The Crypto Challenge Contest
Four degrees of difficulty, from pen & paper to complex mathematical problems
Solved Level 1 challenge Number Sequence
Solved Level 1 challenge How do you become a big cryptographer?
Solved Level 2 challenge Cracking SHA1-Hashed Passwords
Solved Level 1 challenge Cryptanalysis Hacking Puzzles — Part 2
Solved Level 1 challenge Number Sequence — Part 2
Solved Level 1 challenge Number Sequence
Solved Level 1 challenge Original Caesar Cipher
Solved Level 1 challenge Advent-Challenge — Part 1
Four degrees of difficulty, from pen & paper to complex mathematical problems