Matasano Crypto Challenges, Set 2

Challenge 9 Implement PKCS#7 padding

As the challenge states, “A block cipher transforms a fixed-sized block (usually 8 or 16 bytes) of plaintext into ciphertext. But we almost never want to transform a single block; we encrypt irregularly-sized messages.”

The PKCS#7 padding scheme will append the number of bytes of padding to the end of the block. I use the pwntools pack() function to pack the number of padding bytes.

Read More

NSA Cybersprint 2015

This is my first writeup, written in 2015 in Word and back-dated

Last weekend, I took to some haxxoring in the NSA Cybersprint Competition, a Capture-The-Flag that took place on a simulated corporate network infrastructure.

Here’s what it was like.

Read More