def test_fromBlobRSA(self):
        """
        A public RSA key is correctly generated from a public key blob.
        """
        rsaPublicData = {
            'n': keydata.RSAData['n'],
            'e': keydata.RSAData['e'],
            }
        rsaBlob = (
            common.NS(b'ssh-rsa') +
            common.MP(rsaPublicData['e']) +
            common.MP(rsaPublicData['n'])
            )

        rsaKey = keys.Key.fromString(rsaBlob)

        self.assertTrue(rsaKey.isPublic())
        self.assertEqual(rsaPublicData, rsaKey.data())

        A public RSA key is correctly generated from a public key blob.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_keys.py