1=pod 2 3=head1 NAME 4 5DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures 6 7=head1 SYNOPSIS 8 9 #include <openssl/dsa.h> 10 11 int DSA_sign(int type, const unsigned char *dgst, int len, 12 unsigned char *sigret, unsigned int *siglen, DSA *dsa); 13 14 int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp, BIGNUM **rp); 15 16 int DSA_verify(int type, const unsigned char *dgst, int len, 17 unsigned char *sigbuf, int siglen, DSA *dsa); 18 19=head1 DESCRIPTION 20 21DSA_sign() computes a digital signature on the B<len> byte message 22digest B<dgst> using the private key B<dsa> and places its ASN.1 DER 23encoding at B<sigret>. The length of the signature is places in 24*B<siglen>. B<sigret> must point to DSA_size(B<dsa>) bytes of memory. 25 26DSA_sign_setup() is defined only for backward binary compatibility and 27should not be used. 28Since OpenSSL 1.1.0 the DSA type is opaque and the output of 29DSA_sign_setup() cannot be used anyway: calling this function will only 30cause overhead, and does not affect the actual signature 31(pre-)computation. 32 33DSA_verify() verifies that the signature B<sigbuf> of size B<siglen> 34matches a given message digest B<dgst> of size B<len>. 35B<dsa> is the signer's public key. 36 37The B<type> parameter is ignored. 38 39The random generator must be seeded when DSA_sign() (or DSA_sign_setup()) 40is called. 41If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to 42external circumstances (see L<RAND(7)>), the operation will fail. 43 44=head1 RETURN VALUES 45 46DSA_sign() and DSA_sign_setup() return 1 on success, 0 on error. 47DSA_verify() returns 1 for a valid signature, 0 for an incorrect 48signature and -1 on error. The error codes can be obtained by 49L<ERR_get_error(3)>. 50 51=head1 CONFORMING TO 52 53US Federal Information Processing Standard FIPS 186 (Digital Signature 54Standard, DSS), ANSI X9.30 55 56=head1 SEE ALSO 57 58L<DSA_new(3)>, L<ERR_get_error(3)>, L<RAND_bytes(3)>, 59L<DSA_do_sign(3)>, 60L<RAND(7)> 61 62=head1 COPYRIGHT 63 64Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved. 65 66Licensed under the OpenSSL license (the "License"). You may not use 67this file except in compliance with the License. You can obtain a copy 68in the file LICENSE in the source distribution or at 69L<https://www.openssl.org/source/license.html>. 70 71=cut 72