The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography is a book by Simon Singh, published in 1999 by Fourth Estate and Doubleday.

[1] The Code Book covers diverse historical topics including the Man in the Iron Mask, Arabic cryptography, Charles Babbage, the mechanisation of cryptography, the Enigma machine, and the decryption of Linear B and other ancient writing systems.

[2][3] Later sections cover the development of public-key cryptography.

Some of this material is based on interviews with participants, including persons who worked in secret at GCHQ.

[4] The book is not footnoted but has a "Further Reading" section at the end, organized by chapter.