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Kahn, David. Seizing the Enigma: The Race to Break the German U-Boat Codes, 1939-1943. Boston: Houghton Mifflin, 1991. London: Souvenir Press, 1991. New York: Barnes & Noble, 1998.

Kruh, Cryptologia 23.2, notes that the Barnes & Noble edition of "this superb book ... contains a new preface by Kahn, who also used the opportunity to correct some minor errors found in the earlier edition." In the view of Milner, I&NS 9.1, the author presents a "fascinating study ... and a perfectly sound conclusion." He has an "impressive grasp of the practical problems of codebreaking and usage ... [and] understands the limits of special intelligence."

For Surveillant 1.4, this is a "rare gem" of a book. It tells the "story of how the British, unable to break the German naval Enigma cipher machine because it was used in a much more complicated fashion than the Luftwaffe Enigma machine (which they were breaking), had to steal documents from some German weather ships operating north of Iceland, to aid in breaking the codes.... [W]ith these filched documents, [they] were able to break the German U-boat codes and divert their convoys so they wouldn't be sunk and, later, sink the U-boats because they now knew where they were located."

Miller, IJI&C 6.3, says that Kahn "presents another excellent work on intelligence and raises his standards even higher.... This remarkably fine book is the best to date on ULTRA." To Ringle, WPNWE, 17-23 Jun. 1991, the author's "impressive economy and dogged research" has produced "not only great history, but great midnight reading." Peake, AIJ 15.1/90, sees Seizing the Enigma as "a very readable and worthwhile book."

Kahn, David, ed. "From the Archives: Britain Reveals Its Bombe to America." Cryptologia 26, no. 2 (Apr. 2002): 124-128.

Memoranda from "C" (Admiral Sinclair) and Alastair Dennison make it clear that the early 1941 U.S. delegation was told of the existence of the bombes.

Kapera, Zdzislaw J., ed. Before Ultra There Was Gale: Some Contributions to the History of the Polish Enigma, 1939-1942. The Enigma Bulletin, No. 6. Mogilany, Poland: The Enigma Press, 2002.

Kruh, Cryptologia 27.4, notes that these essays come out of a conference on "The Contribution of Polish Intelligence to the Allied Victory in the Second World War," and mark the 70th anniversary (2002) of the breaking of the military Enigma by the Polish mathematician Marian Rejewski. This work provides "interesting reading about the vital role of the Polish Cipher Bureau in the Enigma battle."

Keegan, John. "The Product of Bletchley." Times Literary Supplement, 12 Oct. 1984, 1163-1164.

Sexton calls this an "[i]nsightful essay."

Keen, John. Harold "Doc" Keen and the Bletchley Park BOMBE. Cleobury Mortimer: M&M Baldwin, 2003.

Kesaris, Paul. ULTRA. Lanham, MD: University Publications of America, 1980. [Chambers]

Korbonski, Stefan. "The True Story of Enigma -- The German Code Machine in World War II." East European Quarterly 11 (Summer 1977): 227-234.

Sexton notes that by focusing on "the pioneering Polish contribution to the solution of ENIGMA," this article "[s]eeks to correct the impression that ULTRA was primarily an Anglo-American achievement."

Kozaczuk, Wladyslaw.

1. Ed. and tr., Christopher Kasparek. Enigma: How the German Machine Cipher Was Broken, and How It Was Read by the Allies in World War II. Frederick, MD: University Publications of America, 1984.

According to Pforzheimer, the author focuses on "the role of Polish cryptologists in breaking the early German (pre-World War II) Enigma ciphers." Kozachuk may "give his Polish compatriots more credit than perhaps they should receive, major though their early work was." This volume belongs "on the shelf of important books on the Ultra secret." Sexton finds the book to be a "valuable corrective to Bertrand and Winterbotham" and an "essential source." For brief excerpts from this work, see Wladyslaw Kozaczuk, "Enigma Solved," Cryptologia 6, no. 1 (Jan. 1982): 32-33.

2. and Jerzy Straszak. Enigma: How the Poles Broke the Nazi Code. New York: Hippocrene, 2004.

Foot, I&NS 20.3 (Sep. 2005), notes that the authors "make it clear how successful the Poles were in breaking the machine cipher the Germans thought impregnable.... This short book ... is eminently readable, and deserves study."

Kruh, Louis.

1. "British-American Cryptanalytic Cooperation and an Unprecedented Admission by Winston Churchill." Cryptologia 13, no. 2 (Apr. 1989): 123-134.

Included here is correspondence between Churchill and Roosevelt documenting that the British had decrypted American diplomatic traffic.

2. "Unlocking Enigma's Secrets." Cryptologia 14, no. 4 (Oct. 1990): 366-369.

Discusses a then-new exhibit at the Smithsonian Institution.

3. "Why Was Safford Pessimistic About Breaking the German Enigma Cipher Machine in 1942?" Cryptologia 14, no. 3 (Jul. 1990): 253 257.

According to Sexton, this article explores the "meaning of Captain Laurance F. Safford's remark of March 1942 that 'our prospects of ever breaking the German ENIGMA cipher machine are rather poor.'"

Leavitt, David. The Man Who Knew Too Much: Alan Turing and the Invention of the Computer. New York: Norton, 2006. London: Weidenfeld & Nicolson, 2006.

Kruh, Cryptologia 30.3 (Jul.-Sep. 2006), finds that the author "portrays Turing in all his humanity, his eccentricities, his brilliance, and his fatal candor while elegantly explaining his work and its implications." For Ferry, The Guardian, 29 Jul. 2006, the author presents Turing "as a lonely maverick, isolated by his fascination with machine intelligence and even more so by his homosexuality. For anyone daunted by Andrew Hodges's magisterial 1983 biography, on which he draws heavily, Leavitt provides a sympathetic novelist's take on a brilliant eccentric. But the supporting characters are curiously two-dimensional."

Lee, John A. N., and Golde Holtzman. "50 Years after Breaking the Codes: Interviews with Two of the Bletchley Park Scientists." IEEE Annals of the History of Computing 17, no. 1 (1995): 32-43.

Interviews with Irving John Good and Donald Michie.

Lemire, Laurent. Alan Turing: L'homme qui a croqué la pomme. Paris: Hachette littératures, 2004.

Lewin, Ronald.

1. "A Signals Intelligence War." Journal of Contemporary History 16 (Jul. 1981): 501-512. Also, in The Second World War: Essays in Military and Political History, ed. Walter Laqueur, 184-194. Beverly Hills, CA: SAGE, 1982.

Sexton sees this as an "insightful article in which the author endeavors to assess the impact of ULTRA."

2. ULTRA Goes to War: The First Account of World War II's Greatest Secret Based on Official Documents. London: Hutchinson, 1978. New York: McGraw Hill, 1978. New York: Pocket Books, 1980. [pb] New York: Penguin, 2001. [pb]

Peake, AIJ 5.1/90, calls ULTRA Goes to War "a good relatively short overview of how ULTRA was used in the European theater." According to Pforzheimer, "Lewin has had access to a considerable quantity of ... Ultra messages as well as to many Allied users as sources for his book. He makes a major contribution to World War II historiography in his study of the impact of the Ultra material on the major battles and campaigns of the war in the West."

Constantinides notes that the scope of the book "is largely British, and the areas are Europe, Africa, the Mediterranean, and the Atlantic Ocean." Worthy as it is of praise, this book is not perfect. Lewin's "version of the cryptanalytical breakthrough against Enigma, good as it is, has technical errors and cannot be regarded as definitive.... To say that the Purple machine was directly derived from the Enigma is not accurate."

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