code: def sign(self, identity, blob):
          
          if identity.identity_dict['proto'] in {'ssh'}:
              digest = hashlib.sha256(blob).digest()
          else:
              digest = blob
          return self.sk.sign_digest_deterministic(digest=digest,
                                                   hashfunc=hashlib.sha256)
docs: Sign given blob and return the signature (as bytes).