HackIM - Breaking Bad Key Exchange - Crypto Challenge

HackIM time again. This year seemed slightly better organized than last year. Some nice challenges. I don’t think this challenge was worth 350 points but I’ll document my solution anyway in sort of a “what not to do” when making a crypto challenge. Here’s the clue including the image they gave as a description:

Sharif CTF 2016 - LSB Oracle - Crypto Challenge

Cool challenge that I’ve wanted a reason to solve for a while because I always miss these in CTFs of the past (Tokyo Westerners CTF had a good, harder one previously).

SECCON 2016 Quals - Memory Analysis - Forensics Challenge

Very unimaginativly entitled challenge with a lot of hints should have been pretty straightforward. And yeah it was pretty much so a very quick writeup this time. The clue was:

hack.lu CTF 2016 - Cornelius1 - Crypto Challenge

Wasn’t able to login to this CTF until about 3 hours before it was over. So we got what we could solved in that time. This challenge was fun and I’ll go through my solution very fast. Firstly here’s the clue:

H4ckIT CTF 2016: Interceptor - Crypto Challenge

Quick writeup for this one so I remember it for later. Although this CTF ran all week, we sorta need that, since it took about a day for the challenge GUI to load every time you clicked something. Ugh. Anyways, this was an interesting challenge because it appeared very simple but I wasn’t immediately solving it using quick tricks. Anyway lets look at the clue: