This section presents a comprehensive exploration of cryptography, the art and science of secret communication. It encompasses a wide range of texts, from historical surveys of ancient ciphers to practical guides for constructing and breaking modern codes. Within these volumes, one can find detailed analyses of encryption algorithms, investigations into the techniques of cryptanalysis, and examinations of the role of cryptography in espionage and warfare. The collection also delves into the fascinating world of unsolved ciphers and the methods of concealing messages through steganography.