Verifies the signature on the encrypted cipher block.

    This method returns True if the signature verifies correctly with
    the key given.

    Args:
      remote_public_key: The remote public key.

    Returns:
      None
    Raises:
      rdf_crypto.VerificationError: A signature and a key were both given but
                                    verification fails.

def VerifyCipherSignature(self, remote_public_key):
    """Verifies the signature on the encrypted cipher block.

    This method returns True if the signature verifies correctly with
    the key given.

    Args:
      remote_public_key: The remote public key.

    Returns:
      None
    Raises:
      rdf_crypto.VerificationError: A signature and a key were both given but
                                    verification fails.

    """
    if self.cipher_metadata.signature and remote_public_key:

      stats_collector_instance.Get().IncrementCounter("grr_rsa_operations")
      remote_public_key.Verify(self.serialized_cipher,
                               self.cipher_metadata.signature)
      return True