A very British mystery, part 5: Gavin Finds a Typo

By Gordon Rugg and Gavin Taylor

The story so far: This is a series of articles about the D’Agapeyeff Cipher, a short ciphertext that’s never been cracked. It first appeared in Alexander D’Agapeyeff’s 1939 book Codes and Ciphers. It’s a good testbed for codebreakers who have to deal with short texts. In the previous episodes, we’ve listed the codes described in the book, plus the worked examples that D’Agapeyeff used. In today’s gripping episode, we focus on a typo that Gavin found in Codes and Ciphers. It’s more exciting than it sounds, though admittedly that isn’t the most difficult challenge in the world…

Opening question: Does anyone apart from sad pedants really care about typos, and if they do, is that just a sign that they really ought to get a life?

In fact, a lot of people care a great deal about typos, in a lot of different fields, and for a lot of very good reasons, most of them involving money and the law. They’re also a serious issue if you’re applying for a job. A high proportion of organisations will reject a job application because of a single typo in the covering letter.

So why do people care so much about typos, and what does Gavin’s discovery mean for anyone interested in the D’Agapeyeff Cipher?

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A very British mystery, part 2: The D’Agapeyeff Cipher, and the first edition

By Gordon Rugg and Gavin Taylor

So why should anyone care about a short cipher that was published in a 1939 textbook? There’s a good reason, and it’s very different from the reasons for caring about the Voynich Manuscript.

With the Voynich Manuscript, there was a tantalising possibility that it might just be the key to a new approach to code making. With the D’Agapeyeff Cipher, the issue is about code breaking.

If you’re a codebreaker, then one of the things you hope for is large quantities of coded material, which give you a better chance of finding those few key points where the code is weak, so you have a chance to break in. Unfortunately for codebreakers, that doesn’t always happen. Often, you’re having to deal with a small quantity of text, but that text is important – maybe a warning of an imminent attack – so codebreakers are very keen to have better ways of getting into short coded texts.

The D’Agapeyeff Cipher is a classic test case for new ways of tackling this problem. It’s short; it was almost certainly written using one of the codes described in the book where it appears; it’s still uncracked, over seventy years later. Gordon had already had one attempt at cracking it, with his student Stephen Antrobus, using a method suggested by our colleague Dr Robert Matthews. It was a high-tech software approach that hadn’t been widely used for this type of problem before. It was well worth a try, and Stephen did an excellent job of building the software, but it didn’t crack the code. We’ll return to that story in a later episode.

So, this time round, we tried a different approach. We still started in the same place, though. Gavin bought a second-hand copy of the first edition of D’Agapeyeff’s book Codes and Ciphers.

Book collectors like first editions because the first edition of a major book can be worth a lot of money, as well as being a rare object that gives its owner more status among other book collectors.

The first edition of Codes and Ciphers isn’t like that. It’s a respectable, very ordinary hardback book from the 1930s. The reason Gavin bought a first edition was that the first edition contains the D’Agapeyeff Cipher. It’s the only edition that does.

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