80 lines
2.6 KiB
Plaintext
80 lines
2.6 KiB
Plaintext
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=pod
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=head1 NAME
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SM2 - Chinese SM2 signature and encryption algorithm support
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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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=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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There are several special steps that need to be done before computing an B<SM2>
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signature.
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The B<EVP_PKEY> structure will default to using ECDSA for signatures when it is
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created. It should be set to B<EVP_PKEY_SM2> by calling:
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EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2);
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Then an ID should be set by calling:
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EVP_PKEY_CTX_set1_id(pctx, id, id_len);
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When calling the EVP_DigestSignInit() or EVP_DigestVerifyInit() functions, a
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preallocated B<EVP_PKEY_CTX> should be assigned to the B<EVP_MD_CTX>. This is
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done by calling:
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EVP_MD_CTX_set_pkey_ctx(mctx, pctx);
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And normally there is 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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=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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EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2);
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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_PKEY_set_alias_type(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 2018-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (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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