Mar
20

0CTF 2017 Quals – Zer0llvm

Talent Yang loves to customize his own obfuscator. Unfortunately, he lost his seed when he was watching Arsenal’s UEFA game. What a sad day! His team and his seed were lost together. To save him, could you help him to get back his seed? We can not save the game, but we may be able… Continue reading »

Mar
20

0CTF 2017 Quals – OneTimePad 1 and 2

I swear that the safest cryptosystem is used to encrypt the secret! oneTimePad.zip Well, maybe the previous one is too simple. So I designed the ultimate one to protect the top secret! oneTimePad2.zip Summary: breaking a linear and an LCG-style exponential PRNGs.

May
03

Google CTF – Woodman (Crypto 100)

How honest are you? Running here Summary: breaking a weak PRNG

Oct
30

Hack.lu 2010 CTF Challenge #5 Writeup

Captain Redbeard’s Battleships (500) While pirating-out a bit, you run into Captain Redbeard and his armada of ghost ships. source1, source2 pirates.fluxfingers.net 2204 /tcp. It is a Battleships game. We have to win Cpt. Redbeard 3 times in a row, to get the flag. First time he shots every 3 ships from 5, than 4… Continue reading »