Applied Cryptography
Break real schemes the way attackers do — by what they leak, not the maths.
- Estimated time
- 1 hour
- Rooms
- 2 rooms
- Points
- 375 pts
- Enrolled
- Be the first to enroll
About this path
Cryptography fails in practice far more often than it fails in theory. This path is about applied breaks: recognising weak constructions, exploiting side-channels and oracles, and recovering or forging secrets without ever holding the key. You will go from classic keystream reuse to a full padding-oracle forgery, building the attacker mindset that 'a perfect cipher used carelessly is still broken'.
Who should start here
Learners who know a little crypto theory and want to see how real systems get broken — CTF players, pentesters, and curious developers.
Prerequisites
Comfort with XOR, hex/base64, and bytes, plus basic block-cipher ideas (CBC, PKCS#7). Python for scripting. No heavy mathematics.
What you will be able to do
- Exploit keystream / key reuse to recover plaintext
- Reason about CBC mode and PKCS#7 padding
- Build a padding oracle and recover a block's intermediate value
- Forge a chosen plaintext with CBC-R and defeat an auth check
- Adopt the 'broken by what it leaks' attacker mindset
Curriculum
Module 1 — Keystream & encoding0 of 1 rooms complete
When the same secret is used twice.
Module 2 — Oracle attacks0 of 1 rooms complete
Let the server decrypt for you.