His ciphers would begin with “I” and include the word “kill.” Moreover, the Zodiac Killer used a homophonic substitution cipher to encode a plaintext message. But then, the Zodiac Killer ...

The Zodiac remains one of the most mysterious serial killers in U.S. history, active at the turn of the 1960s and 1970s. He is credited with murdering 37 people but was never caught. Investigators ...

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.