Pontifex

From the Quicksilver Metaweb.

This is Bruce Schneier's Solitaire card deck based encryption solution

Stephensonia

Randy mentions bridge building in regards to this ecumenical nomenclature.

Counterpane

“ … Enoch Root describes a cryptosystem code-named "Pontifex" to an needy nerd named Randy Waterhouse, and later reveals that the steps of the algorithm are intended to be carried out using a deck of playing cards. These two characters go on to exchange several encrypted messages using this system. The system is called "Solitaire" (in the novel, "Pontifex" is a code name intended to temporarily conceal the fact that it employs a deck of cards) and I designed it to allow field agents to communicate securely without having to rely on electronics or having to carry incriminating tools. An agent might be in a situation where he just does not have access to a computer, or may be prosecuted if he has tools for secret communication. But a deck of cards . . . what harm is that? … ”

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Some people think they can improve on the Solitaire cipher, while still making it possible to do "by hand" (without a computer).

• Fun With Playing Cards
• Mirdek: a card cipher inspired by "Solitaire"

Other people have developed ciphers that are even more secure, but require a computer: * http://c2.com/cgi/wiki?CipherJedi