I• 

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REF ID:A60534 

SECRE'l· 

A. Important Contributions to Communications Security, 1939-1945. 

1. Converter M-134 A--On 25 July 1933 a secret patent application 

(Serial lfo. 682,096) was filed by the Chier Signal Officer, on my behalf, 

covering Converter M-134-T2, the predecessor of Converter M-134 C 

(Sigaba). The principle disclosed in Serial No 682,096 is of highest 

importance in that it was the first invention and disclosure covering 

Electrical control (as distinguished from mechanical control) of a set 

of cipher rotors in cascade, permitting a departure from the regular 

and periodic or metric angular displacements of such cipher rotors. 

The following is quoted from a Secret Navy report* on the history of 

the development of the Sigaba (ECM): 

11However, under date of 25 July 1933, The Chief 

Signal Officer filed on behalf of Friedman a patent 

application (Serial No. 6821 096) covering a cryptographic system and machine in which the stepping of 

the code wheels was very irregular and under the 

control of a keying tape. Electric Control thus made 

its first appearancel 11 "' 

A complete assignment of all rights to my invention was made to the 

Secretary of 'War on 10 September 1936, and the patent application was 

placed in the secret category on 9 September 1936, where it still remains. 

Two service test models of Converter M-134-T2 were constructed by 

the Signal Corps Laboratories at Fort Monmouth, New Jersey in 1936 and 

service tests were conducted by an exchange of cryptograms between the 

War Department, Washington, and The Panama Canal Department, Balboa, c.z., 

in November 1936. It demonstrated that the machine was operable at the 

rate of 30-35 words per minute and afforded the highest degree of security 

yet attained by any cryptographic machine for cryptonet communication 

(multiple holders of the same cryptographic key). 

On 19 February 1937 the military characteristics of Converter M-134 

wei•e approved, soon thereafter a contract for the construction of 12 

machines was placed with Wallace and Tiernan, Indiana, of Belleville, 

New Jersey. The machines were delivered to ~!Tashington on 2 August 1938. 

I developed and wrote the cryptographic keying instructions and in 

October 1938 first shipment was made of the machines, two each, for the 

Headquarters of the Ninth Corps Area (San Francisco), Panama Canal, 

Hawaiian, and Philippine Departments. Four machines were kept in 

Washington. The .machines were promptly put into service for all the 

highly secret communications betlveen the War Department and the headquarters indicated. Later, as more machines became available, a further 

distribution was made to equip all Corps Areas and Departments, including the Puerto Rican, with a sufficient number of machines to meet 

Declassified and approved for release by NSA on 07-18-2013 pursuantto E .0. 1352a 

i~ See Enclosure labelled "Exhibit 411 

~ECREl. 

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REF ID:A60534 

8£CRET • 

requirements. Eight machines were placed in the \far Department Code 

Center. Only 75 of these machines were built in all but they formed 

the backbone of the quipment for high conll~~nd secret and confidential communications of the War Department and the Army from the date 

of their introduction into service until the end of 1941, when they 

were replaced by Converter M-134-C, the Sigaba. In 1940 the War 

Department sent by special officer courier two of these machines to 

the U. s. Military Attache in London, to meet the very urgent needs 

r'or high speed, high-security conununication between Washington and 

London. Later two more were sent there, making four for the Military 

Attache. 

On 29 H'ovember 1941 the War Department provided the Department 

of State with four machines, two for Washington and two for the 

American J!mbassy in London; later on, four or more additional machines 

were provided the Department of State. During the vital years 1940-

1942, confidential and secret intercommunication between these two 

points and among the of fices indicated could not have been successfully 

conducted without these machines. 

In January 1942 arrangements were made to use the M-134-A for 

direct communication between the President and the British Prime 

Minister and it uas used for this purpose for a number of months. 

Later this machine in that circuit w ... s replaced by Converter M-134 c, 

in a special adapter made under my supervision by the Signal Corps 

and the Western Union. This permitted of hi~h speed, secure conununication between the White House and Downing Street at a vecy critical 

period. 

The M-134 was also used to a large degree by the Signal Intelligence 

Service itself for forwarding intercept traffic to Washington from overseas intercept stations. It replaced Cipher Device M-138 for this purpose 

and thus greatly facilitated the prompt receipt of the raw traffic for 

cryptanalysis. 

later on, a number of them (totaling 29 or 30 at the end) as they' 

became available, were provided the Office of the Coordinator of Information (later the Office of Strategic Services) for secret communication 

between Washington, London and other capitals where the OSS maintained 

headquarters. Some of these machines (about 16) maybe and probably are 

still in service. 

During the years from 1939 to 1942, when Converterm. M-134 was 

replaced by Converter M-134-C (Sigaba) it is doubtful if the voluminous 

secret and confidential traffic of the highest echelons of the Army and 

the War Department could have been handled as successfully as it was, 

had it not been for the invention, development and availability of this 

machine. 

There is not a scrap or evidence in Ticom reports tl1at either the 

Germans or t.he Japanese or any other government was able to solve any of 

the traffic enciphered by ~sC:ftE:\Q.e. 

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2. Converter M-134-C (Sigaba).--In the course of studies of 

Converter M-134-T2 and before manufacture of the latter machine was 

well under way, my principal assistant, Mr. Frank B. Rowlett, and I 

investigated various means of improving the cryptographic machine with 

a view to eliminating the perforated tape which controlled the aperiodic 

stepping of the rotors. Various schemes were studied, including cain 

wheels with different diameters and variable 11 off'" and "on" pin arrangements. About 15 June 1935 Rowlett conceived an idea which finally 

resulted in making it possible to eliminate the tape control. Basically 

his invention was that of using a set of rotors as a key generator, that 

is, using the rotors to generate a long keying sequence by sending 

electrical impulses through a set of rotors which themselves were caused 

to step in a regular manner. The successive elements of the keying 

sequence, as they were generated could control the stepping of the 

rotors actually employed to encipher the letters of the message to be 

enciphered. Rowlett and I then jointly developed the idea by setting 

down on paper various met.hods by which it could be applied to replace 

the tape control employed in Converter M-134-T2, and although no models 

were built the results of our theoretical studies were incorporated in 

a patent application filed on 23 March 1936 (Serial No. 70,412) in our 

name as joint inventors. A complete assigrunent of the invention to the 

Secretary of War was made on 2 April 1936 and the pa.tent application was 

placed in the secret category, where it still remains. 

The Navy was then trying to improve its own machine (Mark IE CM), 

the security of which was unsatisfactory. Though this machine generated 

a long keying sequence the. number of available starting points in that 

sequence was so limited that considerable 11 depth11 , that is, messages 

enciphered in exactly the same key, could be expected every day and 

thus solution potentially made relatively easy. On three occasions, at 

Navy request, the drawings and principles later embodied in Serial 

No. 70,liJ.2 were shown and explained to Navy representatives several 

times in October and November of 1935, with the result that the Navy 

initiated a development contract with the Teletype Corporation and 

work thereon was started in January 1938. This was done,, however, 

without advising us or anybody else in the Signal Corps until March 

1939, when the Teletype Corporation engineers brought to Washington 

the first completed set of drawings of the Mark II E C M. Rowlett and 

I were invited to the conference with the Teletype engineers and in the 

course of the discussions it was brought out and acknowledged that the 

Navy had based the cryptographic features of the new machine upon the 

Army's disclosure. A first model was then built and delivered on 

3 February 19401 when Major General Mauborgne, then Chief Signal Officer, 

Rowlett, and I were invited by Admiral Noyes and Captain Safford to see 

the model. On that occasion Captain Safford acknowledged, in the presence 

of all those witnessing the demonstration, the fact that the Navy had 

used the Friedman-Rowlett invention. Further development of the machine 

was thereafter on a joint .Army-Navy basis, and on 19 June 1940 the 

Signal Corps added its order of an initial 85 machines to the Navy 

order, at a cost of ~1856.90 each. 

•r·--RET ,._.! ........ st 

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REF ID:A60534 

The Mark II ECM (Navy nomenclature)~Convert~r M-134-C was 

adopted by the ArmY to replace Converter M-1~4 A, not because the 

former might afi'ord greater security than the latter but because the 

M--134 C WciS not only a much more rugged, reliable and rapid ma.chine 

but also because it dispensed with perforated tapes, thus being more 

practical than the M-1:,4 C. The following is quoted from the Navy 

Department's "History of the ECM: 11 

"Electric control of the ECM by means of the FriedmanRowlett 'Stepping Maze' is the essential feature that places 

the Mark II ECM in a class by itself as regards security. 11 

On 17 March 1941 the first 10 machines were delivered to the Signal 

Corps and were given a prompt service test, which proved the machines to 

be hip,hly satisfactory. On 4 October 1940 action was initiated by the 

Signal Corps to procure an additional 149 machines, and thereafter, in 

successive contracts sevei·al thousand more of them were procured, the 

production schedule in July 1942 calling for the delivery of the machines 

to the Signal Corps at the rate of 150 per month. By 31 August 1942 a 

total of 373 Sigabas had been delivered and 364 were already in service; 

by 30 April 1943 the total number ordered was 1867, the number delivered 

w~s 862, and the number in use 807; by 28 March 1944 a total of 333 

machines had been ordered, 1827 delivered, and 1681 were in service. 

In all, the Signal Corps actually procured a total of 3392 of these 

machines for Army use, and the Navy procured more than that number 

for 1-lavy use. In the Army the machines v;ere distributed to all 

corrur.ands down to and including headquarters of Divisions. They were 

also used in all the important fixed headquarters in the Communications 

Zone, in all theaters and in the U. S. Under special precautions they 

were used in U. s. installations in foreien countries where we had no 

troops, as for example, in Moscow, for our special military mission. 

Whenever and wherever the late President went during the war, the 

Sigaba went too. They were installed in the late President's signal 

center whenever he visited his home at Hyde Park; they were on board 

the Presidential Train, etc. 

The fact that identical machines were employed by the Army and the 

Navy at all high and intermediate headquarte!'s not only speeded up the 

exchange of classified messages of all categories (secret, confidential, 

and restricted) within each of the Services but also facilitated Joint 

Communications. The following is also quoted from the Navy's History 

of the ECM: 

"This use of an identical machine with interchangeable 

code wheels has been of great military value, particularly 

in the early stages of the •var, when distribution of machines 

and code wheels was incomplete. In the Philippines, Java, 

Australia, and even in North Africa, Navy wheels have been 

used in .Army ECM1s, Army Wheels in Navy F.C:M's; machines have 

been borrowed back and forth between the two services; Army 

messages have been sent in Navy ECM ciphers and Navy messages 

sent in Army ECM ciph~:rs,•.• . ~ ,£al;;aKi!. l 

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REF ID:A60534 

:..,t:tltC lW'e know now from Ticom reports that neither the Japanese nor the 

Germans had the slightest success in their efforts to solve messages 

in the Sigaba, though t.he Germans certainly tried hard enough. The 

absolute security of Army and Navy high conun.and and high echelon 

com.'ll'Ullications throughout the war was made possible by the Sigaba. 

In view of the fact that the high-level communications of the German, 

Italian, and Japanese Goverrments and Armed Forces were successfully 

attacked by the U. S. and the British communications intelligence 

staffs, and that the intelligence resulting therefrom was of highest 

diplomatic, strategic, and tactical importance, whereas our own highlevel communications were inviolate, it may be said that the Sigaba 

contributed materially to the successful outcome of the war. 

3. Converter ~28 (Sigcum, Sighuad).--The need for a cryp.-

tographic mechanism to protect land-lines teletype communications was 

felt even in World War I. In 1936 the Army was anxious to have something practical developed for this purpose and studies that had been 

underway for a number of years culminated in 1939, when Rowlett and I, 

applying Rowlett 1s idea of using cascade rotors as a key generator, 

then jointly conceived the principles underlying what later became 

Converter M-228 (Sigcum). Patent Application Serial No. 443,320 was 

filed on 16 May 1942; assignment of rights to the Secretary of War 

' 

~·1as signed on 13 May 1942 and the application was placed in the Secret 

category, where it still remains. 

On 16 July 1941 military characteristics were approved by The 

Adjutant General and the Signal Corps Laboratories at Fort Monmouth, 

New Jersey, undertook the developraent. On 12 March 1942 a satisfactory 

service test and working demonstration of the first two models of Convert~r M-228 was made; one machine was at Fort Monmouth 1 the other 

at the Bell Laboratories, Uew York City. The provided for automatic 

on-line ke;Vboard encipher~ent, transmission, reception, decipherment 

and printi~ of messages at the rate of over 360 characters (= approximate- ly 60 words) per minute 1 with good security. 

On 7 April 1942 the budget for FY 1943 included provision for 

procurement of 2400 machines at $500 each 1 a total of $1,200,000. 

On 18 June 19l~2 representatives of the Signal Corps and the 

Navy witnessed a demonstration of the machine in New York and as a 

result the Navy decided to procure 200 for its use. 

On 24 November 1942 action was initiated to purchase 1467 machines 

and on 25 December the first 10 machines were shipped from the factory 

to Washington. 

~LUHET 

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--SB€lttT 

Although Converter M-228 was not intended for radio-teletype 

usage, the urgent need for speed in overseas communications and the 

availability of radio-telei:.ype circuits practically forced the use 

of the machine on these circuits to protect these communications. 

On 9 January 194) the first official message using Converter M-228 

on a radio circuit was sent from Washington to Algiers, and thereafter 

extensive use of the machines for radio-teletype communications was made, 

although it was decided, for security reasons, to transmit only confidental and restricted messages by this means. (Secret and Top Secret 

Messagt::s had to be enciphered by Sigaba or by Sigtot, the one-time tape 

System). 

By 11 September 1943 a total of 386? machines had been ordered, 

and 3044 had been manufactured. The rate of production was 500 per 

month. By tbat date the "stop-gap" teletype-encipherment system 

using twt) short loops of key tape was discontinued, because general 

distribution of the M-228 had been completed. On 31 May 1943 the 

A. C. of s., G-2, War Department, approved the installation of this 

machine for use on the Defense Teletypewriter Network linking the 

several U. S. Army Headquarters in the United Kingdom. 

In April 1944 the War Departr.lent approved a policy under which 

the machine could be turned over to the British for the specific 

purpose of use in Combined Operations; and on 23 May 1944 the A. C. 

of s., G-2, War Department, approved disclosure of the principles 

of the machine to the British. 

By 5 June 1944 a total of 3200 of these machines had been built 

and 1488 issued fo~ use, including 200 to the Navy. The machine was 

employed to encipher a tremendous volume of traffic, including raw 

material for cryptanalysis from all intercept stations. Under the 

special conditions and with some modification (Sighuad) the machine 

was also used in special circuits in Washington, between Arlington 

Hall Stution, the iti.litary Intelligence Service in The Pentagon, of 

the highest classification. This same modification (Sighuad) 

permitted the machine to be used by the Air Forces in the U. S. and 

in the Pacific, to transmit, by radio meteorological and weather data, 

thus greatly facilitating operations. 

The British did not have any machine similar to the Sigcum or 

Sighuad and only at the end of the war was their long-standing desire 

to be able to use it granted. The Germans had teletype encipherment 

equiμnent but a large volume of traffic in the various types of 

machines they built was solved and read on a current basis by the 

British. Toward the end of the war the Ger.in.ans had improved models 

which resisted solution, but they came too late. The Japanese had 

no such equipment at all. 

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-SECkETResults of Ticom operations have established that neither the 

Germans nor the Japanese were successful in their efforts to solve 

our Sigcum traffic, despite its great volume, and it is my belief 

that had we used this machira for secret radio-teletype communications no serious harm to our security woulu have followed. 

Although it was not used for secret radio-teletype communications, 

the machine was nevertheless widely used for secret, confidential, 

and restricted communications by land-line teletype and for a great 

volume or confidential and restricted comnlunications by radioteletype in the U. s. as well as in all overseas theaters. The 

Sighuad version of this machine \'fc1.s, ho\'Vever, used to a limited 

extent for secret traffic by radio. Had we not possessed such a 

machine our rapid communications v;ould have been severly handicapped by the necessity of encipherment by slower l!leans. 

4. Cipher Device ~M-138.-Early experiments with the old 

cylindrical Cipher Device M-94, which had been introduced into the 

u. s. Army and U. s .. Navy Lri about 1922, began in about 1933· 

Various modifications, in ~he form of a flat cipher device using 

variable, instead of fixed alphabets, were made, culminating in a 

device on ~i1ich a patent application in my name was filed (Serial 

No. 300,212) on 19 October 1939. On 16 July 1940 the application, 

which the usual license rights were assigned to the Government on 

16 Oc~ober 1939, was placed in the secret category under the provisions 

of the Act of 6 October 1917 as amended 2 July 1940. 

About five thousands of these devices were manifactured under 

War Department Contracts. They were used throughout the war and are 

still used by a large number of military fixed and mobile headquarters. 

In fact, until the manufacture of the automatic cipher machine (Sigaba) 

had progressed to the point where a suffieient number had been produced 

to meet distribution requirements, the Strip Cipher System using Cipher 

Device M-13$ formed the backbone of Army Secret and Confidential communications; thereafter it served and still serves as the secondary 

or back-up system for the holders of the Sigaba. For stations not 

equipped with the Segaba the Strip Cipher System still constitutes 

the principal means for such conununications. At the present in the 

u. s. all Posts, Camps and Stations use this device as the primary 

cryptographic means. Until recently it was also the primary means 

for communication between the War Department and all Military Attaches 

as well as for intercommunication among military attaches; at present it 

is employed only for circular messages to or among military attaches. 

The same device was also provided by the War Department in large 

quantitites for use by the Department of State, for Secret and Confidential Communications between that Department and its Einbassies, 

Legations, and Consulates, as well as for intercommunication among 

those offices. 

SECRET 

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SECRE'f 

Certain Allied Services, such as the British, Italian, and 

rl.ussian were also provided with these devices in small quantities 

both by the har and the Navy uepartments. The U.S. Navy also adopted the device at first in practically identical form; the Navy produced some minor improve~ents later on and employed and is still 

employing the device very extensiv~ly in its own communications. 

In addition the Strip Cipher System was used during the war as a 

Joint Army-Navy system and as a Combined System. The fact that the 

same device was used by both the Army and the Navy greatly facilitated 

Joint Com~unications. The production of the paper strips bearing the 

variable cipher alphabets employed in the device presented numerous 

problems which were successfully solved by me or by people under my 

direction. I conceived the first rotary cutter for cutting the strips 

apart and had the first cutter built at the Government Printing Office. 

This machine greatly facilitated the production of the strips and made the 

matter practical. 

5. General.-Throughout the years mentioned, in my capacity as 

Head Cryptanalyst and later as the Director of Com.,unications Research, 

znany proble~s directly related to our corrun.unications security were 

brought to my attention and I believe that my long experience in the 

field formed a solid foundation for mature, sound judgment in arriving 

at proper, practical, and satisfactory answers to those problems. 

Before our Converter .M-228 was ready for distribution the urgent 

need for a means of encipherin,g teletype communications for the Military 

Intelligence network in the United States led to my suggesting the 

adoption of a t.emporary expedient for this purpose. This took the 

form of double-loop, key-tape encipherment system 1·1hich had been tried 

out in a small way at the end of World War I. Having studied this 

method in 1919-1921 and kJ.101tlng the pitfalls to which such a system is 

subject from the security point of view, I was able to suggest ~ays of 

usage to minimize the dangers inherent in a double-tape encipherment 

method. The system was used for a number of months not only within 

the U. S. but also within theaters of operations, thus meeting an 

urgent need for teletype encipherment until the M-228 was ready for 

distribution. 

rater on, when the one-~ime tape or Sigtot System was being 

considered for secret and top secret radio-teletype communications, 

I was consulted and in view of my experience with all preceding t~letype encipherment systems was able to give technical approval 

on the new proposal and to insure that the production of keying tapes 

was properly safeguarded. 

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RE~_I_D: A60534 

~ EO 3. 3 • I h I I 2 I 

PL 86-36/50 USC 3605 

For a number of years prior to 1941 I had been m.ore or less 

intensively studying all the various cryptographic devi.ces and machines 

which had been invented and produced by private inventors both in the 

United States and in foreign countries. Files of patents issued 

domestically and abroad were kept, and theoretical studies made to 

ascertain the security of the products of invention in this field • 

.__~~~~~~~~~~~__.I This resulted in improvements in the security 

of the ma.chine and led finally to the adoption of Converter M-209 as 

a field instrument. Over 100,000 of them were manufactured, and used 

by both the Army and the Navy. While the machine was by no means 

perfect, it met a need that could hardly have been fulfilled otherwise. 

For a number of years I served on the Joint and the Combined Codes 

and Ciphers Committee and the Joint and Combined Security Committee. 

I was a member of a specialyAd Hoc Conunittee, consisting of two Navy 

officers, General (then Colonel) Corderman, and myself, appointed by 

the Joint Communications Board in 1944 to investigate the security of 

communications in all non-military bureaus and departments of the 

Government, making recommendations for improvement therein. The 

deliberations of the Ad Hoc Committee resulted in the establishment, 

by President Truman, of the Cryptographic Security Board for U. s. 

Government comm.unications, consisting of the Secretaries of the three 

Departments, State, War, and Navy. 

As technical adviser to the Chief, Signal Security Agency and to 

the Chief of the Security Division, I was constantly consulted by them 

in connection with the many problems affecting communications security. 

I also served in an advisory capacity in connection with all research 

and development of communications security equipment, including ciphony 

and cifax. One of my important contributions in this capacity was to 

urge the development of the voice security equipment, now known as the 

Sigsaly system, at a time when that project had been practically 

abandoned. 

The new Synchronous Polarity Reversal System of Cifax recently 

developed by us is based upon an invention of mine (Serial No. 478,193) 

filed on 3 June 1943 and assigned to the Secretary of War on 18 October 

19k3. Lieutenant Colonel nosen 1s invention of the important feature 

whereby the polarity reversals in the interaction of keying and picture 

elements are synchronized made the system practical and highly secure; 

in fact, there is reason to believe that the security of cifa.x transmissions by the Friedman-Rosen inventions can be made almost absolute. 

-sECRET 

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REF ID:A60534 • SECRET • 

In 1941 I undertook a study of the general basis of ~he distribution of Army cryptographic systems, evolving the new idea of "cryptonetsn, 

and thus improving security of conmunications. By isolating cryptographic 

systems according to levels of command and reducing the amount of intranet traffic •ti.thin any one system, the security of all systems is enhanced at the same time that provision is made for inter-net traffic. The 

cryptonet system has worked in a highly satisfactory manner in practice. 

B. Important Contributions !:.Q. Communications Intelligence, 1939-1945 

1. Solution of Japanese Diplomatic Communications.--On 20 February 1939 the Japanese Foreign Office began using a new machine called 

by them the 11B-Machine" for the highly secret communications between 

Tokyo and its embassies throughout the world. We had been successfully 

solving and reading practically all of the communications of the 

Japanese Foreign Office up to that time; many of them were in a machine 

( 11A Machine 11 ) which we had also solved and reconstructed by pure analysis 

in about the year 1937, but a large number were also in hand operated 

systems involving a small code, superenciphered by various schemes, 

usually transposition. 

The urgency of solution of the new macnine, in view of the 

increasingly difficult relations between the United States and Japan, 

wo.s apparent. However, in view of the small number of trained 

cryptanalysts available, the pressure of work in the sections operating on currently readable systems and in the sections producing our 

0111n codes, ciphers, and key lists, the number of people who could be 

placed on t!iis new and ve1 .. :: difficult problem was very limited. By 

August 1939, no important progress having been r.i.a.de, the Chief Signal 

Of.fj_cer direc•i.ed that I drop, so far as practicable,, certain administrative duties as assistant chief of Signal Intelligence Service (Major 

W. O. Reeder had been brought in as officer in charge in April 1938) 

and to participate actively in the studies of the 11B Ma.chine, 11 in 

addition to generally supervising Llle technical cryptanalytic and 

cryptographic work of the office. Thus, from that month until success 

was attained, the "B-Ma.chinen studies were under my active supervision 

but at the same time I had to carry on some other duties from which, 

it was impracticable to relieve me. 

By the end of 1939, the machine having been in use almost a full 

year, hundreds of messages had accumulated; very occasionally a tiny 

fragment of a message was read; rarely, longer fragments. But no messa~e was read in its entirety. Nevertheless important progress had 

been ma.de. Intensive work was continued by me and my technical staff 

SECRET 

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• REF ID:A60534 • 

of half a dozen cryptanalysts, with the clerical assistance of another 

half dozen people, and the occasional assistance of our two Japanese 

translators. On 20 September 1940 came the ve-ry first indication that 

we were on the right path and might be successful in solving the machine; 

under the pressure of great excitement, working almost day and night, 

by 27 September the first two translations representing the very first 

actual solution to the B-Machine were sent to G-2. 

There remained, hmvever, much work to be done, since only the 1

data 

applicable to but one out of the whole set of 120 indicators were at hand. 

By 14 October 1940 solutions for over one-third of the 120 indicators 

were available and certain current messages could be read .• 

By careful analytical reasoning, by studying the external 

cryptographic phenomena manifested by the system, by correct reasoning 

and a knowledge of c-ryptographic mechanisms, the principles underlying 

the cryptographic functioning of the B-Ma.chine were soon derived by 

induction and deduction. A hand-operated, crude model using flashlight bulbs \fas hurriedly constructed, while at the same time parts 

were ordered for two fully automatic, keyboard-operated machines, 

which were then constructed as rapidly as possible. All of this work 

also i.va.s under my general direction as Principal Cryptanalyst. By 

November 1940 the two fully automatic machines had been constructed 

and were in successful operation. We had, it is true, reconstructed 

the Japanese 11A-machine 11 by pure analysis, too, but so far as I am. 

aware, this is the first time in cryptanalytic history that a machine 

capable of deciphering traffic of the complexi...!-J: of that produced by 

the Japanese B-Machine was completely reconstructed by pure analysis. 

When we began the study we had no inkling as to the nature of the 

machine; soon thereafter we had ascertained that the cryptographic 

textual letters fell into two classes, but to this day we have never 

seen a complete Japanese machine in working order. Some time in 1942, 

long after our work of analysis had been completed, we did see the 

smashed, burned and almost unrecognizable remains of a B-Machine 

wnich the Japanese had destroyed on or about 5 December 1941 in 

Mexico and which remains came into possession of the F. B. I., who 

were anxious to reconstruct the machine if possible; also, and as 

a result 0£ European Ticorn operations, we did find two or three 

of the rotary-switch assemblies in a box taken from the ruins of the 

Japanese Embassy in Berlin, but or course these glimpses of one of 

the most important elements of the ma.chine were by this time only 

of academic interest. 

In January 1941 a Joint Army-l~avy Cryptanalytic Mission to GC 

and CS took with it one machine and a complete story of how to decipher 

diplomatic messages enciphered by the Japanese B-Machine. This 

system was one of the very few which had resisted all of GC and CS 

efforts to solve it. 

SECRET 

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"II ' ' .. 

.. _ 

REF ID:A60534 • SECi~ET ill., • 

As to the importance of the solution of the B-Ma.chine, or 

Purple System, as it was designated soon aft~r solution, I need 

only refer to the disclosureg of the current Joint Congressional 

Investigation of the att~ck on Pearl Harbor and to certain statements relative to the solution of the Japanese diplomatic machine 

contained in the letter dated 27 September 1944, which the Chief 

of Staff sent to Mr. Dewey, a copy of Vfhich is att<:1.ched hereto. ~Vhile that solution represents the achievement of a cooperative 

effort by a number of people, it was made possible by good coordination and proper technical direction of a fair number of skilled 

cryptanalytic personnel who w~re selected and trained by me and who 

worked under my direction for over 18 months as a harmonious team. 

In addition, certain of the cryptographic phenomena which ultimately 

led to the solution were uncovered by me in the course of those 

studies. A more detailed history of the solution is attached hereto. 

We kno11r that the German cryptanalytic staffs tried to solve 

the B-Machine and failed; as noted above, even as competent as was 

the British staff, it also failed to solve this machine and we gave them 

the solution. There is reason to believe that the Russian staff did not 

succeed, if they even undertook the problem, which we do not know. I 

belive it is true that as a result of our reading certain messages early 

in 1941 the State Department was able to give the Russian Government 

early information as to the co.ming secret offensive by the Germans, 

which began on 21 June 1941. Had the Russians been able to read the 

Purple, this would not have been necessary. As to the Japanese 

diplomatic communications in other systems, their messages in those 

systems were being read as promptly as facilities and personnel 

permitted, with priority being given those in the Purple System, 

although many important messages were also read in the various other 

systems, such as PA-K2, CA, and LA. 

2. GeneraJ..--As Heaa Cryptanalyst in the years 1939-1941, I 

was in technical charge of a staff of people numbering several thousand, 

working on all problems in the conununications intelligence field, and 

also supervised the selection and training of new personnel. Some of 

the problems being worked on during those years and successful in 

their outcome wer•3 those involving the diplomatic communications of 

several other governments than the Japanese such as the Italian, 

German, and Mexican. During the succeeding years, 1941-1945, the 

Agency accomplished many feats in cryptanalysis, too numerous to 

mention. 

The diplomatic coI!II!l.unications of many countries were read, 

some almost in toto; the communications of the Japanese Army and 

Air Force were read to a very large degree, contributing greatly to 

our victory in the Pacific. 

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SECRET • REF ID:A60534 

The extent to which the Agency engaged in the research, 

development, and use of high speed analytic equipments to facilitate the application of cryptanalytic techniques and processing 

is ltrorthy of mention and my technical advice and collaboration was 

used in all these cases. I was largely responsible for urging the 

development of the 11 003 11 equipment and had general supervision over 

its design, construction, and installation by the Bell Telephone 

Laboratories and the Western Electric Company. The fruits of that 

equip.ment and the modifications which followed and which were applied 

to the solution of German Enigma traffic represent some of the best 

achievements of the Agency. Our important developments in the field 

of photo-electric rapid analytical machinery also resulted from my 

insistence upon embarking upon such developments. In all these 

matters my advice was sought and obtained by the Chief of the Agency 

and special reports were prepared for him from time to time on these 

subjects. These equipments aided considerably in the solution of 

the diplomatic and military communications which were worked on by 

the Agency. 

SECRET 

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