx = EVP_MD_CTX_new();
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pctx = EVP_PKEY_CTX_new(pkey, NULL);
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EVP_PKEY_CTX_set1_id(pctx, id, id_len);
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EVP_MD_CTX_set_pkey_ctx(mctx, pctx);
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EVP_DigestVerifyInit(mctx, NULL, EVP_sm3(), NULL, pkey);
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EVP_DigestVerifyUpdate(mctx, msg, msg_len);
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EVP_DigestVerifyFinal(mctx, sig, sig_len)
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=head1 SEE ALSO
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L<EVP_PKEY_CTX_new(3)>,
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L<EVP_DigestSignInit(3)>,
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L<EVP_DigestVerifyInit(3)>,
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L<EVP_PKEY_CTX_set1_id(3)>,
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L<EVP_MD_CTX_set_pkey_ctx(3)>
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=head1 COPYRIGHT
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Copyright 2018-2024 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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