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The Hagelin M-209 was a mechanical encryption device used by the U.S. Army during World War 2 (WWII) and the Korean War, as well as by other armies and diplomatic services. The Hagelin M-209 has been the focus of extensive research by codebreaking agencies. Several ciphertext-only attacks have been published, but, those attacks are applicable only to the case of long cryptograms. In this article, the authors present a nested hill-climbing and simulated annealing algorithm for recovering the full key settings from ciphertext only, with ciphertexts as short as 500 letters, compared to a minimum of 750 to 1,250 letters with prior methods. With this method, the authors have solved the last problem of a public Hagelin M-209 challenge contest. [ABSTRACT FROM AUTHOR]

World War II proved the value of using mathematicians as codebreakers. Both the Army’s Signal Intelligence Service (SIS) and the Navy’s OP-20-G recruited mathematicians. When the war ended and demobilization occurred, some of these mathematicians accepted academic positions or positions in industry, but some continued to serve as codebreakers. In the early 1950s, the Armed Forces Security Agency (AFSA) struggled with Soviet ciphers and with the United States’ communications intelligence (COMINT) needs for the Korean War. In 1951, in the face of a seemingly intractable problem with a Soviet cipher machine called Albatross, AFSA established a group of consultants, the Special Cryptologic Advisory Group (SCAG), which consisted of academic and industrial mathematicians and engineers. The year-long experience with SCAG led, in 1952, to AFSA’s establishment of a summer program, Special Committee Advising on Mathematical Problems (SCAMP), which enlisted academic mathematicians to work on Agency problems, and it also led to the establishment of the NSA Scientific Advisory Board (NSASAB). This article explores the immediate post-World War II evolution of the relationship between academic mathematicians and the NSA that is reflected in SCAG and in the beginnings of SCAMP and NSASAB. [ABSTRACT FROM PUBLISHER]

The Hagelin M-209 was a mechanical encryption device used by the U.S. Army during World War II and the Korean War, as well as by other armies and in embassy settings. In this article, the authors present a four-stage hillclimbing algorithm for recovering the full key settings from ciphertext only. The first two stages are based on a divide-and-conquer approach developed by Geoff Sullivan. In the current performance evaluation, the authors show that their method is able to recover key settings from messages as short as 750 letters, compared to 2,000 – 2,500 letters with prior methods. With this method, they solved several M-209 ciphertext-only challenges, including the final exercises in W. Barker’s 1977 book,Cryptanalysis of the Hagelin Cryptograph. [ABSTRACT FROM AUTHOR]

The author describes the ensuing developments from two now well-known publications in the twentieth century. They contained significant and seminal technological results: a paper by Claude Shannon in 1948 and a patent by Horst Feistel in 1971. Shannon announced the scope at the start, writing, “The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected *sent at another point” [55, p. 379]. Shannon's coding theorem established the relationship between the probability of receiving the message in error and transmission rate measuring the process efficiency. Shannon proved the existence of codes achievingoptimalperformance, but it required 45 years to exhibit an actual code achieving it. The optimal-efficient Shannon codes are responsible for a wide range of communication technology we enjoy today, from GPS to the NASA roversSpiritandOpportunityon Mars, and also to worldwide communication over the Internet. U.S. Patent #3798539A filed by the IBM Corporation in 1971 described Horst Feistel'sblock cipher cryptographic system, a new paradigm for encryption systems. It was a departure from the current cryptographic technology based on shift-register stream encryption for voice and the variety of the electromechanical cipher machines introduced nearly 50 years before. Horst's vision was its application to secure the privacy of computer files. It was invented at a propitious moment in time and implemented by IBM inautomated teller machinesfor the Lloydsbank cashpoint system. The emergence of e-commerce in the next decades would far overshadow the value of encryption in banking business. Finally, it has drastically altered the SIGINT mission of the National Security Agency. While Horst Feistel did not directly participate to any of these commercial applications of cryptography, the traditional interpretation of thelaw of cause and effectcertainly describes the effect of Feistel's patent. [ABSTRACT FROM PUBLISHER]

This article reports on the dedication of the Elizebeth Smith Friedman auditorium at the Washington DC headquarters of the ATF. [ABSTRACT FROM AUTHOR]

Noted author David Kahn has donated his lifetime collection of books, cryptologic artefacts and memorabilia to the National Cryptologic Museum. [ABSTRACT FROM AUTHOR]

Skipjack is a block cipher designed by the NSA for use in US government phones, and commercial mobile and wireless products by AT&T. Among its initial implementations in hardware were the Clipper chip and Fortezza PC cards, which have since influenced the private communications market to be compatible with this technology. For instance, the Fortezza card comes in PCMCIA interface and is a very easy plug-n-play device to add on to mobile and wireless systems to provide encryption for wireless transmissions. Initially classified when it was first proposed, Skipjack was declassified in 1998, and it sparked numerous security analyses from security researchers worldwide because it provides insight into the state-of-the-art security design techniques used by a highly secretive government intelligence agency such as the NSA. In this paper, commemorating a decade since Skipjack's public revelation, we revisit the security of Skipjack, in particular its resistance to advanced differential-style distinguishers. In contrast to previous work that considered conventional and impossible differential distinguishers, we concentrate our attention on the more recent advanced differential-style and related-key distinguishers that were most likely not considered in the original design objectives of the NSA. In particular, we construct first-known related-key impossible differential, rectangle and related-key rectangle distinguishers of Skipjack. Our related-key attacks (i.e., related-key miss-in-the-middle and related-key rectangle attacks) are better than all the previous related-key attacks on Skipjack. Finally, we characterize the strength of Skipjack against all these attacks and motivate reasons why, influenced by the Skipjack structure, some attacks fare better. What is intriguing about Skipjack is its simple key schedule and a structure that is a cross between conventional Feistel design principles and the unconventional use of different round types. This work complements past results on the security analysis of Skipjack and is hoped to provide further insight into the security of an NSA-designed block cipher; the only one publicly known to date. [ABSTRACT FROM AUTHOR]

A declassified document confirms that the United States' 1943/4 Bombes continued to be used against the German's Enigma encryption device until at least 1955. [ABSTRACT FROM AUTHOR]