The Cipher Challenge Contest
Four degrees of difficulty, from pen & paper to complex mathematical problems
Solved Level 1 challenge The Last Note
Solved Level 2 challenge Broadcasting and low exponent — RSA Attack
Solved Level 1 challenge Snow White and the seven dwarfs
Solved Level 1 challenge Number Sequence
Solved Level 1 challenge One-Time Pad with Flaws
Solved Level 1 challenge Hill Cipher with Sudoku Key
Solved Level 2 challenge Lattice Part 1
Solved Level 1 challenge Nils away on travel
Four degrees of difficulty, from pen & paper to complex mathematical problems