About Cipherloom

A working reference for classical ciphers, written for people who want to run them rather than only read about them.

What this site is

Cipherloom is a reference collection of classical cryptography — twenty ciphers, from the Spartan staff to the Vernam pad — with three things attached to every entry: a written walkthrough, a browser tool that actually performs the cipher, and a practice challenge with a checkable answer.

We publish slowly and deliberately. New entries appear on a schedule rather than all at once, so the collection grows the way a reference work grows: a shelf at a time.

How the entries are written

Each cipher is described in the same six stages: Phenomenon (what you can see happening), Key space (how many keys exist and what that number is actually worth), Enciphering, Deciphering, Weakness (what killed it), and Practice. The stages are not decoration — the key-space discussion is where most popular treatments are vague, and vagueness is what this site is trying to avoid.

Where a cipher has a mathematical property that matters, the property is stated and the consequence is spelled out. Where a cipher's history is contested, the contest is described rather than resolved by assertion.

The bench tools

Each tool is a plain JavaScript implementation of the cipher it sits beside. It runs locally: the input never leaves your browser, and there is no server component, no analytics on the tool itself, and no storage beyond the one counter that remembers which challenges you have already solved.

If a tool and its description disagree, the description is the intent and the tool is the bug. The source is a single readable file, and corrections are welcome by email.

Who writes it

Cipherloom is an independent reference project. It carries no institutional affiliation, no university imprimatur and no claim to have discovered anything. The material is drawn from published sources — standard cryptology texts, the declassified histories of the First and Second World Wars, and the surviving technical literature of the period — and any errors are ours.

Contact: [email protected]