The FBI has recently declassified crypto-related files from the 1940s. These files contain a number of amusing stories.
Gary Klivans, expert on gang and prison codes, has provided me information on an interesting case. It is about an encrypted letter sent by a prison inmate.
Little was known about the ciphers of the Unabomber, a highly intelligent serial killer, until the FBI published a detailed description last year. Here’s a summary.