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With today’s super-fast computers and the advancements in cryptography it would seem that an encrypted message dating back 70 years could easily be broken. How- ever, that proved not to be the case in this fascinating incident.
In 1982 David and Anne Martin were renovating a fireplace that had been sealed off for many years in their 17th-century house in the village of Bletchingley, England. In the chimney, the Martins discovered the remains of a carrier pigeon with a small scarlet capsule attached to its leg. The red color of the capsule marked the bird as a military carrier pigeon for the Allied Forces in World War II. Inside the capsule was a message written in code. There were 27 groups of five letters or numbers, on thin paper the size of a cigarette paper. The message read:
AOAKN HVPKD FNFJW YIDDC RQXSR DJHFP GOVFN MIAPX PABUZ WYYNP CMPNW HJRZH NLXKG MEMKK ONOIB AKEEQ WAOTA RBQRH DJOFM TPZEH LKXGH RGGHT JRZCQ FNKTQ KLDTS FQIRW AOAKN 27 1525/6
At the bottom of the coded message were two items that were not in code: “Number of Copies Sent: Two” and “Sender: Serjeant [sic] W. Stot.” Additional sets of numbers (NURP 40 TW194 and NURP 37 DK 76) probably indicated the military number of the two birds who carried the message.
The Martins contacted several British government authorities about their find, but at the time there was no interest in the bird’s message. However, in 2012, Bletchley Park, which served as the headquarters of British Intelligence code breakers during World War II and is now a museum, took an interest in the message. It turns out this message may have been ultra-secret. First, although Bletchley Park (only five miles from the Martin’s house) used carrier pigeons during World War II, none of its official messages were sent in code; they were all written in longhand. Second, messages were never carried by more than one bird. Evidently this bird’s message may have been part of a top-secret program.
In late 2012 the British government’s Government Communications Headquarters, which is responsible for code breaking, examined the encrypted message. After top government code breakers spent months using super-fast computers to attempt to break the code, they finally announced that the code could not be cracked (a few amateur sleuths have claimed to have deciphered the message, but these claims have proved to be false).
Why is it so tough to break this code? The reason is that the code was written using a one-time pad, or OTP. An OTP uses as a key a random set of letters that only the sender and recipient know. If an OTP is truly random, is used only one time, and
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Part III Cryptography 185
is kept secret by the sender and receiver, it can be virtually impossible to crack. That seems to be the case in this incident.
We may never know what message that pigeon 40TW194 was carrying. Yet, as a Government Communications Headquarters spokesperson said, “It is a tribute to the skills of the wartime code makers that, despite working under severe pressure, they devised a code that was undecipherable both then and now.”1