'Test that private key authentication fails when the public key
is invalid.'

def test_failedPrivateKeyAuthenticationWithoutSignature(self):

    blob = keys.Key.fromString(keydata.publicDSA_openssh).blob()
    packet = (((((NS('foo') + NS('none')) + NS('publickey')) + '\x00') + NS('ssh-dsa')) + NS(blob))
    d = self.authServer.ssh_USERAUTH_REQUEST(packet)
    return d.addCallback(self._checkFailed)
