The Cipher Challenge Contest
Four degrees of difficulty, from pen & paper to complex mathematical problems
Solved Level 1 challenge Number Sequence — Part 2
Solved Level 1 challenge Number Sequence
Solved Level 1 challenge Beaver Code
Solved Level 2 challenge Alice's Birthday Party (Part 2)
Solved Level 2 challenge Merkle-Hellman Knapsack Challenge — Part 2
Solved Level 2 challenge A Cloaked Substitution Cipher — Part 2
Solved Level 2 challenge Not-so-Secret Message from Malawi — Part I (RSA)
Solved Level 2 challenge A Cloaked Substitution Cipher — Part 1
Four degrees of difficulty, from pen & paper to complex mathematical problems