Cobol OTP Category: Crypto Author: midao Level: easy Solves: 104 Thanks to R. who actually flagged it :) Description To save the future you have to look at the past. Someone from the inside sent you an access code to a bank account with a lot of money. Can you handle the past and decrypt the code to save the future? Attached file A zip is provided with: otp.cob: a program in Cobol out 1 2 Enter your message to encrypt: ���y;dhu��F�]UjhC��-�1T`h&��F�1*T{_���p02J Understanding the Cobol program We understand the Cobol program is performing XOR encryption using a key provided in a keyfille.

This was a different type of challenge, in between regular Escape Rooms/ Geo-caching and CTF. 11 different challenges were scattered nearby the CTF room, and you needed to solve at least 10 of these challenges to be able to recover a code to unlock a safe where you’d find a flag for the Exploit Quest. The challenges weren’t too difficult, but I found this rather long and was happy to complete the task with @IdleWog (mushd00m team).