<p>The Alan Turing Cryptography Competition is an online puzzle series run by the Department of Mathematics at the University of Manchester. Students work through a six-chapter detective story, where each chapter contains a cipher or cryptographic puzzle drawing on logic, frequency analysis, and elementary number theory.</p><ul><li>Target audience is secondary school students up to Year 11 (UK) and equivalent, but the puzzles are open for anyone worldwide to attempt</li><li>Runs annually, typically opening in January with chapters released episodically through to March</li><li>No registration fee; solutions to past editions are published in the archive for practice</li><li>Has a sister competition, MathsBombe, aimed at older A-level students</li></ul><p>Past puzzles and solutions are available in the competition archive and can be attempted any time before a new edition opens.</p>