The Combined Cipher machine - 1942-1962

Cipher machines were extensively used by both the Axis and the Allies during WWII.

The Germans had the Enigma, the Lorenz SZ 40/42 and the Siemens T-52.

The Japanese had the Type B Cipher Machine (Angooki Taipu B).

The Americans had the Converter M-134-C (SIGABA) and the Hagelin M-209.

The British had the Typex.

Another machine that became increasingly important for the Allies, in the period 1943-45, was the Combined Cipher Machine - CCM. Unfortunately, this machine has not received a lot of attention from historians because there is limited information available on its internal operation and use in the field.

Here I have attempted to present information on the CCM from various sources that are not easy to find (the timelines section has detailed sources): 

The American M-209 cipher machine

At the start of WWII, the US armed forces used various means for enciphering their confidential traffic. At the lowest level were hand ciphers. Above that were the M-94 and M-138 strip ciphers and at the top level a small number of highly advanced SIGABA cipher machines.

The Americans used the strip ciphers extensively however these were not only vulnerable to cryptanalysis but also difficult to use.  Obviously a more modern and efficient means of enciphering was needed.

At that time Swedish inventor Boris Hagelin was trying to sell his cipher machines to foreign governments. He had already sold versions of his C-36, C-38 and B-211 cipher machines to European countries. He had also visited the United States in 1937 and 1939 in order to promote his C-36 machine and the electric C-38 with a keyboard called BC-38 but he was not successful (1). The Hagelin C-36 had 5 pin-wheels and the lugs on the drum were fixed in place. Hagelin modified the device by adding another pin-wheel and making the lugs moveable. This new machine was called Hagelin C-38 and it was much more secure compared to its predecessor.

In 1940 he brought to the US two copies of the hand operated C-38 and the Americans ordered 50 machines for evaluation. Once the devices were delivered, they underwent testing by the cryptologists of the Army’s Signal Intelligence Service and after approval it was adopted by the US armed forces for their midlevel traffic. Overall, more than 140.000 M-209’s were built for the US forces by the L.C. Smith and Corona Typewriters Company. (2)

The American version of the Hagelin C-38 was called Converter M-209 by the Army and USAAF and CSP-1500 by the Navy. Compared to the original version it had a few modifications. The M-209 had 27 bars on the drum while the C-38 had 29. Another difference was that the letter slide was fixed. During operation the text was printed by setting the letter spindle on the left to the desired letter and then turning the hand crank on the right.

The M-209 was a medium-level crypto system used at Division level down to and including battalions (Division-Regiment-Battalion) (3) and even up to Corps for certain traffic. The USAAF used it for operational and administrative traffic and the Navy aboard ships. SIGABA was used for higher level messages (Army-Corps-Division) and hand systems like Slidex and the Division Field Code used for tactical messages (Battalion-Company-Platoon).

The Germans called it ‘AM 1’ (Amerikanische Maschine 1) and the Japanese ‘Z code‘.

Update

In Compromise of State Department communications in WWII I made the following correction. I had written that the M-325 SIGFOY cipher machine was introduced into service in the second half of 1944, however that was not correct.

According to NARA - RG 59 - Purport Lists for the Department of State Decimal File 1910-1944 – microfilm 611 - 119.25 MC-325 the device was distributed to foreign posts in the second half of 1944 but the keylists were for the period January-June 1945. Thus the device could not have been used in 1944 by the State Department.

Information on State Department codes and ciphers

NARA has uploaded the microfilms containing entries on WWII era State Department codes and ciphers.

The entries dealing with cryptology are the 119.25.

Microfilm 444

Microfilm 445

Microfilm 611

German solution of State Department A-1 Code in 1944

During WWII the US State Department used several codebooks for enciphering radio telegrams. These were the low level Gray and Brown codes and the high level A1, B1 and C1 codes.

The latter codebooks were used with substitution tables.

It is clear that the German codebreakers were able to solve the substitution tables used with the A1 and C1 codes till late 1943 because these were given to the Japanese and decoded by the Allies in late 1944 (1):

According to a message of the Japanese military attaché the C1 code continued to be used by the US embassy in Bern, Switzerland so those messages could be read in 1944 (2):

Were the Germans also able to read messages enciphered on the A1 codebook in 1944?

The book ‘Hitler, the Allies, and the Jews’ by Shlomo Aronson mentions a message solved by the codebreakers of OKW/Chi (German High Command’s deciphering department) (3):

‘At the same time, the OKW/Chi decrypts tell us in their way what the Allies were doing in various ways, including the hectic activities of WRB's operatives upon its inception. Thus, the following cable from Washington, dated February 9, 1944, from the State Department and signed by Secretary of State Cordell Hull but in fact sent by the WRB to the American Legation in Bern, dealt with funds made available to the International Red Cross (ICRC) in Geneva to help Jews in Rumania, Croatia, Hungary, Slovakia, and Theresienstadt by the Joint Distribution Committee (AJDC), as authorized by the Treasury Department’.

The original message can be found in the US National Archives (4) and the classification is SECRET.

The note on the first page says A-1 so I assume that it was sent using the A-1 codebook. 

Thus it seems that the Germans continued to read diplomatic traffic sent on the A-1 code even in 1944.

Sources:

(1). US National Archives - collection RG 457 - Entry 9032 - box 1.018 - NR3225 ‘JAT write up - selections from JMA traffic'

(2). UK National archives HW 40/132 ‘Decrypts relating to enemy exploitation of US State Department cyphers, with related correspondence’.

(3). ‘Hitler, the Allies, and the Jews’, p200.

(4). US National Archives - Microfilm Publication M1284, roll 38, indexed to file ‘840.48 Refugees/5195’. 

The Higgs memorandum - Compromise of State Department communications by the Finnish codebreakers in WWII

During WWII the US State Department used several cryptosystems in order to protect its radio communications from the Axis powers. For low level messages the unenciphered Gray and Brown codebooks were used.  For important messages four different codebooks (A1, B1, C1, D1) enciphered with substitution tables were available.

Their most modern and (in theory) secure system was the M-138-A strip cipher. Unfortunately for the Americans this system was compromised and diplomatic messages were read by the Germans, Finns, Japanese, Italians and Hungarians. The strip cipher carried the most important diplomatic traffic of the United States (at least until mid/late 1944) and by reading these messages the Axis powers gained insights into global US policy.

Germans, Finns and Japanese cooperated on the solution of the strip cipher. In 1941 the Japanese gave to the Germans alphabet strips and numerical keys that they had copied from a US consulate in 1939 and these were passed on by the Germans to their Finnish allies in 1942. Then in 1943 the Finns started sharing their results with Japan. 

Finnish solution of State Department cryptosystems

During WWII the Finnish signal intelligence service worked mostly on Soviet military and NKVD cryptosystems however they did have a small diplomatic section located in Mikkeli. This department had about 38 analysts, with the majority working on US codes.

Head of the department was Mary Grashorn. Other important people were Pentti Aalto (effective head of the US section) and the experts on the M-138 strip cipher Karl Erik Henriksson and Kalevi Loimaranta.

Their main wartime success was the solution of the State Department’s M-138-A cipher. The solution of this high level system gave them access to important diplomatic messages from US embassies in Europe and around the world. 

Apart from purely diplomatic traffic they were also able to read messages of other US agencies that used State department cryptosystems, such as the OSS -Office of Strategic Services Bern station, Military Attaché in Switzerland, Office of War Information representative in Switzerland, the Foreign Economic Administration, War Shipping Administration, Office of Lend-Lease Administration and the War Refugee Board.

Operation Stella Polaris

In September 1944 Finland signed an armistice with the Soviet Union. The people in charge of the Finnish signal intelligence service anticipated this move and fearing a Soviet takeover of the country had taken measures to relocate the radio service to Sweden. This operation was called Stella Polaris (Polar Star).

In late September roughly 700 people, comprising members of the intelligence services and their families were transported by ship to Sweden. The Finns had come to an agreement with the Swedish intelligence service that their people would be allowed to stay and in return the Swedes would get the Finnish crypto archives and their radio equipment. At the same time colonel Hallamaa, head of the signals intelligence service, gathered funds for the Stella Polaris group by selling the solved codes in the Finnish archives to the Americans, British and Japanese. 

The Stella Polaris operation was dependent on secrecy. However the open market for Soviet codes made the Swedish government uneasy. In the end most of the Finnish personnel chose to return to Finland, since the feared Soviet takeover did not materialize. 

The Higgs memorandum

In September 1944 colonel Hallamaa met with L. Randolph Higgs, an official of the US embassy in Sweden and told him about their successes with US diplomatic codes and ciphers.

This information was summarized in a report prepared by Higgs, dated 30 September 1944.

The report can be found in the US National Archives - collection RG 84 ‘Records of the Foreign Service Posts of the Department of State’ - ‘US Legation/Embassy Stockholm, Sweden’ - ‘Top Secret General Records File: 1944’.

(Google Drive link)

Higgs met with colonel Hallamaa on September 29 and the OSS officials Tikander and Cole were also present during their discussion.

Hallamaa stated that he was an administrator, not a cryptanalyst and about 10-12 of his men worked on US diplomatic codes.

His unit had solved the US codes Gray, Brown, M-138-A strip cipher and enciphered codebooks (probably the A1, B1, C1).

The high level M-138-A system had been solved mostly by taking advantage of operator mistakes such as sending strip cipher information on other systems that had already been broken or sending the same message in different strips one of which had been broken.

The strip cipher was considered a strong encryption system and had been adopted by the Finns for some of their traffic.

Important diplomatic messages from the US embassies in Switzerland, Sweden and Finland were read by the Finnish codebreakers.

Regarding Bern, Switzerland most of the messages dealt with intelligence matters:

‘Replying to my request for information regarding the contents of the messages from our Legation in Bern to the Department, Col. Hallamaa said the great bulk of them were intelligence messages dealing with conditions in Germany, France, Italy and the Balkans. He spoke in complimentary terms about ‘Harrison’s’ information service’.

Regarding Helsinki, Finland Hallamaa stated that thanks to the decoded diplomatic traffic they were always informed of current US policy initiatives:

‘Col. Hallamaa said that they always knew before McClintock arrived at the Foreign Office what he was coming to talk about’.

Hallamaa revealed a lot of confidential information to the Americans and volunteered to have some of his experts interviewed. 

The interview was conducted on friendly terms with Higgs stating; ‘Col. Hallamaa was most pleasant and seemed to be entirely frank and open regarding the matters discussed’.

Additional information: In November 1944 the US cryptanalysts Paavo Carlson of the Army’s Signal Security Agency and Paul E. Goldsberry of the State Department’s cipher unit interviewed Finnish officials regarding their work on US codes. Their report can be found here.

The IBM Codatype cipher machine

In the files of the NSA’s Friedman collection there is a report by William F. Friedman, dated September 1937, which deals with a cipher machine called Codatype (1). 

Apparently David Salmon, the State Department’s chief of the Division of Communications and Records wanted Friedman’s opinion on the security afforded by the Codatype machine.

Although the device appeared to be ‘highly reliable, speedy and efficient’ Friedman’s conclusion was that ‘the degree of cryptographic security afforded by the machine is relatively low, and certainly not sufficient for governmental confidential or secret messages’ and ‘It is doubtful whether anything can be done to eliminate the more or less fatal cryptographic weakness of this model and still retain a machine and cryptographic system which will be practical for the purpose for which intended’.

Thus the Codatype remained a prototype and was not acquired by the State Department.

The device was designed by the IBM engineer Austin Robert Noll, US patent 2,116,732 (2):

Notes:

(1). W.F. FRIEDMAN LETTER TO DEPT OF STATE: CRYPTOGRAPHIC SECURITY OF CODATYPE CYPHER MACHINE; S-028,605

(2). Coding and decoding machine - US 2116732A

The Carlson-Goldsberry report - Compromise of State Department communications by the Finnish codebreakers in WWII

During WWII the US State Department used several cryptosystems in order to protect its radio communications from the Axis powers. For low level messages the unenciphered Gray and Brown codebooks were used.  For important messages four different codebooks (A1, B1, C1, D1) enciphered with substitution tables were available.

Their most modern and (in theory) secure system was the M-138-A strip cipher. Unfortunately for the Americans this system was compromised and diplomatic messages were read by the Germans, Finns, Japanese, Italians and Hungarians. The strip cipher carried the most important diplomatic traffic of the United States (at least until mid/late 1944) and by reading these messages the Axis powers gained insights into global US policy.

Germans, Finns and Japanese cooperated on the solution of the strip cipher. In 1941 the Japanese gave to the Germans alphabet strips and numerical keys that they had copied from a US consulate in 1939 and these were passed on by the Germans to their Finnish allies in 1942. Then in 1943 the Finns started sharing their results with Japan. 

Finnish solution of State Department cryptosystems

During WWII the Finnish signal intelligence service worked mostly on Soviet military and NKVD cryptosystems however they did have a small diplomatic section located in Mikkeli. This department had about 38 analysts, with the majority working on US codes.

Head of the department was Mary Grashorn. Other important people were Pentti Aalto (effective head of the US section) and the experts on the M-138 strip cipher Karl Erik Henriksson and Kalevi Loimaranta.

Their main wartime success was the solution of the State Department’s M-138-A cipher. The solution of this high level system gave them access to important diplomatic messages from US embassies in Europe and around the world. 

Apart from purely diplomatic traffic they were also able to read messages of other US agencies that used State department cryptosystems, such as the OSS -Office of Strategic Services Bern station, Military Attaché in Switzerland, Office of War Information representative in Switzerland, the Foreign Economic Administration, War Shipping Administration, Office of Lend-Lease Administration and the War Refugee Board.

Operation Stella Polaris

In September 1944 Finland signed an armistice with the Soviet Union. The people in charge of the Finnish signal intelligence service anticipated this move and fearing a Soviet takeover of the country had taken measures to relocate the radio service to Sweden. This operation was called Stella Polaris (Polar Star).

In late September roughly 700 people, comprising members of the intelligence services and their families were transported by ship to Sweden. The Finns had come to an agreement with the Swedish intelligence service that their people would be allowed to stay and in return the Swedes would get the Finnish crypto archives and their radio equipment. At the same time colonel Hallamaa, head of the signals intelligence service, gathered funds for the Stella Polaris group by selling the solved codes in the Finnish archives to the Americans, British and Japanese. 

The Stella Polaris operation was dependent on secrecy. However the open market for Soviet codes made the Swedish government uneasy. In the end most of the Finnish personnel chose to return to Finland, since the feared Soviet takeover did not materialize. 

The American reaction and the Carlson-Goldsberry report

According to the NSA study History of Venona (Ft. George G. Meade: Center for Cryptologic History, 1995), it was at that time that the Finns revealed to the US authorities that they had solved their diplomatic codes. On 29 September 1944 colonel Hallamaa met with L. Randolph Higgs of the US embassy in Stockholm and told him about their success.

In response two cryptanalysts were sent from the US to evaluate the compromise of US codes in more detail. They were Paavo Carlson of the Army’s Signal Security Agency and Paul E. Goldsberry of the State Department’s cipher unit. Their report dated 23 November 1944 had details on the solution of US systems.

The Carlson-Goldsberry report

Unfortunately locating this report proved to be quite a problem. Initially I searched for it in the US National Archives (both in the NSA and OSS collections) but without success.

Thankfully the NSA FOIA/MDR office has managed to locate this file and they have finally declassified it.

Google drive link

The 4-page report summarizes the information gathered by US officials from their interviews of Finnish codebreakers in 16, 18 and 21 November 1944.

From the Finnish side Erkki Pale (head of the department working on Soviet ciphers) and Kalevi Loimaranta (member of the department dealing with foreign diplomatic codes) gave a summary of their work on various cryptosystems.

The Finns admitted to solving US diplomatic systems, both codebooks and the strip cipher M-138-A. According to them an unenciphered codebook could be reconstructed in 6 months but an enciphered one was harder to solve.

Regarding the M-138-A cipher it was solved because the alphabet strips were used for long periods of time, the same strips were used by several users and the numerical keys were the same for all users. Stereotypical beginnings and endings were also exploited in assumed plaintext cryptanalytic attacks.

There was cooperation with the German codebreakers on US systems and the Finns received a lot of intercepts from them.

The Finnish codebreakers also used a number of IBM machines for statistical work.

Although the Finns stated that after the introduction of channel elimination in January 1944 they could no longer solve strip cipher traffic a memo included in the report says that their detailed knowledge of channel elimination procedures may indicate continued success with the M-138-A system.

Acknowledgments: I have to thank my friends in the US for requesting this file from the NSA FOIA/MDR office and getting it declassified.

Bye bye mr Hayashi

In 2017 I tried to locate a file in the US national archives called ‘Interrogation of mr Hayashi’. 

According to the NSA FOIA office it had been recently transferred to NARA as part of transfer group TR-457-2016-0009. The reference I was given by NARA pointed to 36 boxes that have not been indexed, so the file could not be located by my researcher. 

I tried to find the Hayashi file again this year by asking NARA’s research department if they could locate it but I was told that ‘We have carefully searched our holdings with a particular focus on Record Group 457 - Entry P4…….however, we were not able to locate the file’.

Thus it seems that this is the end of my quest for the Hayashi file.

Joint Chiefs of Staff evaluation of Office of War Information ciphers

During WWII the US Office of War Information engaged in intelligence gathering and propaganda activities against the Axis powers.

The representatives of the OWI used various cipher systems in order to protect their communications and these systems were examined by the Joint Chiefs of Staff.

A summary report was issued in July 1944 and it found problems with physical security, classification procedures, stereotyped messages and cipher reuse.

Regarding OWI ciphers it was noted that ‘Present double transposition keys have been in use since they were produced by the Signal Corps in late 1942 and early 1943’ and the recommendation was ‘That immediate supersession of these keys be accomplished and that provision be made for their more frequent supersession in the future’.

Source: US National Archives, collection RG 208, Office of Wartime Information: General Records of the Security Officer, Entry 9. Location:  350/71/17/6, Box 1. Folder Communications Survey OWI.

Acknowledgements: I have to thank Robert Hanyok for locating and copying the JCS evaluation.

Staff Study on OSS Cryptographic Plan - January 1945

Recently I posted reports on OSS codes and ciphers from 1943 and 1944.

Another document that has information on the OSS crypto systems is ‘Staff Study on OSS Cryptographic Plan’, available from the US National Archives - collection RG457- Entry 9032 - NR 3280 ‘Staff Study on OSS Cryptographic Plan’.

The report is also available from the journal ‘Cryptologia’, vol13, no.3:

 SECRET

HEADQUARTERS, ARMY SERVICE FORCES

OFFICE OF THE CHIEF SIGNAL OFFICER

WASHINGTON 25, D.C.

  SPSIC-6                                                                                            8 January 1945

MEMORANDUM for Assistant. Chief of Staff, G-2

Subject: Staff Study on OSS Cryptographic Plan

The enclosed staff study is forwarded for your consideration and comment,

For the Chief Signal Officer:  

                                                                                      W, Preston Corderman

                                                                                                                                                                                                                                          Colonel, Signal Corps

                                                                                                                                                                                                                                     Chiefs Signal Security Branch

1. Incl

Study on OSS Cryptographic Plan

STAFF STUDY ON OSS CRYPTOGRAPHIC PLAN 

PROBLEM PRESENTED

1. How may the need of OSS for a high grade, high speed cryptographic system be satisfied?

FACTS BEARING ON THE CASE

2. OSS has a requirement for a high grade, high speed cryptographic system for the encipherment and decipherment of secret traffic.

3. At the present time OSS is using the Converter M-134-A (short title SIGMYC) to satisfy this requirement.

4. Prior to 5 April 1944, eight (8) SIGMYC were issued to OSS.

5. The Assistant Chief of Staff, G-2, authorized the issue of twenty-six (26) SIGMYC to OSS by memorandum for Col. Corderman from Col. Clarke dated 5 April 1944, to meet the expanding needs of that organization.

6. Since 5 April 1944, twenty-one (21) SIGMYC have been delivered to OSS. That organization now holds twenty-nine (29) machines; five more are available for issue.

7. In the past OSS has used one universal set of rotors with SIGMYC. These rotors were replaced once.

8. In September 1944 OSS requested two new sets of rotors, one set to be used in Europe and the other set in the Far East. Thirty-eight (38) sets of rotors SIGRHAT (for use in the Far East) have been issued in compliance with that request.

9. Twenty-five (25) sets of rotors SIGSAAD (for use in Europe) have also been issued.

10. Instructional documents associated with SIGMYC are "Operating Instructions for Converter M-134 and M-134-A (Short title SIGKOC and ‘photographs and Drawings of Converter M-134-A (short title SIGVYJ). No copies of these publications are available for issue. This situation was caused by the destruction of the instructional documents when Converters M-134-A were turned in by Army holders.

11. Requests are received for spare parts with each request for the issue of a SIGMYC. The spare parts list always include rotor stepping solenoids. There are no rotor stepping solenoids on hand in this agency. Three requests for these items have not been fulfilled.

12. In accordance with authorization of the Assistant Chief of Staff, G-2, 27 July 1944, one SIGTOT room circuit was furnished OSS in Washington. Authorization did not extend to the issuance of tapes for use with this equipment. Additional SIGTOT circuits have been made available to OSS in Europe. That organization is procuring additional tape punching equipment to meet the increased demand for tape. OSS requested the loan of such equipment until they are prepared to fulfill their own needs for tape. This branch is supplying OSS with sufficient tape until that organization is self-supporting in this respect.

13. Four (4) SIGCUM have been issued to OSS with the approval of the Assistant Chief of Staff, G-2, 28 April 1944. These machines were sent to OSS in North Africa to replace four (4) SlGCUM which were loaned to OSS by NATO and subsequently recalled by the latter organization.

14. Within the past six (6) months the communications requirements of OSS have markedly increased. The cryptographic requirements have expanded proportionately. The rapid expansion is vividly illustrated by the strip cipher requirements of that organization. In June 1944 SSA requested OSS to furnish a monthly quota of desired material in order to adjust production schedules here. The monthly quota of strip cipher systems needed is now larger than the total number of strip systems issued to OSS over a period of twenty (20) months.

15. It is believed that the OSS will request the five (5) remaining SIGMYC of the authorized allotment of twenty-six (26) machines. Instructional documents are not available for issue with these converters. The reprinting of these documents presents a major reproduction job.

16. OSS encounters an ever present maintenance problem since the machines are constantly breaking down. It is believed that the time is not far distant when it will be impossible to maintain the machines adequately,

17. In order to provide new rotors in the future it will be necessary to have rotors returned from the field by OSS for rewiring. Thus, a rotation process will be established to meet new demands for rotors which will result in the wearing out of the rotors within a relatively short time. It is noted that it would take between one to two years to procure new rotors.

18. OSS is now trying out a modification of the standard --text deleted -- device, which utilizes -*- --text deleted--. That organization is contemplating an increase in the distribution of these --text deleted – to include the standard --text deleted – held by OSS, thus, permitting inter-communication between the two machines. The cryptographic principle involved his been approved by the Signal Security Agency. OSS plans to utilize the -*- --text deleted-- for secret radio transmissions.

19.  The question arises as to what other means are available. The following items of equipment are considered:

a. SIGTOT 

This system provides adequate security but the scarcity of equipment and the difficultly of providing sufficient quantities of one-time tape render its use impracticable. In addition SIGTOT is not at present adapted to multi-holders of a common system, which is an operational requirement

b. SIGABA

 Under present policy, it would be necessary to assign a crypt team with each machine in order to make them available to OSS. This presents a problem of securing sufficient personnel which appears insurmountable at the present time. Furthermore, the use of SIGABA as a solution to this problem is not generally regarded with favor.

c. SIGCUM

The communications and cryptographic problems of OSS are developing rapidly in the Far East where traffic is transmitted largely by radio. Since SIGCUM may not be employed for secret traffic transmitted by means of radio the use of this machine would not provide a solution to the problem, Although SIGCUM would be a satisfactory substitute for SIGMYC in Europe, a revision of the cryptographic facilities of OSS in that area is not considered feasible at this time.

d. SIGFOY

This converter provides adequate security to fulfill the need for a high grade cryptographic system and is well adapted to multiple holders of a common system. Since it is not a high speed system, it would not fulfill this requirement.

e. SIGLASE

This system would provide adequate security and speed to meet the outlined requirements. However, since SIGLASE is still in the development stage and the expected date of issue is unknown it is not the immediate answer to the OSS problem.

20. From the point of view of this branch the problem could be most acceptably solved by making Army facilities available to OSS. It is realized that the latter organization would probably not be favorably disposed toward such a solution,

CONCLUSIONS

21. The continued use of SIGMYC by OSS in the Far East will present maintenance and 

distribution problems which will be virtually impossible to solve.

22. A replacement for SIGMYC is needed.

23. SIGABA, SIGCUM and SIGTOT are not completely acceptable substitutes.

24. SIGFOY and SIGLASE would be a solution to the problem but since it will require from six to nine months to manufacture the SIGLASE, it cannot be considered an immediate solution.

25. It appears that the only immediate solution to the problem is for OSS traffic to be handled by Army cryptographic facilities.

RECOMMENDATIONS

26. That OSS be requested to utilize Army cryptographic communications facilities where such exist.

27. That OSS use its own cryptographic communications facilities where Army facilities do not exist.

28. That, at such time as the equipment referred to in paragraph 27 becomes unserviceable, service be maintained by those Army cryptographic facilities and/or equipments as may then be available.

A report dated 8 February 1946 (found in SRH-366 ‘The history of Army strip cipher devices’) has more information on the implementation of the aforementioned OSS cryptographic plan.