challenge/echo-chamber

Echo Chamber

Crypto

by mihai

100

points

2 solves First blood: popag24

Best on a computer. This challenge connects with nc or SSH, which needs a terminal. You can still continue here if you want.

A service encrypts AES-ECB( your_input || secret ) and hands the ciphertext back to you. ECB encrypts every 16-byte block on its own, deterministically, so identical plaintext blocks give identical ciphertext blocks. Recover the secret one byte at a time. Connect with netcat; source is provided.