CTF Archive
Playable challenges from past CTF events.
Every challenge listed below is preserved here so you can replay it any time. The intended solve order varies by event; pick whichever starting point looks interesting.
Challenges
Pick a thread.
Everything has a place. Find what's been hidden in plain sight across open sources.
Miscellaneous BIKINI State: REDA recovered Royal Observer Corps watch. Convert three monitoring-post bearings, plot them on the Group Control workstation, and identify the site at the fix.
Cryptography · Multi-leg CONCORDATThree Cold War intercepts, three services — British SIGINT, American case-handling, Soviet cryptography — one week in March 1989. Three legs plus an operator, one combined flag.
Crypto · Stego The Baker Street AffairBelle Époque, summer 1908. Two intercepted documents — Holmes and Lupin — two perspectives on the same theft. Reconcile them and recover what the censors cut.
Web · Series I–IV The Sign of FourA four-part web exploitation series. Each stage unlocks the next; deduction required throughout.