| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | EVP_PKEY-SM2, EVP_KEYMGMT-SM2, SM2
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| 6 | - EVP_PKEY keytype support for the Chinese SM2 signature and encryption algorithms
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| 7 |
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| 8 | =head1 DESCRIPTION
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| 9 |
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| 10 | The B<SM2> algorithm was first defined by the Chinese national standard GM/T
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| 11 | 0003-2012 and was later standardized by ISO as ISO/IEC 14888. B<SM2> is actually
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| 12 | an elliptic curve based algorithm. The current implementation in OpenSSL supports
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| 13 | both signature and encryption schemes via the EVP interface.
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| 14 |
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| 15 | When doing the B<SM2> signature algorithm, it requires a distinguishing identifier
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| 16 | to form the message prefix which is hashed before the real message is hashed.
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| 17 |
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| 18 | =head2 Common SM2 parameters
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| 19 |
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| 20 | SM2 uses the parameters defined in L<EVP_PKEY-EC(7)/Common EC parameters>.
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| 21 | The following parameters are different:
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| 22 |
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| 23 | =over 4
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| 24 |
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| 25 | =item "cofactor" (B<OSSL_PKEY_PARAM_EC_COFACTOR>) <unsigned integer>
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| 26 |
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| 27 | This parameter is ignored for B<SM2>.
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| 28 |
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| 29 | =item (B<OSSL_PKEY_PARAM_DEFAULT_DIGEST>) <UTF8 string>
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| 30 |
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| 31 | Getter that returns the default digest name.
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| 32 | (Currently returns "SM3" as of OpenSSL 3.0).
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| 33 |
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| 34 | =back
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| 35 |
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| 36 | =head1 NOTES
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| 37 |
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| 38 | B<SM2> signatures can be generated by using the 'DigestSign' series of APIs, for
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| 39 | instance, EVP_DigestSignInit(), EVP_DigestSignUpdate() and EVP_DigestSignFinal().
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| 40 | Ditto for the verification process by calling the 'DigestVerify' series of APIs.
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| 41 |
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| 42 | Before computing an B<SM2> signature, an B<EVP_PKEY_CTX> needs to be created,
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| 43 | and an B<SM2> ID must be set for it, like this:
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| 44 |
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| 45 | EVP_PKEY_CTX_set1_id(pctx, id, id_len);
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| 46 |
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| 47 | Before calling the EVP_DigestSignInit() or EVP_DigestVerifyInit() functions,
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| 48 | that B<EVP_PKEY_CTX> should be assigned to the B<EVP_MD_CTX>, like this:
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| 49 |
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| 50 | EVP_MD_CTX_set_pkey_ctx(mctx, pctx);
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| 51 |
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| 52 | There is normally no need to pass a B<pctx> parameter to EVP_DigestSignInit()
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| 53 | or EVP_DigestVerifyInit() in such a scenario.
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| 54 |
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| 55 | SM2 can be tested with the L<openssl-speed(1)> application since version 3.0.
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| 56 | Currently, the only valid algorithm name is B<sm2>.
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| 57 |
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| 58 | Since version 3.0, SM2 keys can be generated and loaded only when the domain
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| 59 | parameters specify the SM2 elliptic curve.
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| 60 |
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| 61 | =head1 EXAMPLES
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| 62 |
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| 63 | This example demonstrates the calling sequence for using an B<EVP_PKEY> to verify
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| 64 | a message with the SM2 signature algorithm and the SM3 hash algorithm:
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| 65 |
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| 66 | #include <openssl/evp.h>
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| 67 |
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| 68 | /* obtain an EVP_PKEY using whatever methods... */
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| 69 | mctx = EVP_MD_CTX_new();
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| 70 | pctx = EVP_PKEY_CTX_new(pkey, NULL);
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| 71 | EVP_PKEY_CTX_set1_id(pctx, id, id_len);
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| 72 | EVP_MD_CTX_set_pkey_ctx(mctx, pctx);
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| 73 | EVP_DigestVerifyInit(mctx, NULL, EVP_sm3(), NULL, pkey);
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| 74 | EVP_DigestVerifyUpdate(mctx, msg, msg_len);
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| 75 | EVP_DigestVerifyFinal(mctx, sig, sig_len)
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| 76 |
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| 77 | =head1 SEE ALSO
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| 78 |
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| 79 | L<EVP_PKEY_CTX_new(3)>,
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| 80 | L<EVP_DigestSignInit(3)>,
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| 81 | L<EVP_DigestVerifyInit(3)>,
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| 82 | L<EVP_PKEY_CTX_set1_id(3)>,
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| 83 | L<EVP_MD_CTX_set_pkey_ctx(3)>
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| 84 |
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| 85 | =head1 COPYRIGHT
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| 86 |
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| 87 | Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.
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| 88 |
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| 89 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 90 | this file except in compliance with the License. You can obtain a copy
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| 91 | in the file LICENSE in the source distribution or at
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| 92 | L<https://www.openssl.org/source/license.html>.
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| 93 |
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| 94 | =cut
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