Hoover was careful not to add that the actual content of the first dot the FBI saw was a copy of the German questionnaire.
Where is the truth in all this? Certainly Popov, writing decades after the events, slipped up on some details and may well have embellished the account. But reading the questionnaire today in the context of what Popov and the British were trying to convey does raise the question of how those references to Hawaii and to Pearl Harbor could have failed, somewhere along the line of recipients, to set off alarm bells.
The FBI did, Montagu has written, use Tricycle's name in sending messages to his spymaster. But they were "low-grade, trumpery stuff that almost any half-witted agent could have got." Further, "It is almost impossible to believe—they never let Tricycle know what they had sent or what the Germans had asked." At the Twenty Committee's request, Popov was allowed to return to Britain and in "the greatest instance of coldblooded courage that I have ever been in contact with" he met with his spy-master in Lisbon, explained away his American failures and again became a key member of the committee.
Postwar events also show that Popov's British masters did not share Hoover's disdain of him. Hinsley rates him as one of the three "most valuable" double agents in Britain's cause. In recognition of the daring and dangerous but vitally important work he carried out, the British promoted him to the honorary rank of colonel, granted him British citizenship and awarded him both the Distinguished Service Medal and the Order of the British Empire.
Jebsen, however, was arrested by the Gestapo, for reasons that are not clear. This was a development of great concern to the Twenty Committee because of what he could reveal. But he was killed, presumably trying to escape, and honorably carried his secrets with him.
Amid all the controversies swirling around Popov, this is for certain: he went to his grave believing that J. Edgar Hoover was "the person responsible for the disaster at Pearl Harbor."
8
The U.S. Tackles Japan's Codes
When Secretary of State Stimson sniffed at the idea of reading other gentlemen's mail and closed down Herbert Yardley's Black Chamber, American cryptology seemed to have come to an end. It had not. Quietly, other agencies, from the FBI and the Federal Communications Commission to the army and navy, carried on the task, independently of each other and often involving rancorous internecine turf wars.
Inheriting Yardley's files, the U.S. Army Signal Corps in 1930 created the Signal Intelligence Service (SIS). To head it up, the corps hired William Friedman, whom many consider the greatest cryptologic genius of all time.
Friedman came to code work by a serendipitous route. Born in Russia in 1891, he was brought to the U.S. as an infant. His family settled in Pittsburgh, and as a high school youth, he became caught up in a Jewish "back to the land" movement which led him, when he was a graduate student at Cornell University, to plan a career in plant genetics. In 1915 an eccentric millionaire cotton merchant named George Fabyan went to Cornell in search of a geneticist to work at his Riverbank Laboratory, near Chicago, on improving crop strains. Friedman, recommended by one of his professors, became head of Riverbank's Department of Genetics and involved himself in such Fabyan projects as planting oats by the light of the moon to see whether the phases made any difference in their growth.
Fabyan, who had the wealth to support his flights of fancy, also became intrigued by a woman whose research had convinced her that Francis Bacon had written the works attributed to William Shakespeare and, what was more, had included coded messages to that effect in the early folios of the plays and poems. She claimed the secret messages also revealed that he was the illegitimate son of Queen Elizabeth I and the rightful heir to the British throne. To fill out his team conducting this research, Fabyan hired Elizebeth Smith, a Hillsdale College graduate, whose mother had insisted on the unusual spelling of her name to prevent its being shortened to Eliza.
The theory of the Bacon codes was based on variations in the typefaces in the folios. Handy with a camera, Friedman helped the project by making photo enlargements of the type fonts. He was drawn to the cryptographic work. "Something in me," he commented later, "found an outlet."
Since Europe was then at war and American military involvement was becoming increasingly likely, Elizebeth and William foresaw the need for the U.S. to become more proficient in secret communications. Ever the opportunist, Fabyan enthusiastically supported this new phase of their research. For a time Riverbank was the only organization in the country skilled in deciphering coded messages. Their mutual professional and personal interests led Elizebeth and William to marriage in 1917.
When, later that year, the army created its Cipher Bureau, Fabyan arranged for the Friedmans to conduct classes in cryptography for army officers. A famous photo from that era shows Elizebeth and William surrounded by their eighty bright young students in khaki. The students' faces are turned either directly toward the camera or away from it to register a bilateral coded message: Bacon's aphorism "Knowledge is power."
As texts for his classes, Friedman began writing a series of booklets on cryptography—one of them with Elizebeth as collaborator. Impressed, the army brass offered him a first lieutenant's commission. He spent the last five months of World War I on General Pershing's staff in France, concentrating on breaking German codes. The experience gave him ideas that subsequently he was to use with great effect. On his return to Riverbank he published a new booklet, The Index of Coincidence and Its Application to Cryptography. David Kahn has written that it "must be regarded as the most important single publication in cryptology. It took the science into a new world."
Cryptanalysis had, previously, been rather an occult process in which the would-be breaker pored over a ciphertext waiting for some intuitive insight to lead to a solution. Friedman's "new world" consisted of methodically applying a statistical and mathematical science to codebreaking. His new booklet added a useful technique. He had observed that if the horizontal lines of a message are arranged so that the letters are placed in vertical rows precisely below each other, now and then the same letter will appear, the one directly beneath the other. This coincidence, he had determined, will vary in frequency with each language. In English it occurs in 6.67 columns of every 100. This was a step forward in cryptanalysis that gave Friedman a tool in analyzing the new machine-encoded ciphers when they began to appear.
During the 1920s both Friedmans were engaged in code work for the government. William made national headlines when he cracked the codes of the conspirators in the Teapot Dome scandal and helped send several of them to prison. He also became chief codebreaker for the War Department, where he developed the reputation of being like Midas, except that everything he touched turned not into gold but into plaintext. Elizebeth, in addition to starting a family, helped the Department of Justice and later the Treasury Department in efforts to enforce Prohibition. She broke the increasingly sophisticated codes of the rum-running syndicate and testified against them in well-publicized court cases.
When, in the autumn of 1929, William became chief of the newly created Signal Intelligence Service, he was empowered to begin building a cryptographic staff. He requested mathematicians, and chance gave him Frank Rowlett, a high school mathematics teacher from Virginia, and two graduate mathematicians from the City College of New York, Solomon Kullback and Abraham Sinkov. Also foreseeing the need for a translator fluent in Japanese, Friedman was swayed by a congressman to hire his nephew, John Hurt.
There were only five of them, but what a team they turned out to be! Friedman adroitly challenged his staff, first by having them study his cryptography writings, then by giving them relatively easy ciphers before moving on to more difficult examples. He threw at them a Great War German cipher that he, with a French cryptanalyst, had had considerable trouble in cracking. The team surprised him by the speed with which they broke it. He turned them loose on the Hebem mechanical enciphering device, which had taken him six weeks of intense concentration to solve; they broke it in less than
a month. They were ready, Friedman decided, to take on "real work": breaking the Japanese nonmachine "pencil and paper" codes then current. To Hurt's delight the cryptographers were soon giving him plaintext to translate and interpret. Sinkov recalled of Friedman, "His teaching was such that we developed on our own."
The second heavy responsibility placed on the Friedman five has already been mentioned: the work of developing secure cryptographic systems for the U.S. that resulted in the Sigaba M-134. Because of security restrictions, Friedman couldn't reveal even to his own lawyers the nature of the patents he was seeking. He had to write his own briefs.
Conquest of the Red Machine
As the 1930s unfolded, Friedman and his SIS team faced the challenge of breaking into the code machines the Japanese Foreign Office had introduced. First to be tackled was the Type A machine, the Alphabetical Typewriter 91.
Rowlett, in his memoir, The Story of Magic, gave a progressive account of how the Friedman team analyzed the Japanese machine and slowly solved it. They began by observing a quirk in the system. In their new machine ciphers the Japanese used the Roman alphabet to spell out phonetic equivalents of Japanese words, and in this new machine cipher, six letters occurred with high frequency, while the other twenty appeared less frequently. Friedman and his young analysts determined that the six consisted of the five vowels plus the letter V. The SIS was able to exploit this discovery by looking for patterns. One such pattern was that in the Japanese phonetics the Y was always followed by one of the other vowels and often by a doubling of them—YUU or YOO—and it was often preceded by R or K—RYUU, RYOO, KYUU, KYOO. Another pattern was the combination of the letters that, when deciphered, produced oyobi, the Japanese word for the English "and." In their analysis the Friedman crew noticed that their descriptions of these identifiable combinations held for only forty-two positions; then the machine introduced a stepping pattern, moving the whole process forward to a new equivalent of the letters. From those beginnings they were able gradually to open up the entire encoding system and produce plaintext from the messages.
Type A, they decided, was a rotor machine, a Japanese variation on the principles of the Enigma. Its encipherment mechanism included two rotors, each of which had twenty-six electrical contacts wired around the circumference of one of its sides. There was also a gear wheel with forty-seven pins projecting from it. A unique feature was that the gear wheel pins were removable. If a pin was in place, it moved the rotors forward with one stroke of the typewriter keys. If it was removed, the machine jumped over that contact, giving the machine an irregular movement meant to foil cryptanalysts.
The machine simply didn't have enough complexity to withstand the SIS team's attack. They were able gradually to open up the entire encoding system and produce plaintext from Type A's messages.
While solving its riddles, the cryptanalysts referred to it often as "the Japanese code machine." They realized that this term was so descriptive that its use might result in an inadvertent security break. They gathered together to settle on a cover name, and eventually the discussion got around to considering colors. "All of us were in agreement," Rowlett wrote, "that the first color of the spectrum was an excellent choice as a cover name for the first cipher machine that we had solved which was actually used for enciphering official messages of a foreign power. And from this moment on, the Japanese diplomatic cipher machine was always referred to as the 'Red Machine.'"
In short order the five team members began to flood the president, the secretary of state and the chiefs of the army and navy with John Hurt's translations of Japanese diplomatic exchanges. Friedman, incidentally, had overcome the usual interservice animosities and developed a friendly, mutually beneficial collaboration with Commander Laurance F. Safford, his counterpart in charge of the navy cryptologists.
Appreciation of the team's exploits took the practical form of increased funding for IBM processing machines, a move to more spacious quarters and an increased staff, including the hiring of bright young women such as Genevieve Grotjan.
The Breaking of Purple
In late 1938 and early 1939, Friedman and his expanded team began deciphering Red messages announcing the distribution of Red's replacement, angoo-ki taipu B, or "cipher machine Type B." They hoped that the new machine would be only a modification of Red, but a new series of messages sent in by U.S. intercept stations beginning on March 20, 1939, dashed that hope. They proved unbreakable by the methods applied to Red cryptanalysis.
As the Americans were to learn, slowly and painfully, Japanese cryptographers had built on their experience with Red and had perfected a machine whose principles were completely different from those in the German Enigma or other code machines and presented complexities greater than those of the Enigma.
Again Friedman met with his team to choose a new cover name. Sticking to the light spectrum, they chose the color Purple.
Ronald Clark, in his biography of Friedman, The Man Who Broke Purple, told of the felicitous decision made early in 1939 by General Joseph O. Mauborgne, chief of the Signal Corps. Disturbed by the slow progress being made in solving the Purple machine, Mauborgne saw that Friedman was too burdened by administrative details and work on the Sigaba to be effective in the attack. In February 1939, consequently, he ordered Friedman to drop all other duties and concentrate on Purple cryptanalysis. "Friedman," wrote Clark, "now began the most acute eighteen months of intellectual effort he was ever to undertake."
Rowlett's memoir suggested that Friedman had much less to do with the cracking of Purple than did Rowlett and other members of the SIS. However it was, progress did come at a brisker pace. Japanese errors helped. Reliance on ceremonial diplomatic forms of address such as "I have the honor to inform your excellency" handed the analysts cribs of probable plaintext to test against the ciphertext. Purple messages sent to embassies equipped only with the Red machine were obligingly repeated in that code, offering another angle from which to unravel the cipher. And on occasion a sender would admit having erred in one of his settings and re-send the message correctly, supplying the analysts with an insight into the proper setting.
Exacting analysis also showed that Purple offered the same structural opening as Red. Its system included a subsequence of six often-used letters enciphered separately from the other twenty. Unlike in the Red, though, these six could include any letter rather than just the vowels plus V. Rowlett drew up plans for a machine that would be an equivalent of the mechanism the Japanese used for enciphering and deciphering the sixes. Friedman, impressed with the plan, recommended that SIS employ Captain Leo Rosen, who had joined the Reserve Officer Training Corps at MIT while studying to become an electrical engineer.
The hiring of Rosen turned out to be another fortunate choice. Very quickly after being briefed on the nature of the Purple machine and of Rowlett's plan for cracking the sixes, he saw what was needed. This was nothing more than the use of standard telephone switchboard stepping switches. The switches were acquired, the "Six Buster" machine was built, and it did its job perfectly.
One of Safford's cooperating navy analysts, young Harry L. Clark, has been credited with raising the question of whether the Japanese, in their new machine, might be using an entirely different enciphering mechanism than those of other code machines. Could it be that the machine was based on the same stepping switches Rosen had applied in the Six Buster? Rowlett, Rosen and the others thought so, but before that question could be answered they had to gain a great deal more knowledge about the groups of twenty letters. Being able to tell where the sixes' letters occurred in a message helped by pinning down likely cribs. What was needed was a much broader base of plaintext equivalents of the twenties. The team made up large worksheets on which they recorded from each day's intercepts the most probable pairings of plaintext and ciphertext equivalents.
The process took most of a painstaking year. Then Genevieve "Gene" Grotjan, who had been doing the monotonous task of compiling indicator worksheets, made the breakthrough. R
owlett has described being in his office conferring with colleagues Bob Ferner and Albert Small when Grotjan broke in, visibly excited. She wanted to show them something in her worksheets. Leading them to her desk, she indicated where she had drawn circles around selected plaintext and ciphertext equivalents. Further, she had circled the same relationships on other worksheets. What she had found were consistent relationships, proofs that the coded letters were invariably linked with the plaintexts. As Rowlett characterized her discovery, it was "the first case of positive evidence that we were on the proper course to a full recovery of the Purple machine."
After she had pointed to the last example, Rowlett recalled, "she stepped back from her desk, with her eyes beaming through her rimless glasses, obviously thrilled by her discovery." The others immediately realized the importance of what she had found. "It was a beautiful example," Rowlett wrote, "of what we had hoped our search would uncover."
He described what followed: "Small promptly started dancing around her desk, raising his arms like a victorious prizefighter, and yelled 'Whoopee.' Ferner, who was usually very quiet and not very much inclined to show enthusiasm, clapped his hands, shouting 'Hurrah! Hurrah!' I could not resist jumping up and down and waving my arms above my head and exclaiming 'That's it! That's it! Gene has found what we've been looking for!'"
They made so much noise that Friedman came out of his office and asked, "What's this all about?"
Codebreakers Victory Page 15