Create a public blob from a network `.Message`.

        Specifically, a cert-bearing pubkey auth packet, because by definition
        OpenSSH-style certificates 'are' their own network representation."

def from_message(cls, message):
        """
        Create a public blob from a network `.Message`.

        Specifically, a cert-bearing pubkey auth packet, because by definition
        OpenSSH-style certificates 'are' their own network representation."
        """
        type_ = message.get_text()
        return cls(type_=type_, blob=message.asbytes())