The Cipher Challenge Contest
Four degrees of difficulty, from pen & paper to complex mathematical problems
Solved Level 1 challenge New Year's Greetings — Part 2
Solved Level 1 challenge Bigram Substitution – Part 1 (Tutorial)
Solved Level 1 challenge Assembly Point – Part 1
Solved Level 1 challenge Number Sequence — Part 10
Solved Level 1 challenge Factorization Cipher — Part 1
Solved Level 1 challenge Double Columnar Transposition
Solved Level 1 challenge Affine Codes / Modulo Arithmetic with N / Extended Euclid
Solved Level 1 challenge ADFGVX — Part 1
Four degrees of difficulty, from pen & paper to complex mathematical problems