The Solitaire cryptographic algorithm was designed by Bruce Schneier at the request of Neal Stephenson for use in his novel Cryptonomicon, in which field agents use it to communicate securely without having to rely on electronics or having to carry incriminating tools. It was designed to be a manual cryptosystem calculated with an ordinary deck of playing cards. In Cryptonomicon, this algorithm was originally called Pontifex to hide the fact that it involved playing cards. One of the motivations behind Solitaire's creation is that in totalitarian environments, a deck of cards is far more affordable (and less incriminating) than a personal computer with an array of cryptological utilities. However, as Schneier warns in the appendix of Cryptonomicon, just about everyone with an interest in cryptanalysis will now know about this algorithm, so carrying a deck of cards may also be considered incriminating. Furthermore, analysis has revealed flaws in the cipher such that it is now considered insecure. Encryption and decryption This algorithm uses a standard deck of cards with 52 suited cards and two jokers which are distinguishable from each other, called the A joker and the B joker. For simplicity's sake, only two suits will be used in this example, clubs and diamonds. Each card is assigned a numerical value: the clubs will be numbered from 1 to 13 (Ace through King) and the diamonds will be numbered 14 through 26 in the same manner. The jokers will be assigned the values of 27 and 28. Thus, the jack of clubs would have the value 11, and the two of diamonds would have the value 15. (In a full deck of cards, the suits are valued in bridge order: clubs, diamonds, hearts, spades, with the suited cards numbered 1 through 52, and the jokers numbered 53 and 54.) To begin encryption or decryption, arrange the deck of cards face-up in an order previously agreed upon. The person decrypting a message must have a deck arranged in the same order as the deck used by the person who encrypted the message. How the order is initially decided upon is up to the recipients; shuffling the deck perfectly randomly is preferable, although there are many other methods. The algorithm generates a keystream, a sequence of values which are combined with the message to encrypt and decrypt it. Each value of the keystream is used to encrypt one character of the message,