The Cipher Challenge Contest
Four degrees of difficulty, from pen & paper to complex mathematical problems
Solved Level 1 challenge Number Sequence — Part 7
Solved Level 1 challenge Modular Sequences
Solved Level 1 challenge ECDH-Key Exchange for Beginners
Solved Level 1 challenge Zodiac Cipher
Solved Level 2 challenge The SIGABA Challenge — Part 1
Solved Level 1 challenge A hidden word
Solved Level 1 challenge Image Noise
Solved Level 1 challenge Letter to the Templars — Part 2
Four degrees of difficulty, from pen & paper to complex mathematical problems