The Cipher Challenge Contest
Four degrees of difficulty, from pen & paper to complex mathematical problems
Solved Level 1 challenge Factorization Cipher — Part 1
Solved Level 1 challenge Affine Codes / Modulo Arithmetic with N / Extended Euclid
Solved Level 1 challenge Letter to the Templars — Part 2
Solved Level 1 challenge Letter to the Templars — Part 1
Solved Level 1 challenge A hidden word
Solved Level 1 challenge Beaver Code
Solved Level 1 challenge Caesar Encryption
Solved Level 1 challenge Original Caesar Cipher
Four degrees of difficulty, from pen & paper to complex mathematical problems