libcrypto/man/DSA_sign.3

 $NetBSD: DSA_sign.3,v 1.5 2026/04/08 17:06:42 christos Exp $

 -*- mode: troff; coding: utf-8 -*-
 Automatically generated by Pod::Man v6.0.2 (Pod::Simple 3.45)

 Standard preamble:
 ========================================================================
..
..

..
 \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>.
. ds C` ""
. ds C' ""
'br\}
. ds C`
. ds C'
'br\}

 Escape single quotes in literal strings from groff's Unicode transform.

 If the F register is >0, we'll generate index entries on stderr for
 titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
 entries marked with X<> in POD. Of course, you'll have to process the
 output yourself in some meaningful fashion.

 Avoid warning from groff about undefined register 'F'.
..
.nr rF 0
. if \nF \{\
. de IX
. tm Index:\\$1\t\\n%\t"\\$2"
..
. if !\nF==2 \{\
. nr % 0
. nr F 2
. \}
. \}
.\}
.rr rF

 Required to disable full justification in groff 1.23.0.
 ========================================================================

 Title "DSA_sign 3"  DSA_sign 3 2026-04-07 3.5.6 OpenSSL
 For nroff, turn off justification. Always turn off hyphenation; it makes
 way too many mistakes in technical documents.
.nh
 NAME
DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures
 SYNOPSIS
 Header "SYNOPSIS" .Vb 1
 #include <openssl/dsa.h>
.Ve

The following functions have been deprecated since OpenSSL 3.0, and can be
hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value,
see openssl_user_macros\|(7):

.Vb 2
 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);
.Ve
 DESCRIPTION
 Header "DESCRIPTION" All of the functions described on this page are deprecated.
Applications should instead use EVP_PKEY_sign_init\|(3), EVP_PKEY_sign\|(3),
\fBEVP_PKEY_verify_init\|(3) and EVP_PKEY_verify\|(3).

\fBDSA_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.

\fBDSA_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
\fBDSA_sign_setup() cannot be used anyway: calling this function will only
cause overhead, and does not affect the actual signature
(pre-)computation.

\fBDSA_verify() verifies that the signature sigbuf of size siglen
matches a given message digest dgst of size len.
\fBdsa is the signer\*(Aqs 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"
 Header "RETURN VALUES" \fBDSA_sign() and DSA_sign_setup() return 1 on success, 0 on error.
\fBDSA_verify() returns 1 for a valid signature, 0 for an incorrect
signature and -1 on error. The error codes can be obtained by
\fBERR_get_error\|(3).
 "CONFORMING TO"
 Header "CONFORMING TO" US Federal Information Processing Standard FIPS186-4 (Digital Signature
Standard, DSS), ANSI X9.30
 "SEE ALSO"
 Header "SEE ALSO" \fBDSA_new\|(3), ERR_get_error\|(3), RAND_bytes\|(3),
\fBDSA_do_sign\|(3),
\fBRAND\|(7)
 HISTORY
 Header "HISTORY" All of these functions were deprecated in OpenSSL 3.0.
 COPYRIGHT
 Header "COPYRIGHT" Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (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>.