The tale is told that centuries ago, Grand Vizier Sissa Ben Dahir invented a new pleasure for his king, Shirham of India, the game of chess. Delighted, the king asked this vizier to name his reward. Sissa Ben Dahir was not just inventive, but mischievous. He archly requested a trifle, a mere portion of wheat: [...]

Alice has two secret documents, X and Y. She agrees to let Bob choose and receive one—but only one. Bob, however, doesn’t want Alice to know which document he has selected.  So they engage in a exchange of the utmost delicacy…

RSA is a cryptographic system named after the inventors, Rivest, Shamir, and Adleman, who conceived it in 1977. It is the technical axis around which Tetraktys revolves. In the novel, a cult of Pythagoreans appears to have broken this cryptosystem, spreading alarm within the NSA (National Security Agency)—at least among those in the Agency who [...]