# The Top 50 unsolved encrypted messages: 15. The Rilke cryptogram

During the Second World War, an unknown person stuck sheets with seemingly random letter sequences into a book. The meaning of these letters is unknown.

Two years ago, blog reader Dr. Karsten Hansky provided me with an extremely interesting encryption puzzle. In a copy of the book Rainer Maria Rilke by Gert Buchheit …

… somebody has pasted sheets filled with seemingly meaningless typed letter sequences. Virtually every free space in the book is used for this purpose, but no book text has been pasted over. The first page looks like this (scans of all pages are available here):

Apparently, the letters were printed with a hectograph (until about 1990 hectography was the cheapest printing method). The book Rainer Maria Rilke by Gert Buchheit was originally published in 1928. The edition we deal with here is a reprint from 1942. According to the page shown above, it is a “unique special edition published by the [German] headquarters of the war front bookstores in Paris.”

I have blogged about this mystery a few times before (in German). So far, nobody has found an explanation for these letter sequences. In my opinion, there are three plausible explanations.

### 1) An encrypted message?

Of course, the Rilke cryptogram could be an encrypted message (otherwise it would not be interesting for this blog).

Pros: The Rilke cryptogram consists of four-letter groups. This is the way the German navy noted radio messages in the Second World War.

Cons : The Rilke cryptogram contains numerous patterns, like letters in the same order as on the keyboard, repetitions, and symmetries. In addition, there are almost no letter duplications, and nearly every letter group contains four different letters. All this would be very unusual for an encrypted text.

### 2) A key?

Is the Rilke cryptogram a cryptographic key that was meant to be used for a one-time pad or another cipher?

Pros: It is certainly possible to use these letters as a key. In addition, hiding a key (in this case in a book) makes sense.

Cons: The Rilke cryptogram was produced with a hectograph. This technique was rarely used for keys, as hectography only makes sense, if several copies of the original sheet are required. In addition, I have never seen a one time pad key consisting of letters and numbers, including German umlauts.

### 3) Exercise material?

Is the Rilke cryptogram just a meaningless sequence of letters and numbers made for soldiers to practice the Morse code or another writing or transmission technique?

Pros: Hectography was a very common technique for printing exercise sheets for students. The strange repetitions and patterns would not bother, if the letters and numbers were only practicing  material. It is easy to imagine that a soldier taking part in Morse lessons would have pasted an exercise sheet into an unobtrusive book to hide it from his fellows (it was quite common that soldiers had to keep their activities secret even from their fellow soldiers).

Cons: It is unusual that a text made for practicing the Morse code or something  similar consists of meaningless gibberish. Why not use a standard text? In addition, the Rilke cryptogram contains the German letters “ä”, “ö” and “ü”. There are Morse equivalents of these characters, but they are rarely used in the military.

In my view, the Rilke cryptogram is neither a ciphertext nor a key. There is simply no encryption method I have ever encountered that uses keys like this one or produces ciphertexts like this one. In addition, I have never seen hectography being used for a key or a ciphertext.

So, in the end, the exercise text hypothesis is the one I like best. Using a hectograph for producing excercise sheets was very common, even in my school days in the 1980s. I can easily imagine that a WW2 soldier, who had to learn the Morse code or some other writing technique, pasted an excercise sheet into a book he carried with him. All this makes sense, but, of course, there no proof for this hypothesis. Does a reader have a better explanation? Any suggestions are welcome.

Further reading: My visit at the Cheltenham Listening Stones

## Subscribe to Blog via Email

Gib Deine E-Mail-Adresse an, um diesen Blog zu abonnieren und Benachrichtigungen über neue Beiträge via E-Mail zu erhalten.

## Kommentare (10)

1. #1 m
10. Januar 2018

Abo

2. #2 Gerry and Andrea
10. Januar 2018

There is an interesting information on familysearch.org regarding Heinz-Hermann Klaus: He is listed as immigrant (21 years old, occupation furrier) to the United States in 1933, with his last residence listed as Plauen, Germany. Did he return to Germany before or during WW2? Far shot – a double agent in SigInt?

3. #3 Ralf Bülow
10. Januar 2018

Note that Gert Buchheit – the author of the Rilke book – later worked for the Bundesnachrichtendienst, viz. http://www.spiegel.de/spiegel/print/d-90535606.html

4. #4 Thomas
10. Januar 2018

Klaus:
Zu der Übungsmaterial-These: Hast Du schon einmal beim Bundesarchiv-Militärarchiv in Freiburg nachgefragt, ob die Buchstaben-/Zifferngruppen mit dem Übungsmaterial für den Morsegebeunterricht übereinstimmt? Hierüber gibt es dort eine Heeres-Druckvorschrift 421/8c von 1943 mit der Signatur BArch, RHD 4/1423: https://www.deutsche-digitale-bibliothek.de//item/LF3HKWEIBNU5EREG5CI5UZVB36QYAYZO, leider kein online-Digitalisat verfügbar. (Möglicherweise sind, um die Sache schwieriger zu machen, für die Ausbildung willkürliche Zeichengruppen einschließlich Umlauten verwendet worden.)

5. #5 Karsten Hansky
10. Januar 2018

@Gerry and Andrea
Thats interesting news.

Hermann Klaus was served in the FAK624 (Fernaufklörungskompanie 624) in the rank of a sergeant. He entered this unit on 14th April 1943. The FAK624 was a sigint unit in France.

I have his address in Plauen and the name of his wife Hildegar but my further research let to nothing The house still exists but no relatives and no public records.

He most probably survived the war. I bought this book from a book dealer in Hamburg who had no information where it came from.

Hermann Klaus was born on 25th December 1911 in Plauen so the information which you found seems to be correct. When he left Germany in 1933 it was certainly due to the Nazis. So it is surprising that he served in the German army 10 years later!

> Far shot – a double agent in SigInt?
Maybe not so far?

Regards

Karsten

6. #6 Karsten Hansky
10. Januar 2018

@Gerry and Andrea
Thats interesting news.

Hermann Klaus served in the FAK624 (Fernaufklörungskompanie 624) in the rank of a sergeant. He entered this unit on 14th April 1943. The FAK624 was a sigint unit in France.

I have his address in Plauen and the name of his wife Hildegar but my further research let to nothing The house still exists but no relatives and no public records.

He most probably survived the war. I bought this book from a book dealer in Hamburg who had no information where it came from.

Hermann Klaus was born on 25th December 1911 in Plauen so the information which you found seems to be correct. When he left Germany in 1933 it was certainly due to the Nazis. So it is surprising that he served in the German army 10 years later!

> Far shot – a double agent in SigInt?
Maybe not so far?

Regards

Karsten

Kalmar, Sweden
10. Januar 2018

“Cons: It is unusual that a text made for practicing the Morse code or something similar consists of meaningless gibberish.”
On the contrary. When I was taught morse, most exercises were made up of gibberish text – very similar looking to the Rilke texts – since that was what we were expected to transmit and receive later on (I can’t remember ever sending or receiving any messages in plain language after finishing Communications Training, back in my service days).

8. #8 Thomas
10. Januar 2018

Exactly, that’s why looking for training material of the Wehrmacht (e.g. the link in #4) might be worth a try.

9. #9 Gerd
10. Januar 2018

some more points:
1. Code used for training of morse transmissions usually is random, gibberish text. This is to prevent hearing errors to be compensated by guessing of words, and this is extremely important for training purposes.
2. Sergeant Klaus was in FAK 624, which was part of the army (Heer). As far as I have noticed – also from enigma traffic published in this blog – the army always used five letter groups, whereas only the navy used four letter groups. Can anyone confirm this?
3. Also known from enigma traffic: in the german military, no umlauts were used in morse code. Umlauts were transcribed as ae, oe, ue. So why include them in a training text?

Gerd

10. #10 Charlotte Auer
11. Januar 2018

Von solchen Chriffren habe ich ja so ziemlich genau Null Ahnung, aber eine Idee ist mir doch gekommen.

Was, wenn die Buchstaben einschließlich der Umlaute nur Blender sind und lediglich die Ziffern eine Bedeutung haben? Das würde evtl. die merkwürdigen Buchstabenfolgen ebenso wie die Umlaute durchaus plausibel erklären, da sie eben nur Füllmaterial ohne Nachrichtenwert sind. Es wäre also womöglich eine Buch-Chiffre mit dem damals in bestimmten Kreisen ja recht unauffälligen und weit verbreiteten Text als Schlüssel. Macht das Sinn?

Um das heraus zu finden, müsste man wohl das gesamte Buch vor sich haben.