$ ctf42

Unbreakable_Encryption

Difficulty Not rated yet

Flag format: MetaCTF{...}

There is a form of truly unbreakable encryption: the one time pad. Nobody, not Russia, not China, and not even Steve, who lives in his mom's basement and hacks governments for fun, can decrypt anything using this cipher... as long as it's used correctly. In this scheme, a truly random string as long as the plaintext is chosen, and the ciphertext is computed as the bitwise XOR of the plaintext and the key. However, if the key is reused even once, it can be cracked. We've intercepted some messages between some criminals, and we're hoping you could crack the one time pad they used. We're pretty sure they reused it, so you should be able to crack it...

Ciphertext 1: 4fd098298db95b7f1bc205b0a6d8ac15f1f821d72fbfa979d1c2148a24feaafdee8d3108e8ce29c3ce1291

Plaintext 1: hey let's rob the bank at midnight tonight!

Ciphertext 2: 41d9806ec1b55c78258703be87ac9e06edb7369133b1d67ac0960d8632cfb7f2e7974e0ff3c536c1871b

Writeups

Official

No official writeup linked.

Community

Log in to add a community writeup.