Updated: 2021/Apr/14

DSA_sign(3)                         OpenSSL                        DSA_sign(3)

       DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures

       libcrypto, -lcrypto

        #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);

       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

       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

       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.

       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

       US Federal Information Processing Standard FIPS 186 (Digital Signature
       Standard, DSS), ANSI X9.30

       DSA_new(3), ERR_get_error(3), RAND_bytes(3), DSA_do_sign(3), RAND(7)

       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

1.1.1i                            2020-01-23                       DSA_sign(3)