Cipher Hunter
Q1 capstone: break a battery of classical ciphers and document each attack.
Scenario
Twelve weeks of foundations have given you Pinter's first ten chapters, classical ciphers in Sage, and Cryptopals Set 1 in your pocket. The Q1 capstone hands you a battery of ciphertexts and asks you to break them all, with proof. Caesar, Vigenère, single-byte XOR, repeating-key XOR, and an ECB-vs-random distinguishing problem. Submit a Sage notebook with each break worked in clean prose.
Success criteria
- Recover the plaintext for each of the five challenge ciphertexts in the Q1 challenge bundle.
- For each break, document the attack: what you assumed about the key/plaintext space, what scoring function you used, what failure modes you ruled out.
- The notebook should be reproducible — anyone with Sage 10.x and your ciphertexts should be able to re-run and get the same plaintexts.
- Write a one-paragraph retrospective: which break was hardest, and what made it hard.
How this is graded
Self-graded. The marker is whether you can hand the notebook to a peer in week 53 and have them re-run it without you in the room. If you can, the work has the right shape.
How this is unlocked
This capstone unlocks at 1,500 total XP across all tracks. Q1 is structured so that completing planned chapters in philosophy, algebra, python, and sage during weeks 1–13 puts you within 100 XP of the threshold; Cryptopals weeks 6–12 cover the remainder.