In 1873, an unknown person published two encrypted advertisements in the Daily Telegraph. Can a reader break these cryptograms?

At the NSA Symposium on Cryptologic History, I will give a presentation about brute-force attacks. There’s one thing I still haven’t figured out: when was the first brute-force described or carried out?

In 1916, a man living in Aschersleben, Germany, received an encrypted postcard. Can a reader decipher it?

Sometimes, deciphering a cryptogram is easier than reading the deciphered message. Here are two plaintexts I have difficulties to understand.

In the end credits of the 2010 movie “Fair Game” some letters are marked. Do they spell out an encrypted message? Nine years after the release of the film, this question is still unanswered.

The straddle checkerboard was an important part of many Cold War ciphers. Can a reader decipher three ciphertexts I created with this encryption method?

A picture of Arnold Schwarzenegger, taken at the set of “Conan the Barbarian”, shows an encrypted (?) text. Can a reader decipher it?

In the early 1970s, cryptographers in the USA and in East Germany developed two suprisingly similar encryption methods. Did one party steal from the other? Or was a useful concept invented twice?

The Science Museum in London is hosting an exhibition about secrets and ciphers. The exhibits include a quilt bearing encrypted messages.

Today I’m going to present a 28 letter message that has been encrypted with a Playfair cipher. To my knowledge, such a short Playfair cryptogram has never been solved before.