DSA_sign(3)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
The DSA_sign() function 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 placed in
*siglen. The sigret must point to DSA_size(dsa) bytes of memory.
The DSA_sign_setup() function may be used to precompute part of the
signing operation in case signature generation is time-critical. It
expects dsa to contain DSA parameters. It places the precomputed values
in newly allocated BIGNUMs at *kinvp and *rp, after freeing the old
ones unless *kinvp and *rp are NULL. These values may be passed to
DSA_sign() in dsa->kinv and dsa->r. The ctx is a pre-allocated BN_CTX
or NULL.
The DSA_verify() function verifies that the signature sigbuf of size
siglen matches a given message digest dgst of size len. The dsa is the
signer's public key.
The type parameter is ignored.
The PRNG must be seeded before the DSA_sign() or DSA_sign_setup() func‐
tion is called.
These functions conform to US Federal Information Processing Standard
FIPS 186 (Digital Signature Standard, DSS), ANSI X9.30.
RETURN VALUES
The DSA_sign() and DSA_sign_setup() functions return 1 on success, 0 on
error. The DSA_verify() function returns 1 for a valid signature, 0 for
an incorrect signature, and -1 on error. The error codes can be
obtained from ERR_get_error().
HISTORY
The DSA_sign() and DSA_verify() functions are available in all versions
of SSLeay. The DSA_sign_setup() function was added in SSLeay 0.8.
SEE ALSO
Functions: dsa(3), err(3), rand(3), DSA_do_sign(3)DSA_sign(3)