The Cipher Challenge Contest
Four degrees of difficulty, from pen & paper to complex mathematical problems
Solved Level 1 challenge Turing Bombe Enigma I
Solved Level 1 challenge Letter from the Alleged Countess Julie von Ortenburg
Solved Level 1 challenge Cascading Encryption — Part 1/3
Solved Level 1 challenge Pigpen with a twist — Part 1
Solved Level 1 challenge New Year's Greetings — Part 4
Solved Level 1 challenge New Year's Greetings — Part 3
Solved Level 2 challenge ORYX Stream Cipher — Part 3 (revised)
Solved Level 2 challenge Double Column Transposition — Part 1
Four degrees of difficulty, from pen & paper to complex mathematical problems