After 51 years, a group of three hobbyist cryptographers is claiming to have cracked one of the most infamous ciphers created by the infamous Zodiac killer. In a video posted to YouTube, David Oranchak explains the processes he and two others went through to crack “The 340” cipher, which is made up of 340 symbols—some of which are English characters and others of which are cryptic marks.
“Oh my god, so this is a big one. We have a solution for the 340, and it’s real,” Oranchak says in the video. Well-known cryptographers who analyzed the video and accompanying blog posts for Motherboard said that the group’s solution at least seems plausible. Oranchak told Motherboard he has been working on solving the 340 for more than a decade.