=pod =head1 NAME DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures =head1 SYNOPSIS #include 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); =head1 DESCRIPTION DSA_sign() computes a digital signature on the B byte message digest B using the private key B and places its ASN.1 DER encoding at B. The length of the signature is places in *B. B must point to DSA_size(B) bytes of memory. DSA_sign_setup() may be used to precompute part of the signing operation in case signature generation is time-critical. It expects B to contain DSA parameters. It places the precomputed values in newly allocated Bs at *B and *B, after freeing the old ones unless *B and *B are NULL. These values may be passed to DSA_sign() in Bkinv> and Br>. B is a pre-allocated B or NULL. DSA_verify() verifies that the signature B of size B matches a given message digest B of size B. B is the signer's public key. The B parameter is ignored. The PRNG must be seeded before DSA_sign() (or DSA_sign_setup()) is called. =head1 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 L. =head1 CONFORMING TO US Federal Information Processing Standard FIPS 186 (Digital Signature Standard, DSS), ANSI X9.30 =head1 SEE ALSO L, L, L, L =head1 HISTORY DSA_sign() and DSA_verify() are available in all versions of SSLeay. DSA_sign_setup() was added in SSLeay 0.8. =cut