NAME

       DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures

SYNOPSIS

        #include <openssl/dsa.h>

       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):

        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

       All of the functions described on this page are deprecated.  Applications should instead use
       EVP_PKEY_sign_init(3), EVP_PKEY_sign(3), EVP_PKEY_verify_init(3) and EVP_PKEY_verify(3).

       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 FIPS186-4 (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)

HISTORY

       All of these functions were deprecated in OpenSSL 3.0.

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>.

3.4.1                                              2025-04-03                                     DSA_SIGN(3SSL)