A few weeks ago, I introduced a 1000-letter ciphertext created with a bigram substitution. Jarl Van Eycke and Louie Helm have now solved this challenge and set a new world record.

At the NSA Symposium on Cryptologic History, I gave a presentation about brute-force attacks. After a subsequent discussion with Whitfield Diffie, I realized that we need a new DES challenge. Here it is.

Last week, the biannual NSA Symposium on Cryptologic History took place in Laurel, Maryland. Here are a few pictures from this outstanding event.

The George C. Marshall Library in Lexington, VA, has a collection of documents left behind by codebreaking genius William Friedman. Today, I’m going to introduce a crypto puzzle I found there.

Outsider artist James Hampton left behind an encrypted notebook and a sculpture bearing a few encrypted labels. When I was in Washington, D.C., recently, I took a video of both.

Blog reader Christof Rieber has sent me a potential solution of a major crypto mystery: the encrypted passages of Lady Gewndolen’s diary. Is Christof’s deciphering attempt correct?

In 1914, a man sent an encrypted postcard from Kiel to Hannoversch Münden. Contrary to all other encrypted postcards I know, this one was written with a typewriter.

At the hacker conference 44CON 2019, wich took place in September in London, I gave a talk about Cold War cryptography. Here’s a professionally produced video of it.

Blog reader Norbert Biermann has recently solved a bigram substitution ciphertext consisting of 1346 letters – the shortest one ever broken. Here’s a 1000-letter ciphertext of the same kind.

During a stay in the Austrian capital of Vienna, I tried to take a look at the encrypted inscription on the cenotaph of Duke Rudolf IV. I was only partially successful.