An encrypted postcard from 1962
Today it’s about a nearly 60 year old encrypted postcard. Its recipient provided it to me himself.
The year is already drawing to a close, and almost traditionally, the “Krypto im Advent” competition will soon be starting again. Students in grades 3 to 9 can win various non-cash prizes in this quiz. Those who are older can participate out of competition.
Quelle/Source: Krypto im Advent
The organizers of “Krypto im Advent” are the Karlsruhe University of Education and the Karlsruhe IT Security Initiative. The aim is to bring children and young people into contact with the topic of data security at an early age and to inspire them in a playful way. The game is realized in the form of an interactive Advent calendar and starts on December 1.
Everything else can be found on the website of the competition. I wish good luck!
The postcard from Reicholzheim
Now we come to the actual topic of the day. I have presented hundreds of encrypted postcards on Cipherbrain, and my readers have solved almost all of them. One of the few exceptions is here.
Despite all this, even this topic always has something new to offer. A few days ago, for example, Cipherbrain reader Friedrich Lehmkühler kindly sent me an encrypted postcard that is in a sense a first. It is an almost 60 years old card, which Mr. Lehmkühler received himself at that time. Normally, encrypted postcards are around 100 years old, and both sender and recipient have long since passed away.
Mr. Lehmkühler rediscovered the card while tidying up his study. He received it in 1962 from his friend and bank neighbor “Jumbo”, who went to Wertheim High School with him. The two had agreed on an encryption system for their correspondence, which they used here. Here is the card:
Quelle/Source: Friedrich Lehmkühler
No premiere is that I first had to take geography lessons to be able to classify the origin of this map. Where Dortmund, the residence of the recipient Friedrich Lehmkühler, is located, I know of course. Who wouldn’t know that in Gelsenkirchen? For the international readers, Dortmund and my current home, Gelsenkirchen, are both in the Ruhr area, in western Germany. The two cities are best known for their soccer clubs, Borussia Dortmund and Schlake 04, which share a traditional enmity.
A little more difficult to locate is Reicholzheim, where the Jumbo station resided. Reicholzheim an der Tauber, I found out, is part of Wertheim in the Main-Tauber district in Baden-Württemberg. With about 1300 inhabitants, Reicholzheim has been a recognized resort since 1968. About 30 kilometers away is the large city of Würzburg, which has already played a role on Cipherbrain.
Possible solutions
Which encryption method could have been used here? As you can read in my current book “Codebreaking: A Practical Guide“, the rather high proportion of vowels speaks for a transposition cipher. In other words, the letters of the plaintext were not replaced, but rearranged. Is my guess correct? I am sure my readers will find out.
Mr. Lehmkühler wrote me: “I made the last part on the card unrecognizable because Jumbo had simply filled up the blanks at the end of his message with X, which would unduly facilitate the already un-difficult decryption.”
So it shouldn’t be all that difficult.
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Further reading: Eine Serie von 16 verschlüsselten Postkarten
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