Review of Clark
The Man Who Broke Purple by Ronald W. Clark. Weidenfeld and Nicolson
Cipher-breaking wins wars. The next global conflict could conveniently be decided (and perhaps already has been) by international competition among cryptologists. That would entail a team tournament, not single combat. Nowadays the work is done by committees and computers; the day of the individual key figure is over. The last and greatest of that distinguished line was William Friedman (1891-1969), born in Russia but naturalized American together with his emigré Jewish parents. He began his career 'as a geneticist – aptly, since later research was to show that life itself is transmitted by a genetic code. He then turned to cryptology as a result of being' employed by wealthy amateur to investigate one of - the so-called Shakespearean ciphers designed (no doubt sub‑consciously) by their exponents to reveal the true authorship and significance of the plays. This topic preoccupied Friedman for much of his life; but it was surely well beneath his notice, and his own bookThe Shakespearean Ciphers Examined (written jointly with his wife, herself an eminent cryptologist) is the classic case of using sledgehammers to crack nuts.
Colonel Friedman's genius was first manifested in his pioneer application of statistical disciplines (perhaps acquired in his study of genetics) to the process of cipher-breaking. This characteristic approach culminated in his leadership of a team which not only broke PURPLE (the code name given to the stupefyingly complex top security Japanese machine-cipher) but was also able to construct a working replica of the actual enciphering mechanism. Thus from August 1940 onwards, top secret messages from Tokyo were being read in Washington, and the balance of power was already tilting long before the Japanese attack on the United States naval base at Pearl Harbor and the subsequent declaration of war.
This example of an intellectual force capable of swaying the fate of great nations invites comparison with Einstein, whose biography Ronald Clark, author of The Man Who Broke Purple, has also written. But such high-level scientific minds will remain a sealed book to most readers; and in Friedman's case there are still many blank pages. His life and works are not merely private but top secret. He was (as Mr Clark now reveals) subject to recurrent bouts of depressive illness. He could never fully consult a psychiatrist, because his subconscious mind was a national security risk; his life was vowed to the most silent and secret of all services. In this book too he remains an enigma, not to say a cipher.
This is no fault of its author's. He is an experienced and accredited scientific biographer, who has worked hard at covering his great subject with the slender and intractable material available. He offers the first self-contained biographical and technical study of Friedman, and perhaps the first of any cryptologist. All the main known writings, achievements and interests are lucidly summarized in these carefully planned and competently written pages. So all cryptologists, amateur and professional, will wish to buy and read this book. But they should be warned of possible disappointments. The first and worst is the paucity of new and relevant material. In almost every significant respect, it seems to me, Ronald Clark has been anticipated by David Kahn (in that monumental compendium of cipher history and practice,The Codebreakers, 1969). This earlier source however is nowhere mentioned, and indeed seems to have been left unopened (otherwise Mr Clark's account of, for instance, the Ingo Denpo message of December 7, 1941 would surely have been different).
Further, the absence of fresh fact leaves too much room for profitless speculation. Thus it is heavily hinted more than once that Friedman's depressive illnesses were related to guilt-feelings about the nature of his profession and the use to which his discoveries had been put. This imputation, for which no very compelling evidence is offered, seems to me unfair to the memory of a great public servant. The depressions, in so far as they were exogenous, were surely activated by the inevitable frustrations of the cryptologist, such as the lack of informed recognition and the perpetual constraint of security regulations. A culminating affront was the confiscation, by the United States National Security Agency, of some fifty items from Friedman's personal cryptological collection kept in his own home and including several of his own seminal monographs. The lifelong feeling that a codebreaker cannot safely be left to his own devices is already unsettling enough, even discounting the innate predispositions of the obsessively introverted cryptological mind – that locked study from which one can never emerge unscathed without the key.
I infer from Mr Clark's text that he lacks personal experience of that cast of mind and its attendant disciplines and dichotomies; and there is a concomitant loss of empathy and vividness. The lightning flashes of Friedman's high-powered intuitive intellect result in some rather heavy weather. Yet there may be significant repercussions. It is now high time that other leading lights, e g of the British cryptographic service, had their achievements publicly recognized and documented. The mathematical genius of Alan Turing for example was comparable to Friedman's; he and his compeers also deserve the fullest commemoration.