DSA_SIGN(3) OpenSSL DSA_SIGN(3)
NAME
DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures
SYNOPSIS
#include <openssl/dsa.h>
int DSA_sign(int type, const unsigned char *dgst, int len,
unsigned char *sigret, unsigned int *siglen, DSA *dsa);
int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp, BIGNUM **rp);
int DSA_verify(int type, const unsigned char *dgst, int len,
unsigned char *sigbuf, int siglen, DSA *dsa);
DESCRIPTION
DSA_sign() computes a digital signature on the len byte message digest
dgst using the private key dsa and places its ASN.1 DER encoding at
sigret. The length of the signature is places in *siglen. sigret must
point to DSA_size(dsa) bytes of memory.
DSA_sign_setup() is defined only for backward binary compatibility and
should not be used. Since OpenSSL 1.1.0 the DSA type is opaque and the
output of DSA_sign_setup() cannot be used anyway: calling this function
will only cause overhead, and does not affect the actual signature
(pre-)computation.
DSA_verify() verifies that the signature sigbuf of size siglen matches
a given message digest dgst of size len. dsa is the signer's public
key.
The type parameter is ignored.
The random generator must be seeded when DSA_sign() (or
DSA_sign_setup()) is called. If the automatic seeding or reseeding of
the OpenSSL CSPRNG fails due to external circumstances (see RAND(7)),
the operation will fail.
RETURN VALUES
DSA_sign() and DSA_sign_setup() return 1 on success, 0 on error.
DSA_verify() returns 1 for a valid signature, 0 for an incorrect
signature and -1 on error. The error codes can be obtained by
ERR_get_error(3).
CONFORMING TO
US Federal Information Processing Standard FIPS 186 (Digital Signature
Standard, DSS), ANSI X9.30
SEE ALSO
DSA_new(3), ERR_get_error(3), RAND_bytes(3), DSA_do_sign(3), RAND(7)
COPYRIGHT
Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
1.1.1k 2021-03-25 DSA_SIGN(3)