How the CIA’s Kryptos Sculpture Gave Up Its Final Secret

The 35-year-old saga of Kryptos, an enigmatic sculpture containing four encrypted messages outside the CIA headquarters, just ...
insider.si.edu

The mathematics of secrets : cryptography from Caesar ciphers to digital encryption / Joshua Holden

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 ...
Scientific American

How the World’s Most Famous Code Was Cracked

How does one crack the world’s most famous code? The breakthroughs on Kryptos provide a guided tour through the cat and mouse game between code makers and code breakers that has defined information ...
PBS

The Double Playfair Cipher

The Double Playfair is an extension of the Playfair to use two separate keys and to encipher each pair of letters twice. The German police made the mistake in late 1941 of switching from the rather ...