In war efficient
and secure means of communication are vital for any undertaking. Without the
ability to communicate quickly with his underlying units a general will lose
control of a battle. Without the ability to control faraway units a military
command will see its forces attacked and destroyed piecemeal.
WWII historians
tend to focus too much on tanks and aircraft while at the same time neglecting the
huge effort made by the warring nations to build up modern communication networks.
During the
war the US Signal Corps built up a modern worldwide communications network for
US military and diplomatic authorities. This network was called ACAN (Army
Command and Administrative Network).
ACAN linked
centers in London, Hawaii, New Delhi, Karachi, Chungking, Algiers, Cairo, Basra,
Casablanca, Accra, Asmara and other areas with the War Department Signal Center
(codename ‘WAR’) in Washington.
For the rapid
transmission of messages several types of equipment were used. Initially hand
Morse and Boehme (rapid Morse) equipment, then radiotype and finally the modern
radio-teletype (enciphered).
It was thanks
to these networks that the Allied commanders could efficiently command their
forces all over the globe.
German
interception of ACAN networks
These
networks were monitored by the German signal intelligence agencies and both
plaintext and cipher traffic was intercepted.
Due to the
very large number of messages passing on these networks some important
information was always available in plaintext transmissions. In addition some
of the hand codes used could be ‘broken’.
It also seems
that the Germans repeated their ‘Russian Fish ‘success by building a special
device that automatically intercepted and printed the teleprinter traffic.
There are few
details on this affair but I’ve tried to collate all the available information.
From postwar
interrogations it seems that at least 4 agencies intercepted and evaluated this
traffic.
1). The Army
Ordnance, Development and Testing Group, Signal Branch Group IV C - Wa Pruef 7/IV C at an experimental
station in Staats.
2). The
Signal intelligence Agency of the Supreme Command of the Armed Forces - OKW/Chi.
3). The
Luftwaffe Signal Intelligence agency’s LN
Abt 350 Referat B in Asnieres,
Paris and later Munich-Oberhaching and a special unit operating from Berlin-Schoenfeld.
4). The Army
Signal Intelligence agency - OKH/GdNA from
bases in Norway and Euskirchen, Germany.
Wa Pruef
7/IV effort:
The Wa Pruef
7/IV C department has been mentioned before in connection with the ‘Russian
Fish’ equipment. It was headed by Bau Rat Kierkhoff and according to a
postwar interrogation there were about 5-6 engineers, 7-8 other men and 60 odd
Nachrichtenhelferinnen (women helpers).
Report FMS
P-038 ‘German Radio Intelligence’ says that the Staats station intercepted
Russian, British, American and French radio-teletype systems.
This traffic
was passed on to OKW/Chi and OKH/GdNA for analysis and evaluation.
OKW/Chi
effort:
Wilhelm
Flicke a member of OKW/Chi mentions in his book ‘War secrets in the Ether’ the
interception of US overseas traffic.
In pages
295-6 he says:
Of the "big fry" the USA
provided its enemies most amply with information. Among other things a special
radio network had been set up in 1942 which covered the entire globe. This was
the "WVNA-net" (named from the call-sign of the station in Karachi,
India, which was the first one heard.) Most of the exchange of messages could
be read currently; it afforded information on American military measures in the
Far, Middle, and Near East and in Africa. The following survey shows the extent
of the network in November 1942:
WVNA -net
call sign, location,
cover name and interpretation
Washington agwar = Adjutant General, War Department
milid = Attache
crypto = Secret
communications service
victor = Proper
name, (head of "crypto") "Signatures: Arnold, Cambela,
Groninger, Kroner, Loughry, Marshall, Ohnstaed, Osborn, Reybold, Sommervell,
Strong, Ulio.
wvna Karachi (India) speck =
proper name
Signatures : Jordan
(Vice-Consul) ,Wheeler (General and head of the USA military mission).
wvmt Basra (Iraq) amsir = American military section Iraq
Signature
: Connoly (Vice-Consul)
wvnv Cairo (Egypt) amsme = American military Section Middle East
wvnt Asmara (Formerly Italian-East Africa) amseg
= American military Section
Signature:Hodges
wvmy Teheran (Iran) amrus = American military Section Russia
Signature: Ondrick ( Mil.Att.)
S9x Delhi (India) aquila = Cover name for
American air forces.
ammdel = American military mission Delhi
amobsin = American military
observer India
Signatures: Tiger, Speck (only there for a short time)
nekci Chungking (China) ammisca
= American military Section
Karachi Office in Chungking
amilat = American military attaché
Signature : Stilwell ( General and
Commander of US Forces in China)
Barret (Military Attache )
Gauss (Ambassador)
J7z Kunming
(China) ammkun =
American military mission Kunming.
Bud Gura (formerly Italian East Africa) amgad
= ?
Signature: Bishop,Signals.
Flicke is
obviously describing ACAN. This is confirmed by the ‘Signal Corps-The Test’
which also mentions the same stations, for example: ‘After the Signal Corps' first large transmitter in India, at Karachi,
had begun operation in April 1942, satellite stations rapidly sprang up.’
and ‘The direct WAR to Cairo (WVNV)
circuit, after barely two months of service, was discontinued on Christmas Eve
1942 in favor of relay of the Cairo traffic by way of Asmara (WVNT).’
Unfortunately
he doesn’t expand on the kinds of traffic being passed on these links or the
codesystems used. However we know that OKW/Chi could decode several US
diplomatic codes during the war.
Luftwaffe
Chi Stelle effort:
The Luftwaffe
Signal Intelligence agency‘s LN Abt 350 Referat
B in Asnieres, Paris intercepted USAAF
and Naval AF traffic both Morse and radio-teletype. This section reached its
peak in terms of importance in 1942-3. Then in 1943 the part that dealt with
USAAF ferry traffic was split up and sent to Munich-Oberhaching.
The section
of Referat B which was moved to Munich-Oberhaching in 1943 was named Referat B5.
There was a large intercept station monitoring USAAF ferry traffic close by.
‘European Axis Signal Intelligence in World War II’ vol5 gives more details on the
operations of Ref B5:
‘The new Section evaluated all traffic and
had the following responsibilities: a) The monitoring of the United States
proper, which although it only touched the surface, still furnished an insight
into the principal networks of the Army and Naval Air Forces, into training
activity, air transport, defense zones, and the activation of new combat
aviation units. b) The monitoring of the Atlantic ferry service. The Middle and
Central Atlantic routes were monitored by the W/T platoon in Oberhaching and by
Luftwaffe Signals Intelligence Service outstations in Spain, which operated under
the cover name of ‘Purchasing Agencies’; the North Atlantic route was monitored
by the 16th Co., LNR 3 and reports furnished to the Section. c) The monitoring
of the American Air Transport Command by the platoon in Oberhaching. d) The
monitoring of the RAF Transport Command and of both American and RAF troop
carrier commands. The greater part of this interception was also done in
Oberhaching.’
US
radio-teletype was also intercepted by a LN Abt 350 unit in Berlin-Schoenfeld. The types of traffic intercepted were
FF5 and FF6, which refer to 5-unit T/P and Radiotype respectively. A German
report from November 1944 says that the Schoenfeld unit had 14 Rhombus
installations, an intercept hut with 12 intercept rooms and total strength of
52 men. Intercept equipment was provided by Wa Pruef 7.
In postwar
interrogations German personnel mentioned that USAAF T/P ferry traffic was read
during the war.
Friedrich,
head of Luftwaffe signals intelligence, stated in TICOM I-13:
‘KAMERUN’
(CHI Stelle Ob.d.L., Referat B) when located at PARIS-ASNIERES had intercepted
and broken U.S. non-morse teleprinter traffic between WASHINGTON and EUROPE.
This success was maintained throughout owing to the lamentable insecurity of
the operators. The Germans had therefore always known all details of ferry
flights, strength of the U.S. Air Force in Europe and a good deal about
training and replacements.’ and ‘Yes.
It was wireless teleprinter traffic from Washington State Department. No. Not
to Europe: to overseas W/T stations. It was a 'Zutraegerverkehr, (traffic
passing on signals in bulk). There was an immense volume of traffic. Breaking
ceased when a new machine or a new 'Tastschritt’ (keying tempo ?) was
introduced. Yes, there was a secrecy device, but it could be broken by the most
primitive methods; there were 10 GAF WAAF only to cope with it. The traffic did
not carry signals of any tactical importance. No, this was not before, but
after, the Americans entered the war. But breaking ceased a long time ago. Yes,
a special receiver had to be built. 'As far as I can remember, but I don't want
to be bound to the statement, the receiver was built for me by a Feldwebel'.
The alphabet was a kind of morse substitution. What should have been A came out
as, say, M. No, it was not this impulse business.’
The follow-up
report I-29 says:
1. Reference was made to Friedrich's
previous statements about the breaking of an American
"Funkfernschreib" system. See Ticom/I-13. ((Note: as will be seen,
the whole difficulty about this claim arose from his use of the quoted term
'teleprinter' when he meant in fact 'undulator', and from a misunderstanding
about the terminals of the traffic)). He was asked when the breaking began, and
stated that it was shortly after the entry of the U.S. into the war. It was
traffic between the War Dept and the regional traffic collecting centers, he
could not recall the locations of these centers, but they were all within the
United States. They were specifically not in Iceland or Greenland. The
transmission was described as teleprinter ((wrong)) short-wave. It was
encinhered but was easy to break. It was Morse traffic, not impulse. It was
recorded by teleprinter ((i.e. undulator)) on a printed strip as dots and
dashes [but see below]. This was enciphered morse, not clear text. He had a
special receiver built by a Feldwebel for taking it. it was multi-channel [but
see below]; he does not know what kind. The contents of the traffic were: training
instructions, development of airfields and details of selective service
processes.
2. He was asked whether this was the
traffic from which he had said they got details of ferry flights; it was,
particularly details of the preparations for flights and of the routes. The
traffic dealt with the bringing of aircraft to assembly points, then their
transfer to ferrying ports, and finally with their flights to North Africa,
Gibraltar, and later straight to Great Britain.
3. Was the morse just scrambled for
transmission, or was there a cipher underneath? Didn't know. After unscrambling
the channels, did you have clear text, or was there a further encipherment to
solve? Reply: there is a misunderstanding. The multichannel scrambling method
to which we referred is the method used by the Americans later on, and which
the GAF failed to break, because of lack of apparatus. The traffic in question
was originally just Plain morse. The new "Tastschritt" affected only
the German interception, not us. Asked to define Tastschritt, he said it did
not mean "keying speed", but the synchronizing of the intercept
equipment with the recorder. He was asked to explain the inconsistency of his
referring to the traffic both as teleprinter and as morse. He then drew a
picture of an undulator tape, single-channel, and marked off the undulation
into successive Morse letters. He said this was what he meant by
Funkfernschreib. Each letter was different from the corresponding clear text
letter. He could not remember any of the indicators. The preamble gave ample
routing instructions, and enabled them to couple the names of towns with
call-signs and personal names. The text itself was very stereotyped, especially
the addresses. He did not recall whether cleartext was mixed with cipher. He
was asked whether they considered it a high-grade system, and replied that they
did not, but that there was so much material in it, that if they could have
allotted it sufficient time and personnel, they would have got a good deal of
valuable information from it. It dealt in addition with the production and
development of aircraft. However they had other things to do, and other sources
of information, so this materiel was not fully exploited. We asked what these
other sources were. He said all of the ferry-flight air-ground traffic was read
by III/LN Rgt 3 also in Sicily and gave expected times of arrival and
departure, weather, and strength of groups of planes being ferried.
4. It was asked whether the morse
signs on the undulator were converted into letters or figures. They were
letters. When did the breaking cease? He found this very difficult to recall.
It was long before the invasion of France. We asked if it was before the
invasion of North Africa. He said it was at just about that time, but he could
not remember whether it was shortly before or shortly after. Asked what the
change was, he could not recall. Was it to teleprinter or to multichannel. He
thought it was not teleprinter as he had never had a receiver built which would
take that. Question: Then they were still able to intercept it? Yes. In what
form? Doesn't know. Still on tape? He thinks so. Who else intercepted this type
of traffic-what other units? OKW did. In Husum? No. Dr. Pickering then said
that FNAST 3 (Euskirchen) personnel had told a somewhat similar story (to be
published). He replied that it was very likely that this was the same traffic,
as KAMERON (unit intercepting for GAF) corresponded with Euskirchen on systems
which they both worked on. He agreed with the Euskirchen statement that it was
a simple substitution. ((Comment: Not too much credit should be placed in this
statement, as he was just adopting a suggestion)).
Voegele,
chief cryptanalyst of the Luftwaffe in the West said in I-112: ‘From April to October, 1944, clear radio T/P
messages were intercepted regarding a/c movements between America and North
Africa. similar messages in cypher with 6 letter indicators were also
intercepted but these could not be read.’
The Army Airways
Communication Service
During the
war special support was given to the AACS which belonged to the Airforce.
According to the ‘Signal Corps -The Outcome’: ‘AACS differed from ACAN in that it was strictly an AAF organization,
manned and operated by the airmen, though Signal Corps men supplied the
equipment, engineered and set up the installations, and in the early days of
the war often operated the communications lines too, until the AAF could do so
with AACS men, who very often merely transferred over from the Signal Corps.’
It seems
reasonable to assume that the networks exploited by the Luftwaffe belonged to
the AACS. That would explain the traffic dealing with aircraft movements.
Apart from
Morse, the AACS was provided with single-channel radio-teletype with automatic
enciphering in order to deal with the traffic loads it transmitted daily. The
official history ‘Signal Corps -The Outcome’ says: ‘It was the South Atlantic route to Africa and Europe that first got the
single-channel RTTY net, along the string of Caribbean islands to the bulge of
Brazil, across the South Atlantic via Ascension Island, reaching Dakar by
mid-1943.’
OKH/GdNA
effort:
The German
Army’s Signal Intelligence agency - OKH/GdNA had a special group that
intercepted high level enemy radio-teletype traffic. This was Group VI split into
Referat 1 operating in the East and Referat 2 in the West.
The Ref 1
unit intercepted Soviet multichannel radio-teletype, both plaintext and
enciphered, with special equipment. Members of this unit were captured in May
’45 by the Allies and taken to the UK with their equipment.
The Ref 2
unit was based in Euskirchen, Germany. This was the base of Feste 3 (Feste
Nachrichten Aufklärungsstelle/Stationary Intercept Company).
According to
report ‘CSDIC 1717’ Group VI Ref 2 was headed by inspector Heller and was divided
in Ref 2A which evaluated the British and American T/P and automatic Morse traffic
and Ref 2B that intercepted it. Roeder, head of Group VI at the end of the war,
stated in TICOM I-99 that the Western unit had about 15 soldiers and 30 helpers
plus 10 receiving apparatus.
US traffic
was also picked up by Feste 9 in Norway. In report CSDIC/CMF/Y 40 it is stated
that Feste 9 intercepted US traffic both manual and automatic from domestic
bases and stations abroad (Atlantic area, Caribbean, Middle East, India).
Some of this
traffic was enciphered with systems that the Germans had solved. These were the
War Department Telegraph Code, the Division Field Code and the M-94 strip
cipher.
There was a
special device ‘funkfernschreibverkehr’
used by funkmeister Rudolph ‘an expert on WT TP intercept’. This is a reference to the interception of Baudot
radio-teletype and Radiotype.
IBM Radiotype,
APO numbers and promotion letters
In order to
build a modern communications network the Signal Corps wanted radio-teletype
units with automatic enciphering and deciphering capability. In 1942 they did
not have such equipment so they had to settle for a similar machine called
radiotype.
‘The first working model of the Radiotype was
fabricated in 1931 in the laboratory of Radio Industries Corporation under the
direction of Walter S. Lemmon, who was then the company's president, Clyde J.
Fitch, an engineer, and A. M. Nicolson.
……………………………………………………………………………………………………..
In 1935 Admiral Richard E. Byrd
successfully sent a test Radiotype message 11,000 miles from Antarctica to an
IBM receiving station in Ridgewood, New Jersey. Six years later, IBM lent
Radiotype machines to the U.S. Signal Corps for tests between Washington, D.C.,
and Dayton, Ohio. These tests were conducted by Albert Holt, an IBM field
engineer in the Radiotype Division. With the U.S. entry into World War II, the
Signal Corps ordered quantities of the Radiotype machines to equip its stations
in San Francisco, Honolulu, Panama, Puerto Rico and elsewhere.’
The ‘Signal
Corps-The Test’ says: ‘The International
Business Machines Corporation had worked out an imperfect solution involving
equipment that the firm called radiotype, using, unfortunately, not the
standard five-unit teletypewriter code but a special six-unit code. Like a
narrow gauge railroad adjoining a standard line, this special code necessitated
much hand labor at conversion points where standard teletypewriter texts had to
be shifted onto radiotype circuits, and vice versa. Moreover, the standard
automatic cipher machines could not function with the six-unit system.
Notwithstanding these inconveniences, the Signal Corps early in the war began making
use of radiotype, leased from IBM. It was another step in the right direction, toward
automatic, high-speed, heavy-duty communications for the Army.’
According to
the same source the use of radiotype was extensive during the war: ‘Radiotype would continue to be used
considerably. Not till September 1943 would the Signal Corps stop its procurement
in favor of radioteletype and not until May 1945 would the Army take its last
radiotype out of service (on the WAR-Accra circuit). Then the triumph of
radioteletype would be complete.’
The Germans
were able to exploit the internal US traffic from 1941 onwards. The Army
intercepted it from Euskirchen and from Norway.
By monitoring
the internal US radio traffic the Germans could follow the activation and
movement of units through their APO (Army Post Office) number. It was
understood that divisions sent to West coast harbors went to the Pacific
theatre while those sent to East coast harbors went to the Atlantic theatre. Valuable intelligence was
also gained from officer’s promotion letters.
Initially
this traffic was Morse but the introduction of radiotype forced the Germans to
build specialized intercept equipment.
FMS P-038
says: ‘In the spring of 1942 a new
transmitting technique was introduced in American long-distance communication
(both domestic and foreign) that dried up this excellent source of German
intelligence. The Euskirchen station, which was charged with cryptanalysis of
this traffic, solved the riddle within one week, however, by means of tape
recordings and systematic analysis. It was finally discovered that the process
used was a rapid system of wireless telegraphy which differed from the usual
method by the number of current impulses. This was the ‘Radiotype’ method. A
tremendous number of military and business messages were soon intercepted.
After a short while the receiving operators were able to ‘read’ the message
tapes as fast as Morse code. Fortunately, after a pause of one week, military
messages in clear text became more frequent for a time. This mistake was not
discovered by the Americans until later, at which time they began to encipher
these mechanically transmitted messages. Since it was no longer possible to
solve them, work on these messages was discontinued.’
This may
refer to the introduction of the SIGCUM cipher machine in early ’43 and its
immediate withdrawal due to a security problem. Or it could refer to operator
mistakes described in ‘The Signal Corps-The Outcome’: ‘The on-line features had a serious security disadvantage, however, in
that the operator on the transmitting end sometimes forgot-when passing from
unclassified traffic sent in the clear to classified-to flip the switch that
would connect the on-line crypto equipment.’
The Germans
did not always get good intelligence from ACAN. David Kahn says that the Allies
managed to deceive them regarding the divisions sent to Britain in 1944 by
sending fake radio messages. However he doesn’t provide more details.
On the other
hand a member of Feste 3 named Wingender states in TICOM I-76 that even
‘fictitious stations and traffic’ were recognized thanks to violations of radio
discipline and cipher security.
Radio-teletype
and SIGCUM
Radiotype was
only a temporary solution and from 1943 it was being replaced by regular 5-unit
(Baudot) radio-teletype.
In order to
protect this traffic the Americans developed a cipher attachment that
automatically enciphered and deciphered the traffic. This device was called Converter M-228 or SIGCUM and
was introduced in January 1943.
Its initial
debut was not successful as a flaw in its security was found and a decision was
made to delay its entry into service for several months.
It was
finally put into use in April 1943. From then on ACAN teleprinter networks
would be secure from eavesdroppers.
Unanswered
questions
Although the
information we have is enough to form a rough understanding of German operations
there are many missing elements.
We lack
details on the history and performance of the German agencies regarding their
interception of ACAN.
What kind of
intercept equipment did they use? How much traffic did they intercept? How much
of it could they decode?
Did they
attack the SIGCUM traffic cryptanalytically or simply use it for traffic
analysis?
Another
important question is whether the Radiotype system was used with a cipher
attachment of some sort. Was that the simple substitution that the Germans talked
about? We do know that standard cipher attachments could not be used on it
because of its 6-unit operation.
‘Building IBM: Shaping an Industry and Its
Technology’ says in page 348: ‘The use of Radiotype coupled directly to encryption and decryption
equipment, is reported by J. C. McPherson. 8 August 1991: discussion with E. W.
Pugh.’
Let’s hope
that some of these questions will be answered in the future.
Sources: The Signals Corps trilogy (US Army
publications), FMS P-038 ‘German Radio Intelligence’, ‘War secrets in the
Ether’, CSDIC 1717, CSDIC/CMF/Y 40 , TICOM reports D-4, I-13, I-29, I-42, I-64,
I-65, I-76, I-78, I-99, I-104, I-109, I-111,
I-112, I-149, Cryptologia article: ‘The Sigcum story: cryptographic failure,
cryptologic success’ , IBM website, ‘Hitler’s Spies’, ‘European Axis Signal Intelligence in World War II’ vol4 and vol5
