Just like every end of year, I am awarding the Golden Alice for outstanding achievements in the field of crypto history and codebreaking.


In May 2014 the NSA published four crypto challenges via Twitter. To my knowledge, the fourth one is still unsolved.


In 1916 an unknown man robbed a ticket counter at the train station of Lima, Ohio. According to a local newspaper he left behind an encrypted message, the purpose of which is unknown. The message has never been deciphered.


20 years after the last message of the infamous Zodiac Killer an unknown person sent a Zodiac-style postcard to a California newspaper. As far as I know, it has never been deciphered.


Today’s blog post is not about an unsolved cryptogram. Instead, I need the help from my readers to solve a mathematical problem. The solution might be helpful to break encryptions.


Three encrypted texts left behind by Nobel Prize winner Richard Feynman are probably the most famous crypto mystery I have never blogged about before. Today, this is going to change.


Crypto puzzle games in the advent time have a long tradition. Here are two nice ones of this year’s season.


The Reddit discussion group /r/codes is a forum for cryptographic questions of all kinds. Occasionally, interesting unsolved cryptograms can be found there.


The fifth episode of HISTORY’s Zodiac Killer documentary revealed an alleged solution of the infamous Z340 cryptogram. Does it make sense?


Four episodes of the Zodiac Killer documentary on HISTORY have aired now. The fourth one ended with Craig Bauer saying that he has broken Z340. Will episode 5 tell us the solution?