Update: Five encrypted radio transmissions from a New York Nazi spy
A week ago, I blogged about the encrypted messages of a World War II spy that have puzzled for decades. Thanks to my readers, today I can present news about this cryptological cold case.
Unfortunately, I have to admit one thing first: I could have written this blog article eight years ago – if I had finished reading a literature source that Cipherbrain reader Max Baertl told me about back then. However, I didn’t. Therefore, it is only today that I can present the (extremely exciting) background to an unsolved cryptogram series that I have blogged about several times. Maybe my readers can even decipher the said cryptograms with the new information.
The Köhler cryptograms
David Kahn tells in his book “Hitler’s Spies” about a spy who went by the name “Köhler”. Köhler was in New York in the forties and worked for the Abwehr, the most important German intelligence service at the time.
What’s not in “Hitler’s Spies.” During his research, David Kahn came across five coded messages originating from Köhler that reached the Abwehr in Paris in February 1944. At the time, information was being gathered in Paris about the expected Allied invasion. In 1981, Kahn published these five unsolved cryptograms in the journal “Cryptologia” (April/1981 issue). To my knowledge, this exciting crypto mystery was not subsequently appreciated in the literature. The solution remains unknown to this day.
Here are the five encrypted messages found by Kahn, which I call Köhler cryptograms (the numbers obviously stand for the length of the respective message):
An
Abwehrleitstelle Frankreich
Paris Funkstelle
Sofort vorlegen!
Betr.: Koehler
237
Ybtat mqfvo dvbis prito kecqg kokik kyiwm zuarj
alyia qtxvi vxzya szgou skiqn rbqjq nogex ezdnf
vusda zurop ixklo cmnbl grdhz swmch kupef pzlej
hbord wkkhu vthjk sfwda jepmu izvig kzlau rdrxx
mdecs spozv eeeod dlmdz nqmia pidwg xdcyy mvkso
hmmii impwq nkipa mljvm sqsbb glevn sktlq tn.
178
Eekao parwo xiavy pejux lhnjh pbqdd vdvxb mdiia
gwymn zbivm abuws dwoug djozl ylaug loaea ilihj
swjft oetad tjisn avaqn sodwb wzaxe zvoxg xpgzv
adurm shvxx xfmuq pdpvq dqwtu fryok xfvcp ydzwm
ofwfl uzfne qsslo avl.
137
tziqb lqqxs kinod mbvil sukms syarh mhzvp tvswm
ayddg rixyy omfzm ugfzz aznqe ljuyi ygwuo qmdbi
vcxgz rmzno pessh gpoyx qqlei xmaoj buugz czfdl
yzmkp gsmfm dteze oxmos.
140
dmxkb kqnvh zzeek beoop ygcca yvepv tykmt iykfl zkacv
uxiyd kruwy vnjvp xyeqp jpmfo abzpt mjtdy zvzky bjgze
vdtyd zeejw zumjp ivsna gsmzq dltxb qjqqj fnpta mqted
skijj.
229
fpoxa tijyp qrerq znqst zasnk zarvq hhsmw vlhfg pyhqc
yuirf fsgoi twgdg sbphc fkfza bpegh jzujn wtsxp ijamg
tzdto hxzdn uivww tizoc axkye lhmdn sfzjo omrhb zpith
hkisf anvdr ynhqk syrgi ltxos wabom dzwlb byava sjomn
qqszs adddu greao albon lxzgi iwpnf uzgui jgmya ksqfw
zsjl.
I have blogged about the Köher cryptograms several times. After an article I published in 2013, blog reader Max Baertl pointed out to me that Köhler could mean the spy Walter Koehler, who was in New York in the early forties. Max Baertl also named a literature source for this, namely an online article on a portal about military history, written by one David Alan Johnson.
In this source I read that the said Walter Koehler had left New York in 1941. Since the Koehler cryptograms were from 1944, that didn’t seem to fit. I therefore paid no further attention to this story.
Last week I blogged once again about the Köhler cryptograms. Afterwards, blog reader Max Baertl again pointed me to Walter Koehler and the source in question. This time I read the article all the way through and learned: Walter Koehler did indeed leave New York in 1941, but he returned there after a good year. And what’s more, the rest of Walter Koehler’s story also matched the cryptograms. The readers Ralf Bülow, Thomas Bosbach, Karo and Gerd provided further information.
With eight years delay I now suddenly knew the whole background story to the Koehler cryptograms. I do not want to withhold this from my readers.
The spy Walter Koehler
Walter Koehler, as you can read in Johnson’s article, was Dutch – despite his German last name. As an engineer, he had a good technical understanding, and he was also able to gain intelligence experience in the First World War.
Apparently, the Abwehr succeeded in recruiting Koehler as a spy in the late 1930s. He was sent to the USA with a legend attached. His main task there was to find out whether the Americans were building an atomic bomb and, if so, how far they were with it – a difficult undertaking. Initially, however, Koehler had the status of a “sleeper” – in other words, he was not active and was supposed to settle in first.
In 1941, the Abwehr unexpectedly ordered Koehler back to Germany. There were financial irregularities, and Koehler was suspected of having embezzled some of the money entrusted to him. Apparently, despite these accusations, the spy got away without punishment. Whether he provided a convincing explanation or whether he was simply needed urgently is not known.
In 1942, Koehler again traveled to the United States on behalf of the Abwehr. But this time things went differently. When he applied for a visa at the U.S. Embassy in Madrid, Koehler indicated that he had been sent as a spy by the Germans. U.S. officials, confronted with this confession, wondered but passed on the information, and eventually Koehler came to the attention of the FBI.
As Koehler had expected, the FBI now made him a double agent. He was allowed to enter the U.S., and shortly thereafter radio messages sent from New York reached the agreed contact in Hamburg. These messages were encoded with a book cipher based on a Dutch prayer book, which the Abwehr had taught Koehler before his departure.
In reality, however, the radio messages came from the FBI. Specialists there had taken over the documents from Koehler and were now impersonating him. In false espionage reports, they subsequently transmitted a mixture of banalities and false information to the Abwehr. The Abwehr replied regularly by radio and did not spare praise for the alleged spy.
Meanwhile, Koehler lived under FBI supervision in a New York hotel and lived a quiet life.
What the FBI did not know was that during his stay Koehler sent coded messages to the Abwehr in Paris in which he told the truth and provided real information. So the Abwehr knew that the FBI was behind the book cipher radio messages and that they were worth nothing. How Koehler managed to send his additional messages is not known. Perhaps he communicated with a contact via a dead drop.
The FBI did not notice Koehler’s foul play. It was not until the seventies that a U.S. journalist uncovered the hoax. I assume that Koehler had died long ago at that time wr. His exact life data are unfortunately not known to me.
Classification of the cryptograms
Let us return to the five Koehler cryptograms. These were sent to Paris. So they are reports that Walter Koehler sent without the knowledge of the FBI. They were not encrypted with the said book cipher. I discussed what methods might be used instead a week ago. Unfortunately, the Johnson article does not contain any new information on this subject. Nor do the other sources my readers mentioned provide anything in this regard.
Nevertheless, can a reader with the new information say more about the Köhler cryptograms? Maybe the messages can even be solved sometime.
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Further reading: Harold James Nicholson: Der Spion, der kodierte Grußkarten verschickte
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