f987a4dd89
The manual pages require for some API functions that the 'random number
generator must be seeded' before calling the function. Initially, this
was meant literally, i.e. the OpenSSL CSPRNG had to be seeded manually
before calling these functions.
Since version 1.1.1, the CSPRNG is seeded automatically on first use,
so it's not the responsibility of the programmer anymore. Still, he
needs to be aware that the seeding might fail.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/9257)
(cherry picked from commit 262c00882a)
71 lines
2.2 KiB
Text
71 lines
2.2 KiB
Text
=pod
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=head1 NAME
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DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures
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=head1 SYNOPSIS
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#include <openssl/dsa.h>
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int DSA_sign(int type, const unsigned char *dgst, int len,
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unsigned char *sigret, unsigned int *siglen, DSA *dsa);
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int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp, BIGNUM **rp);
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int DSA_verify(int type, const unsigned char *dgst, int len,
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unsigned char *sigbuf, int siglen, DSA *dsa);
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=head1 DESCRIPTION
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DSA_sign() computes a digital signature on the B<len> byte message
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digest B<dgst> using the private key B<dsa> and places its ASN.1 DER
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encoding at B<sigret>. The length of the signature is places in
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*B<siglen>. B<sigret> must point to DSA_size(B<dsa>) bytes of memory.
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DSA_sign_setup() is defined only for backward binary compatibility and
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should not be used.
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Since OpenSSL 1.1.0 the DSA type is opaque and the output of
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DSA_sign_setup() cannot be used anyway: calling this function will only
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cause overhead, and does not affect the actual signature
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(pre-)computation.
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DSA_verify() verifies that the signature B<sigbuf> of size B<siglen>
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matches a given message digest B<dgst> of size B<len>.
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B<dsa> is the signer's public key.
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The B<type> parameter is ignored.
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The random generator must be seeded when DSA_sign() (or DSA_sign_setup())
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is called.
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If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
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external circumstances (see L<RAND(7)>), the operation will fail.
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=head1 RETURN VALUES
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DSA_sign() and DSA_sign_setup() return 1 on success, 0 on error.
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DSA_verify() returns 1 for a valid signature, 0 for an incorrect
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signature and -1 on error. The error codes can be obtained by
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L<ERR_get_error(3)>.
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=head1 CONFORMING TO
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US Federal Information Processing Standard FIPS 186 (Digital Signature
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Standard, DSS), ANSI X9.30
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=head1 SEE ALSO
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L<DSA_new(3)>, L<ERR_get_error(3)>, L<RAND_bytes(3)>,
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L<DSA_do_sign(3)>,
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L<RAND(7)>
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=head1 COPYRIGHT
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Copyright 2000-2018 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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