@deftypefun {int} {gnutls_privkey_sign_hash} (gnutls_privkey_t @var{signer}, gnutls_digest_algorithm_t @var{hash_algo}, unsigned int @var{flags}, const gnutls_datum_t * @var{hash_data}, gnutls_datum_t * @var{signature})

@var{signer}: Holds the signer's key

@var{hash_algo}: The hash algorithm used

@var{flags}: Zero or one of @code{gnutls_privkey_flags_t} 

@var{hash_data}: holds the data to be signed

@var{signature}: will contain newly allocated signature

This function will sign the given hashed data using a signature algorithm

supported by the private key. Signature algorithms are always used

together with a hash functions.  Different hash functions may be

used for the RSA algorithm, but only SHA-XXX for the DSA keys.

You may use @code{gnutls_pubkey_get_preferred_hash_algorithm()}  to determine

the hash algorithm.

The flags may be @code{GNUTLS_PRIVKEY_SIGN_FLAG_TLS1_RSA}  or @code{GNUTLS_PRIVKEY_SIGN_FLAG_RSA_PSS} .

In the former case this function will ignore  @code{hash_algo} and perform a raw PKCS1 signature,

and in the latter an RSA-PSS signature will be generated.

Note that, not all algorithm support signing already hashed data. When

signing with Ed25519, @code{gnutls_privkey_sign_data()}  should be used.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a

negative error value.

@strong{Since:} 2.12.0

@end deftypefun