The Cipher Challenge Contest
Four degrees of difficulty, from pen & paper to complex mathematical problems
Solved Level 2 challenge Alberti Challenge — Part 2
Solved Level 1 challenge Reserve Hand Procedure — Part 1
Solved Level 1 challenge Letter to the Templars — Part 2
Solved Level 1 challenge Letter to the Templars — Part 1
Solved Level 2 challenge Lunchtime Attack on the Fully Homomorphic Encryption Scheme
Solved Level 1 challenge M-138 — Part 1
Solved Level 2 challenge Pigpen with a twist — Part 2
Solved Level 2 challenge Hill Cipher
Four degrees of difficulty, from pen & paper to complex mathematical problems