publication date: Saturday, January 29, 2022 (part of Winter 2022)
clue: If this Stonehenge-loving Redditor was 2bda2998d9b0ee197da142a0447f6725, then I don't want to be 7c4f29407893c334a6cb7a87bf045c0d.
explanation: A858DE45F56D9BC9, often called just A858, was a Reddit user who created a forum of the same name in 2015 and posted encrypted messages with virtually zero explanation, attracting a large following of Internet sleuths and cryptologists who tried to make sense of it. A few messages were decoded, including one that was an ASCII map of Stonehenge, but most remain undeciphered. The original user deleted their account after a couple of years and stopped posting, but attempts to further understand the messages have continued. more…
difficulty: very hard
trivia: The clue contains the MD5 hashes for the words "wrong" and "right."