// we're passed back a challenge value, Base64 encoded.
byte[] challenge = Base64.decode(line.getMessage().getBytes());
// have the authenticator evaluate and send back the encoded
// response.
sendLine(new String(Base64.encode(authenticator.evaluateChallenge(challenge))));
}
// completion or challenge are the only responses we know how to
// handle. Anything else must
// be a failure.
else {