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 ...

It’s been a couple of Math Mondays since we last looked at columnar transposition ciphers, so let’s jump back in. In the It’s been a couple of Math Mondays since we last looked at columnar ...

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, ...

I hope you enjoyed Ed’s guest posts on NP-complete problems on TV the last couple of Mondays. It’s always great to hear from others on math that they are thinking about. This week it’s me again, and ...

Today we’re going to talk about how to keep information secret, and this isn’t a new goal. We’re going to walk you through some common encryption techniques such as the Advanced Encryption Standard ...

Since ancient times, people have relied on cryptography, the art of writing and solving coded messages, to keep their secrets secure. In the fifth century, enciphered messages were inscribed on ...

Cryptographic researchers have finally cracked a 51-year-old code left by the Zodiac, a serial killer who terrorized Northern California in the late 1960s and early 1970s. Much of the work of cracking ...