Welcome to our Challenge!

You are an intelligence officer and your mission, should you choose to accept it, is to make sense of a transmission that we captured on our spy satellites. In order to download the transmission dump, you must connect to the TCP server at challenge.airtime.com:2323

In order to authenticate with the server, the client must perform a handshake:

  1. Upon connection, the server will send you a handshake packet: "WHORU:<challenge number>\n" without quotes, encoded in UTF-8.
  2. You must then send an identification packet: "IAM:<challenge number>:<user email address>:at\n" without quotes, encoded in UTF-8.
  3. If the identification was successful, the server will respond with a success packet containing your identification code. "SUCCESS:<identification code>\n" without quotes, encoded in UTF-8.

Once the server sends the success packet, it will begin sending the entire satellite dump over the socket.

In order to help understand the transmission, we have stolen an excerpt of a secret document that may help.

Each packet has the following structure:
0 4 8 12
|SEQ|CHK|LEN|…LEN bytes of raw Linear PCM |

CHK (Checksum)
The 32-bit checksum is calculated by XOR'ing each 32-bit chunk of
the 4 byte big-endian sequence number(SEQ) and data. If LEN is
not a multiple of 4, the byte 0xAB shall be used in place of the
missing bytes only for the purpose of calculating the checksum.


When you're done, send us your findings along with your source code. Good luck!