DSA_do_sign 3 2003-07-24 0.9.9-dev OpenSSL

### NAME

DSA_do_sign, DSA_do_verify - raw DSA signature operations

### LIBRARY

libcrypto, -lcrypto

### SYNOPSIS

     #include

     DSA_SIG *DSA_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);

     int DSA_do_verify(const unsigned char *dgst, int dgst_len,
                 DSA_SIG *sig, DSA *dsa);

### DESCRIPTION

DSA_do_sign() computes a digital signature on the len byte message digest dgst using the private key dsa and returns it in a newly allocated DSA_SIG structure.

DSA_sign_setup(3) may be used to precompute part of the signing operation in case signature generation is time-critical.

DSA_do_verify() verifies that the signature sig matches a given message digest dgst of size len. dsa is the signer's public key.

### RETURN VALUES

DSA_do_sign() returns the signature, NULL on error. DSA_do_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).

### SEE ALSO

openssl_dsa(3), ERR_get_error(3), openssl_rand(3), DSA_SIG_new(3), DSA_sign(3)

### HISTORY

DSA_do_sign() and DSA_do_verify() were added in OpenSSL 0.9.3.