The Cipher Challenge Contest
Four degrees of difficulty, from pen & paper to complex mathematical problems
Solved Level 1 challenge Number Sequence
Solved Level 1 challenge Number Sequence
Solved Level 1 challenge Number Sequence — Part 6
Solved Level 1 challenge Number Sequence — Part 5
Solved Level 3 challenge CMEA 2
Solved Level 2 challenge Factorization Cipher — Part 2
Solved Level 2 challenge Unconcealed RSA messages
Solved Level 1 challenge An Invisible Message
Four degrees of difficulty, from pen & paper to complex mathematical problems