All Writeups

Comprehensive collection of CTF challenges, solutions, and insights.

2026-03-01 Crypto Easy

DEADROP Crypto 1 - INTERCEPTED TRANSMISSION 774

Decrypting a Vigenère-ciphered field report by recovering the key from an acrostic hidden in the challenge description, first letter of each sentence spells PIGEON.

vigenere classical-cipher acrostic crib-drag

2026-02-24 Crypto Hard

WHAMazon! Crypto 6 - Manifest Collision

Exploiting XOR keystream reuse across two ciphertexts, cancelling the key, identifying newline-heavy P2 via single-byte XOR brute force, then recovering the full key via known-plaintext crib drag to extract the flag.

xor two-time-pad crib-drag known-plaintext

2026-02-23 Crypto Easy

WHAMazon! Crypto 1 - Workers are Exhausted

Identifying hex-encoded XOR ciphertext and brute-forcing the single-byte key using a known-plaintext crib from the flag format.

xor hex brute-force known-plaintext