def sha1_hexdigest(self):
        # type: () -> str
        """
        A SHA-1 digest of the whole object for easy differentiation.

        .. versionadded:: 18.1.0
        """
        if self._sha1_hexdigest is None:
            self._sha1_hexdigest = hashlib.sha1(self._pem_bytes).hexdigest()

        return self._sha1_hexdigest
A SHA-1 digest of the whole object for easy differentiation.

        .. versionadded:: 18.1.0