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 PRNG must be seeded before DSA_sign() (or DSA_sign_setup()) is called.

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)

COPYRIGHT

       Copyright 2000-2018 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>.