Verifies given signature on given digest
        Returns True if Ok, False if don't match
        Keyword arguments allows to set algorithm-specific
        parameters

def verify(self, digest, signature, **kwargs):
        """
        Verifies given signature on given digest
        Returns True if Ok, False if don't match
        Keyword arguments allows to set algorithm-specific
        parameters
        """
        ctx = libcrypto.EVP_PKEY_CTX_new(self.key, None)
        if ctx is None:
            raise PKeyError("Initailizing verify context")
        if libcrypto.EVP_PKEY_verify_init(ctx) < 1:
            raise PKeyError("verify_init")
        self._configure_context(ctx, kwargs)
        ret = libcrypto.EVP_PKEY_verify(ctx, signature, len(signature), digest,
                                        len(digest))
        if ret < 0:
            raise PKeyError("Signature verification")
        libcrypto.EVP_PKEY_CTX_free(ctx)
        return ret > 0