All rooms Sign in
CryptographyLesson + challenge Live machinePremium

The Padded Room

The lock is perfect. The door tells you too much.

A perfect cipher, broken by one leaked bit. Use an AES-CBC padding oracle to recover a block's intermediate value and forge an 'admin' token (CBC-R) — no key required — then open the vault and read the flag.

Difficulty
Medium
Estimated time
60 min
Points
300 pts
Completions
Completed by 1 player
Authors
By Cyber Academy 4 U
Create a free account to startSign in

What you will learn

  • Explain why revealing a padding error breaks CBC confidentiality
  • Recover a ciphertext block's intermediate value with a padding oracle
  • Use the oracle as an encryption primitive (CBC-R) to forge a chosen plaintext
  • Defeat an authorization check without ever recovering the key

What is inside

  1. Task 1 · The Padded Room1 question

Sign in to read the tasks, start the machine and answer the questions.