public AuthenticatedSocket(InetAddress ia, int port, MessageDigest md, byte[] secret)
      throws IOException, AuthenticationException {
    super(ia, port);

    try {
      OutputStream output = this.getOutputStream();
      InputStream input = this.getInputStream();

      // Get challenge length
      byte[] challengeSize = new byte[4];
      input.read(challengeSize);

      // Receive random challenge string
      byte[] challenge = new byte[Bytes.toInt(challengeSize)];
      input.read(challenge);

      // Generate MD5 hash
      byte[] append = Bytes.append(challenge, secret);
      byte[] hash = md.digest(append);

      // Send time and hash strings
      output.write(hash);
    } catch (Exception e) {
      throw new AuthenticationException("Authentication failed: " + e.getMessage());
    }
  }
  private void _putObjectField(String name, Object val) {

    if (dbOnlyField(name) || name.equals("_transientFields")) return;

    if (DEBUG) System.out.println("\t put thing : " + name);

    if (name.equals("$where") && val instanceof String) {
      _put(CODE, name);
      _putValueString(val.toString());
      return;
    }

    val = Bytes.applyEncodingHooks(val);

    if (val == null) putNull(name);
    else if (val instanceof Date) putDate(name, (Date) val);
    else if (val instanceof Number) putNumber(name, (Number) val);
    else if (val instanceof String) putString(name, val.toString());
    else if (val instanceof ObjectId) putObjectId(name, (ObjectId) val);
    else if (val instanceof DBObject) putObject(name, (DBObject) val);
    else if (val instanceof Boolean) putBoolean(name, (Boolean) val);
    else if (val instanceof Pattern) putPattern(name, (Pattern) val);
    else if (val instanceof DBRegex) {
      putDBRegex(name, (DBRegex) val);
    } else if (val instanceof Map) putMap(name, (Map) val);
    else if (val instanceof List) putList(name, (List) val);
    else if (val instanceof byte[]) putBinary(name, (byte[]) val);
    else if (val instanceof DBBinary) putBinary(name, (DBBinary) val);
    else if (val.getClass().isArray()) putList(name, Arrays.asList((Object[]) val));
    else if (val instanceof DBPointer) {

      // temporary - there's the notion of "special object" , but for simple level 0...
      DBPointer r = (DBPointer) val;
      putDBPointer(name, r._ns, (ObjectId) r._id);
    } else if (val instanceof DBRefBase) {
      putDBRef(name, (DBRefBase) val);
    } else if (val instanceof DBSymbol) {
      putSymbol(name, (DBSymbol) val);
    } else if (val instanceof DBUndefined) {
      putUndefined(name);
    } else if (val instanceof DBTimestamp) {
      putTimestamp(name, (DBTimestamp) val);
    } else throw new IllegalArgumentException("can't serialize " + val.getClass());
  }