Learn how to implement a classic substitution cipher in C! This step-by-step tutorial walks you through encoding and decoding ...

The mystery serial killer would claim the lives of at least five victims and was in the midst of his protracted cat-and-mouse game with police and the media. He had at that stage attacked two young ...

1. Introduction -- 2. From Julius Caesar to simple substitution -- 3. Polyalphabetic systems -- 4. Jigsaw ciphers -- 5. Two-letter ciphers -- 6. Codes -- 7. Ciphers for spies -- 8. Producing random ...

During the Cold War, numbers stations became prolific as high-security, low-risk spy tools to send secret messages to operatives in the field. However, as early as World War I, espionage agencies were ...