The keys are correct as stated, but instead of numbering duplicate letters from left to right, Agent Madeleine numbered them from right to left. You may want to complete the decryption yourself before ...

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 ...

A single leaked hint exposed the CIA’s most puzzling code. But dozens of the world’s toughest ciphers are still waiting to be solved.

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 ...

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 ...