def verify(authenticator, message)
      auth = authenticator.to_s
      Util.check_length(auth, tag_bytes, "Provided authenticator")
      verify_message(auth, message) || raise(BadAuthenticatorError, "Invalid authenticator provided, message is corrupt")
    end
def verify(authenticator, message)
      auth = authenticator.to_s
      Util.check_length(auth, tag_bytes, "Provided authenticator")
      verify_message(auth, message) || raise(BadAuthenticatorError, "Invalid authenticator provided, message is corrupt")
    end
Verifies the given authenticator with the message.

 @param [#to_str] authenticator to be checked
 @param [#to_str] message the message to be authenticated

 @raise [BadAuthenticatorError] if the tag isn't valid
 @raise [LengthError]  if the tag is of the wrong length

 @return [Boolean] Was it valid?