You can make a message secret in countless different ways. One common way is to use a substitution cipher, in which one letter is substituted for another. Another is to employ a transposition cipher, ...

Introduction to ciphers and substitution. Alice and Bob and Carl and Julius: terminology and Caesar Cipher ; The key to the matter: generalizing the Caesar Cipher ; Multiplicative ciphers ; Affine ...

Hannah handed me a piece of paper with the following string of letters. “Each letter stands for another one,” said Hannah. “Ooh, a substitution cipher!” I thought. But I was stumped. “Is this just one ...

In 1854, Sir Charles Wheatstone invented the cipher known as "Playfair," named for his friend Lyon Playfair, first Baron Playfair of St. Andrews, who popularized and promoted the cipher. Its ...

Ars' own Julian Sanchez has deciphered a code embedded into the TV show Fringe. Bad Robot, the production company that created the Fox TV show, has been integrating puzzles and easter eggs into shows ...