A Treatise On the Art of Decyphering, and of Writing in Cypher: With an Harmonic Alphabet

Thicknesse's treatise on the art of cryptography offers a fascinating glimpse into the world of 18th-century codebreaking. From simple substitution ciphers to complex polyalphabetic systems, Thicknesse provides clear and practical advice on how to create and decode secret messages. With its unique blend of history, mathematics, and espionage, this book remains a classic of the cryptologic genre.