Encrypted newspaper advertisements were very popular in the 19th century. The ones I am going to introduce today are much younger. They were published in the 1980s.
Edgar Allan Poe once asked the readers of a magazine to send him encrypted messages. He could break all of them, except two.
Codebreaker genius William Friedman needed 15 minutes to break this cryptogram. His wife Elizebeth, an outstanding cryptanalyst in her own right, needed 17 minutes. How fast can you solve it?
In WW2 German spy Wulf Schmidt used a simple encryption method based on a crossword puzzle.
In the British National Archives I found a small codebook from World War I. Apparently, it contains a German code that was reverse-engineered by British codebreakers. Many details about the origin of this codebook are unclear.
The Handycipher is an encryption algorithm that doesn’t require a computer program or a machine. But is it secure?