SilcBool silc_pkcs_verify(SilcPublicKey public_key,
                              unsigned char *signature,
                              SilcUInt32 signature_len,
                              unsigned char *data,
                              SilcUInt32 data_len, SilcHash hash);

    Verifies signature.  Returns FALSE on error.  The 'signature' is
    verified against the 'data'.  If the `hash' is non-NULL then the `data'
    will hashed before verification.  If the `hash' is NULL, then the
    hash algorithm to be used is retrieved from the signature.  If it
    isn't present in the signature the verification is done as is without
    hashing.