Eli Sohl

Hello and welcome to NCC Group’s Cryptopals guided tour! This post is the second in a series of eight installments (previously) covering the solutions to the Cryptopals Crypto Challenges. For those who don’t know, Cryptopals is a series of eight sets of challenges covering common cryptographic constructs and common attacks…

Hello and welcome to NCC Group’s Cryptopals guided tour! This post is the first in a series of eight installments covering the solutions to the Cryptopals Crypto Challenges. These have been a long time coming, and we’re excited to finally start bringing them to you. For those who don’t know,…

This is a write-up of the classic padding oracle attack on CBC-mode block ciphers. If you’ve done the Cryptopals cryptography challenges, you’ll remember it as challenge 17. This is a famous and elegant attack. With it, we will see how even a small data leak (in this case, the presence…