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CONTENTS
Preface to the Revised Edition
Preface
A Few Words
1. One Day of Magic
THE PAGENT OF CRYPTOLOGY
2. The First 3,000 Years
3. The Rise of the West
4. On the Origin of a Species
5. The Era of the Black Chambers
6. The Contribution of the Dilettantes
7. Crises of the Union
8. The Professor, the Soldier, and the Man on Devil's Island
9. Room 40
10. A War of Intercepts: I
11. A War of Intercepts: II
12. Two Americans
13. Secrecy for Sale
14. Duel in the Ether: The Axis
15. Duel in the Ether: Neutrals and Allies
16. Censors, Scramblers, and Spies
17. The Scrutable Orientals
18. Russkaya Kriptologiya ("Russian Cryptology")
19. N.S.A.
SIDESHOWS
20. The Anatomy of Cryptology
21. Heterogeneous Impulses
22. Rumrunners, Businessmen, and Makers of Non-secret Codes
23. Ciphers in the Past Tense
24. The Pathology of Cryptology
PARACRYPTOLOGY
25. Ancestral Voices
26. Messages from Outer Space
THE NEW CRYPTOLOGY
27. Cryptology Goes Public
Bibliography
Notes to Text
Acknowledgments
Notes to Illustrations
Index
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ONE DAY OF MAGIC
At 1:28 on the morning of December 7, 1941, the big ear of the Navy's radio station on Bainbridge Island near Seattle trembled to vibrations in the ether. A message was coming through on the Tokyo-Washington circuit. It was addressed to the Japanese embassy, and Bainbridge reached up and snared it as it flashed overhead. The message was short, and its radiotelegraph transmission took only nine minutes. Bainbridge had it all by 1:37.
The station's personnel punched the intercepted message on a teletype tape, dialed a number on the teletypewriter exchange, and, when the connection had been made, fed the tape into a mechanical transmitter that gobbled it up at 60 words per minute.
The intercept reappeared on a page-printer in Room 1649 of the Navy Department building on Constitution Avenue in Washington, D.C. What went on in this room, tucked for security's sake at the end of the first deck's sixth wing, was one of the most closely guarded secrets of the American government. For it was in here -- and in a similar War Department room in the Munitions Building next door -- that the United States peered into the most confidential thoughts and plans of its possible enemies by shredding the coded wrappings of their dispatches.
Room 1649 housed OP-20-GY, the cryptanalytic section of the Navy's cryptologic organization, OP-20-G. The page-printer stood beside the desk of the GY watch officer. It rapped out the intercept in an original and a carbon copy on yellow and pink teletype paper just like news on a city room wire-service ticker. The watch officer, Lieutenant (j.g.) Francis M. Brotherhood, U.S.N.R., a curly-haired, brown-eyed six-footer, saw immediately from indicators that the message bore for the guidance of Japanese code clerks that it was in the top Japanese cryptographic system.
This was an extremely complicated machine cipher which American cryptanalysts called PURPLE. Led by William F. Friedman, Chief Cryptanalyst of the Army Signal Corps, a team of codebreakers had solved Japan's enciphered dispatches, deduced the nature of the mechanism that would effect those letter transformations, and painstakingly built up an apparatus that cryptographically duplicated the Japanese machine. The Signal Corps had then constructed several additional PURPLE machines, using a hodgepodge of manufactured parts, and had given one to the Navy. Its three components rested now on a table in Room 1649: an electric typewriter for input; the cryptographic assembly proper, consisting of a plugboard, four electric coding rings, and associated wires and switches, set on a wooden frame; and a printing unit for output. To this precious contraption, worth quite literally more than its weight in gold, Brotherhood carried the intercept.
He flicked the switches to the key of December 7. This was a rearrangement, according to a pattern ascertained months ago, of the key of December 1, which OP-20-GY had recovered. Brotherhood typed out the coded message. Electric impulses raced through the maze of wires, reversing the intricate enciphering process. In a few minutes, he had the plaintext before him.
It was in Japanese. Brotherhood had taken some of the orientation courses in that difficult language that the Navy gave to assist its cryptanalysts. He was in no sense a translator, however, and none was on duty next door in OP-20-GZ, the translating section. He put a red priority sticker on the decode and hand-carried it to the Signal Intelligence Service, the Army counterpart of OP-20-G, where he knew that a translator was on overnight duty. Leaving it there, he returned to OP-20-G. By now it was after 5 a.m. in Washington -- the message having lost three hours as it passed through three time zones in crossing the continent.
The S.I.S. translator rendered the Japanese as: "Will the Ambassador please submit to the United States Government (if possible to the Secretary of State) our reply to the United States at 1:00 p.m. on the 7th, your time." The -- "reply" referred to had been transmitted by Tokyo in 14 parts over the past 18' hours, and Brotherhood had only recently decrypted the 14th part on the PURPLE machine. It had come out in the English in which Tokyo had framed it, and its ominous final sentence read: "The Japanese Government regrets to have to notify hereby the American Government that in view of the attitude of the American Government it cannot but consider that it is impossible to reach an agreement through further negotiations." Brotherhood had set it by for distribution early in the morning.
The translation of the message directing delivery at one o'clock had not yet come back from S.I.S. when Brotherhood was relieved at 7 a.m., and he told his relief, Lieutenant (j.g.) Alfred V. Pering, about it. Half an hour later, Lieutenant Commander Alwin D. Kramer, the Japanese-language expert who headed GZ and delivered the intercepts, arrived. He saw at once that the all-important conclusion of the long Japanese diplomatic note had come in since he had distributed the 13 previous parts the night before. He prepared a smooth copy from the rough decode and had his clerical assistant, Chief Yeoman H. L. Bryant, type up the usual 14 copies. Twelve of these were distributed by Kramer and his opposite number in S.I.S. to the President, the secretaries of State, War, and Navy, and a handful of top-ranking Army and Navy officers. The two others were file copies. This decode was part of a whole series of Japanese intercepts, which had long ago been given a collective codename, partly for security, partly for ease of reference, by a previous director of naval intelligence, Rear Admiral Walter S. Anderson. Inspired, no doubt, by the mysterious daily production of the information and by the aura of sorcery and the occult that has always enveloped cryptology, he called it MAGIC.
When Bryant had finished, Kramer sent S.I.S. its seven copies, and at 8 o'clock took a copy to his superior, Captain Arthur H. McCollum, head of the Far Eastern Section of the Office of Naval Intelligence.
He then busied himself in his office, working on intercepted traffic, until 9:30, when he left to deliver the 14th part of Tokyo's reply to Admiral Harold F. Stark, the Chief of Naval Operations, to the White House, and to Frank Knox, the Secretary of the Navy. Knox was meeting at 10 a.m. that Sunday morning in the State Department with Secretary of War Henry L. Stimson and Secretary of State Cordell Hull to discuss the critical nature of the American negotiations with Japan, which, they knew from the previous 13 parts, had virtually reached an impasse. Kramer returned to his office about 10:20, where the translation of the message referring to the one o'clock delivery had arrived from S.I.S. while he was on his rounds.
Its import crashed in upon him at once. It called for the rupture of Japan's negotiations with the United States by a certain deadline. The hour set for the Japanese ambassadors to deliver the notification -- 1 p.m. on a Sunday -- was highly unusual. And, as Kramer had quickly ascertained by drawing a navigator's time circle, 1 p.m. in Washington meant 7:30 a.m. in Hawaii and a couple of hours before dawn in the tense Far East around Malaya, which Japan had been threatening with ships and troops.
Kramer immediately directed Bryant to insert the one o'clock message into the reddish-brown looseleaf cardboard folders in which the MAGIC intercepts were bound. He included several other intercepts, adding one at the last minute, then slipped the folders into the leather briefcases, zipped these shut, and snapped their padlocks. Within ten minutes he was on his way.
He went first to Admiral Stark's office, where a conference was in session, and indicated to McCollum, who took the intercept from him, the nature of the message and the significance of its timing. McCollum grasped it at once and disappeared into Stark's office. Kramer wheeled and hurried down the passageway. He emerged from the Navy Department building and turned right on Constitution Avenue, heading for the meeting in the State Department eight blocks away. The urgency of the situation washed over him again, and he began to move on the double.
This moment, with Kramer running through the empty streets of Washington bearing his crucial intercept, an hour before sleepy code clerks at the Japanese embassy had even deciphered it and an hour before the Japanese planes roared off the carrier flight decks on their treacherous mission, is perhaps the finest hour in the history of cryptology. Kramer ran while an unconcerned nation slept late, ignored aggression in the hope that it would go away, begged the hollow gods of isolationism for peace, and refused to entertain -- except humorously -- the possibility that the little yellow men of Japan would dare attack the mighty United States. The American cryptanalytic organization swept through this miasma of apathy to reach a peak of alertness and accomplishment unmatched on that day of infamy by any other agency in the United States. That is its great achievement, and its glory. Kramer's sprint symbolizes it.
Why, then, did it not prevent Pearl Harbor? Because Japan never sent any message saying anything like "We will attack Pearl Harbor." It was therefore impossible for the cryptanalysts to solve one. Messages had been intercepted and read in plenty dealing with Japanese interest in warship movements into and out of Pearl Harbor, but these were evaluated by responsible intelligence officers as on a par with the many messages dealing with American warships in other ports and the Panama Canal. The causes of the Pearl Harbor disaster are many and complex, but no one has ever laid any of whatever blame there may be at the doors of OP-20-G or S.I.S. On the contrary, the Congressional committee that investigated the attack praised them for fulfilling their duty in a manner that "merits the highest commendation."
As the climax of war rushed near, the two agencies -- together the most efficient and successful codebreaking organization that had ever existed -- scaled heights of accomplishment greater than any they had ever achieved. The Congressional committee, seeking the responsibility for the disaster, exposed their activity on almost a minute-by-minute basis. For the first time in history, it photographed in fine-grained detail the operation of a modern codebreaking organization at a moment of crisis. This is that film. It depicts OP-20-G and S.I.S. in the 24 hours preceding the Pearl Harbor attack, with the events of the past as prologue. It is the story of one day of MAGIC.
The two American cryptanalytic agencies had not sprung full-blown into being like Athena from the brow of Zeus. The Navy had been solving at least the simpler Japanese diplomatic and naval codes in Rooms 1649 and 2646 on the "deck" above since the 1920s. Among the personnel assigned to cryptan alytical duties were some of the Navy's approximately 50 language officers who had served in Japan for three years studying that exceedingly difficult tongue. One of them was Lieutenant Ellis M. Zacharias, later to become famous as an expert in psychological warfare against Japan. After seven months of training in Washington in 1926, he took charge of the naval listening station on the fourth floor of the American consulate in Shanghai, where he intercepted and cryptanalyzed Japanese naval traffic. This post remained in operation until it was evacuated to Corregidor in December, 1940. Long before then, radio intelligence units had been set up in Hawaii and in the Philippines, with headquarters in Washington exercising general supervision.
The Army's cryptanalytical work during the 1920s was centered in the so-called American Black Chamber under Herbert O. Yardley, who had organized it as a cryptologic section of military intelligence in World War I. It was maintained in secrecy in New York jointly by the War and State departments, and perhaps its greatest achievement was its 1920 solution of Japanese diplomatic codes. At the same time, the Army's cryptologic research and code-compiling functions were handled by William Friedman, then as later a civilian employee of the Signal Corps. In 1929, Henry L. Stimson, then Secretary of State, withdrew State Department support from the Black Chamber on ethical grounds, dissolving it. The Army decided to consolidate and enlarge its codemaking and codebreaking activities. Accordingly, it created the Signal Intelligence Service, with Friedman as chief, and, in 1930, hired three junior cryptanalysts and two clerks.
The following year, a Japanese general suddenly occupied Manchuria and set up a puppet Manchu emperor, and the government of the island empire of Nippon fell into the hands of the militarists. Their avarice for power, their desire to enrich their have-not nation, their hatred for white Occidental civilization, started them on a decade-long march of conquest. They withdrew from the League of Nations. They began beefing up the Army. They denounced the naval disarmament treaties and began an almost frantic shipbuilding race. Nor did they neglect, as part of their war-making capital, their cryptographic assets. In 1934, their Navy purchased a commercial German cipher machine called the Enigma; that same year, the Foreign Office adopted it, and it evolved into the most secret Japanese system of cryptography. A variety of other cryptosystems supplemented it. The War, Navy, and Foreign ministries shared the superenciphered numerical HATO code for intercommunication. Each ministry also had its own hierarchy of codes. The Foreign Office, for example, employed four main systems, each for a specific level of security, as well as some additional miscellaneous ones.
Meanwhile, the modern-style shoguns speared into defenseless China, sank the American gunboatPanay,raped Nanking, molested American hospitals and missions in China, and raged at American embargoes on oil and steel scrap. It became increasingly evident that Nippon's march of aggression would eventually collide with American rectitude. The mounting curve of tension was matched by the rising output of the American cryptanalytic agencies. A trickle of MAGIC in 1936 had become a stream in 1940. Credit for this belongs largely to Major General Joseph O. Mauborgne, who became Chief Signal Officer in October, 1937.
Mauborgne had long been interested in cryptology. In 1914, as a young first lieutenant, he achieved the first recorded solution of a cipher known as the Playfair, then used by the British as their field cipher. He described his technique in a 19-page pamphlet that was the first publication on cryptology issued by the United States government. In World War I, he put together several cryptographic elements to create the only theoretically unbreakable cipher, and promoted the first automatic cipher machine, with which the unbreakable cipher was associated. He was among the first to send and receive radio messages in airplanes. As Chief Signal Officer, he retained enough of his flair for cryptanalysis to solve a short and difficult challenge cipher. He was also talented in other directions: he played the violin well and was an accomplished artist, exhibiting at, among others, the Chicago Art Institute.
When he became head of the Signal Corps, he immediately set about augmenting the important cryptanalytic activities. He established the S.I.S. as an independent division reporting directly to him, enlarged its functions, set up branches, started correspondence courses, added intercept facilities, increased its budget, and put on more men. In 1939, when war broke out in Europe, S.I.S. was the first agency in the War Department to receive more funds, personnel, and space. Perhaps most important of all, Mauborgne's intense interest inspired his men to outstanding accomplishments. More and more codes were broken, and as the international situation stimulated an increasing flow of intercepts, the MAGIC intelligence approached flood stage.
Mauborgne retired in September, 1941, leaving an expanded organization running with smooth efficiency. By then the Japanese had completed the basic outline for a dawn attack on Pearl Harbor. The plan had been conceived in the fertile brain of Admiral Isoroku Yamamoto, Commander-in-Chief Combined Fleet, Imperial Japanese Navy. Early in the year, he had ordered a study of the operation, contending that "If we have war with the United States, we will have no hope of winning unless the United States fleet in Hawaiian waters can be destroyed." By May, 1941, studies had shown the feasibility of a surprise air attack, statistics had been gathered, and operational planning was under way.
In the middle of that month, the U.S. Navy took an important step in the radio intelligence field. It detached a 43-year-old lieutenant commander from his intelligence berth aboard U.S.S.Indianapolisand assigned him to reorganize and strengthen the radio intelligence unit at Pearl Harbor. The officer was Joseph John Rochefort, the only man in the Navy with expertise in three closely related and urgently needed fields: cryptanalysis, radio, and the Japanese language. Rochefort, who had begun his career as an enlisted man, had headed the Navy's cryptographic section from 1925 to 1927. Two years later, a married man with a child, he was sent, because of his outstanding abilities, as a language student to Japan, a hard post to which ordinarily only bachelor officers were sent. This three-year tour was followed by half a year in naval intelligence; most of the next eight years were spent at sea.
Finally, in June of 1941, Rochefort took over the command of what was then known as the Radio Unit of the 14th Naval District in Hawaii. To disguise its functions he renamed it the Combat Intelligence Unit. His mission was to find out, through communications intelligence, as much as possible about the dispositions and operations of the Japanese Navy. To this end he was to cryptanalyze all minor and one of the two major Japanese naval cryptosystems.
His chief target was the flag officers' system, the Japanese Navy's most difficult and the one in which it encased its most secret information. From about 1926 to the end of November, 1940, previous editions had provided the U.S. Navy with much of its information on the Japanese Navy. But the new version -- a four-character code with a transposition superencipherment -- was stoutly resisting the best efforts of the Navy's most skilled cryptanalysts, and Rochefort was urged to concentrate on it. The other major system, the main fleet cryptographic system, the most widely used, comprised a code with five-digit codenumbers to which were added a key of other numbers to complicate the system. The Navy called it the "five numeral system," or, more formally, JN25b -- the JN for "Japanese Navy," the 25 an identifying number, the b for the second (and current) edition. Navy cryptanalytic units in Washington and the Philippines were working on this code. Rochefort's unit did not attack this but did attack the eight or ten lesser codes dealing with personnel, engineering, administration, weather, fleet exercises.
But cryptanalysis was only part of the unit's task. The great majority of its 100 officers and men worked on two other aspects of radio intelligence -- direction-finding and traffic analysis.
Direction-finding locates radio transmitters. Since radio signals are heard best when the receiver points at the transmitter, sensitive antennas can find the direction from which a signal is coming by swinging until they hear it at its loudest. If two direction-finders take bearings like that on a signal and a control center draws the lines of direction on a map, the point at which they cross marks the position of the transmitter. Such a fix can tell quite precisely where, for example, a ship is operating. Successive fixes can plot its course and speed.
To exploit this source of information, the Navy in 1937 established the Mid-Pacific Strategic Direction-Finder Net. By 1941, high-frequency direction-finders curved in a gigantic arc from Cavite in the Philippines through Guam, Samoa, Midway, and Hawaii to Dutch Harbor, Alaska. The 60 or 70 officers and men who staffed these outposts reported their bearings to Hawaii, where Rochefort's unit translated them into fixes. For example, on October 16, the ship with call-sign KUNA 1 was located at 10.7 degrees north latitude, 166.7 degrees east longitude -- or within Japan's mandated islands.
These findings did not serve merely to keep an eye on the day-to-day locations of Japanese warships. They also formed the basis of the even more fruitful technique of traffic analysis. Traffic analysis deduces the lines of command of military or naval forces by ascertaining which radios talk to which. And since military operations are usually accompanied by an increase in communications, traffic analysis can infer the imminence of such operations by watching the volume of traffic. When combined with direction-finding, it can often approximate the where and when of a planned movement.
Radio intelligence thus maintains a long-range, invisible, and continuous surveillance of fleet movements and organization, providing a wealth of information at a low cost. Of course it has its limitations. A change of the call-signs of radio transmitters can hinder it. The sending of fictitious messages can befuddle it. Radio silences can deafen it. But it cannot be wholly prevented except by unacceptable restrictions on communications. Hence the Navy relied increasingly on it for its information on Japanese naval activities as security tightened in Japan during 1941, and almost exclusively after July, when the President's trade-freezing order deprived the Navy of all visual observations of Japanese ships not on the China coast.
It was in July that a Japanese tactic set up a radio pattern that was later to deceive the Combat Intelligence Unit. The Nipponese militarists had decided to take advantage of France's defeat and occupy French Indochina. The naval preparations for the successful grab were clearly indicated in the radio traffic, which went through the usual three stages that preceded major Japanese operations. First appeared a heavy flurry of messages. The Commander-in-Chief Combined Fleet busily originated traffic, talking with many commands to the south, thereby indicating the probable direction of his advance. Then came a realignment of forces. In the lingo of the tranalysis people, certain chickens (fleet units) no longer had their old mothers (fleet commanders). Call-sign NOTA 4, which usually communicated with OYO 8, now talked mostly with ORU 6. Accompanying this was a considerable confusion in the routing of messages, with frequent retransmissions caused by the regrouping: Admiral Z not here; try Second Fleet. Then followed the third phase: radio silence. The task force was now under way. Messages would be addressed to it, but none would emanate from it.
During all this, however, not only were no messages heard from the aircraft carriers, none were sent to them, either. This blank condition exceeded radio silence, which suppresses traffic in only one direction -- from the mobile force -- not in both. American intelligence reasoned that the carriers were standing by in home waters as a covering force in case of counterattack, and that communications both to and from them were not heard because they were being sent out by short-range, low-powered transmissions that died away before reaching American receivers. Such a blank condition had obtained in a similar tactical situation in February. American intelligence had drawn the same conclusions then and had been proven right. Events soon confirmed the July assessment as well. Twice, then, a complete blank of carrier communications combined with indications of a strong southward thrust had meant the presence of the carriers in Empire waters. But what happened in February and July was not necessarily what would happen in December.
During the summer and fall of 1941, the pressure of events molded America's two cryptanalytic agencies closer and closer to the form they were to have on December 7. The Signal Intelligence Service, which had 181 officers, enlisted men, and civilians in Washington and 150 at intercept stations in the field on Pearl Harbor Day, had been headed since March by Lieutenant Colonel Rex W. Minckler, a career Signal Corps officer. Friedman served as his chief technical assistant. S.I.S. comprised the Signal Intelligence School, which trained Regular Army and Reserve officers in cryptology, the 2nd Signal Service Company, which staffed the intercept posts, and four Washington sections of the S.I.S. proper: the A, or administrative, which also operated the tabulating machinery; the B, or cryptanalytic; the C, or cryptographic, which prepared new U.S. Army systems, studied the current systems for security, and monitored Army traffic for security violations; and the D, or laboratory, which concocted secret inks and tested suspected documents.
The B section, under Major Harold S. Doud, a West Point graduate, had as its mission the solution of the military and diplomatic systems not only of Japan but of other countries. In this it apparently achieved at least a fair success, though no Japanese military systems -- the chief of which was a code employing four-digit codenumbers -- were readable by December 7 because of a paucity of material. Doud's technical assistant was a civilian, Frank B. Rowlett, one of the three original junior cryptanalysts hired in 1930. The military man in charge of Japanese diplomatic solutions was Major Eric Svensson.
The Navy's official designation of OP-20-G indicated that the agency was the G section of the 20th division of OPNAV, the Office of the Chief of Naval Operations, the Navy's headquarters establishment. The 20th division was the Office of Naval Communications, and the G section was the Communication Security Section. This carefully chosen name masked its cryptanalytic activities, though its duties did include U.S. Navy cryptography.
Its chief was Commander Laurence F. Safford, 48, a tall, blond Annapolis graduate who was the Navy's chief expert in cryptology. In January, 1924, he had become the officer in charge of the newly created research desk in the Navy's Code and Signal Section. Here he founded the Navy's communication-intelligence organization. After sea duty from 1926 to 1929, he returned to cryptologic activities for three more years, when sea duty was again made necessary by the "Manchu" laws, which required officers of the Army and Navy to serve in the field or at sea to win promotion. He took command of OP-20-G in 1936. One of his principal accomplishments before the outbreak of war was the establishment of the Mid-Pacific Strategic Direction-Finder Net and of a similar net for the Atlantic, where it was to play a role of immense importance in the Battle of the Atlantic against the U-boats.
Safford's organization enjoyed broad cryptologic functions. It printed new editions of codes and ciphers and distributed them, and contracted with manufacturers for cipher machines. It developed new systems for the Navy. It comprehended such subsections as GI, which wrote reports based on radio intelligence from the field units, and GL, a record-keeping and historical-research group. But its main interest centered on cryptanalysis.
This activity was distributed among units in Washington, Hawaii, and the Philippines. Only Washington attacked foreign diplomatic systems and naval codes used in the Atlantic theater (primarily German). Rochefort had primary responsibility for the Japanese naval systems. The Philippines chipped away at JN25 and did some diplomatic deciphering, with keys provided by Washington. That unit, which like Rochefort's was attached for administrative purposes to the local naval district (the 16th), was installed in a tunnel of the island fortress of Corregidor. It was equipped with 26 radio receivers, apparatus for intercepting both high- and low-speed transmissions, a direction-finder, and tabulating machinery. Lieutenant Rudolph J. Fabian, 33, an Annapolis graduate who had had three years of communication intelligence in Washington and the Philippines, commanded. The 7 officers and 19 men in his cryptanalytic group exchanged possible recoveries of JN25b codegroups with Washington and with a British group in Singapore; each group also had a liaison man with the other.
Of the Navy's total radio-intelligence establishment of about 700 officers and men, two thirds were engaged in intercept or direction-finding activities and one third -- including most of the 80 officers -- in cryptanalysis and translation. Safford sized up the personnel of his three units this way: Pearl Harbor had some of the best officers, most of whom had four or five years of radio intelligence experience; the crew at Corregidor, which in general had only two or three years' experience, was "young, enthusiastic, and capable"; Washington -- responsible for both overall supervision and training -- had some of the most experienced personnel, with more than ten years' experience, and many of the least: 90 per cent of the unit had less than a year's experience.
Under Safford in the three subsections most closely involved with cryptanalysis were Lieutenant Commanders George W. Welker of GX, the intercept and direction-finding subsection, Lee W. Parke of GY, the cryptanalytical subsection, and Kramer of GZ, the translation and dissemination subsection. GY attacked new systems and recovered new keys for solved systems, such as PURPLE. But while it made the initial breaks in code solutions, the detailed recovery of codegroups (which was primarily a linguistic problem as compared to the more mathematical cipher solutions) was left to GZ. Four officers in GY, assisted by chief petty officers, stood round-the-clock watches. Senior watch officer was Lieutenant (j.g.) George W. Lynn; the others were Lieutenants (j.g.) Brotherhood, Pering, and Allan A. Murray. GY had others on its staff, such as girl typists who also did the simple deciphering of some diplomatic messages after the watch officers and other cryptanalysts had found the keys.
Kramer was in an odd position. Though he worked in OP-20-GZ, he was formally attached to OP-16-F2 -- the Far Eastern Section of the Office of Naval Intelligence. This arrangement was intended in part to throw off the Japanese, who might have inferred some measure of success in codebreaking if a Japanese-language officer like Kramer were assigned to communications, in part to have an officer with a broad intelligence background distribute MAGIC so that he could answer the recipients' questions. Kramer, 38, who had studied in Japan from 1931 to 1934, had had two tours in O.N.I. proper before being assigned full time to GZ in June, 1940. An Annapolis graduate, chess fan, and rifle marksman, he lived in a world in which everything had one right way to be done. He chose his words with almost finicky exactness (one of his favorites was "precise"); he kept his pencil mustache trimmed to a hair; he filed his papers tidily; he often studied his MAGIC intercepts several times over before delivering them. Included in this philosophy was his duty. He performed it with great responsibility, intelligence, and dedication.
The first task of OP-20-G and of S.I.S. was to obtain raw material for the cryptanalysts. And in peacetime America that was not easy.
Section 605 of the Federal Communications Act of 1934, which prohibits wiretaps, also prohibits the interception of messages between for
Excerpted from The Codebreakers: The Comprehensive History of Secret Communication from Ancient Times to the Internet by David Kahn
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