A recursive solution for Turing’s H-M factor

Turing devised an electromechanical device, called a Bombe, to decipher German Enigma messages. His original design was considerably improved by the addition of Welchman’s diagonal board, allowing the use of much weaker menus and even menus without closures. Turing then made some extensive calculations to predict the performance of the improved Bombe. He provided a table, called the H-M factor, which allowed the expected number of stops to be predicted for menus containing a given number of letters and closures, but he gave no indication of how he constructed the table. This article is of technical interest and sheds some light on the H-M factor, including its variability with the tree-arrangement of the menu. It derives the H-M factor using a recursive technique for both the standard Bombe and the Jumbo Bombe, a later version incorporating the machine gun mechanism. These results may be of interest to those that code or run Bombe emulators.     

Breaking “Tirpitz”: Cryptanalysis of the Japanese-German joint naval cipher

This article gives the solutions of the only four messages known to still exist from the previously unbroken Japanese-German joint naval radio communications traffic in the system known as “Tirpitz,” which used the specially-designed model T Enigma machine. It also explains the methods used by the author to break the messages, and gives some background on the model T Enigma and its usages.     

Anecdotes

Many academic and almost all popular accounts present World War II cryptographic and cryptoanalytic activities as an interplay between Nazi Enigma cipher devices and Allied code breakers at Bletchley Park. To a lesser extent, academics have also documented the cryptoanalytic activities at the US Naval Communications Annex. However, a third center of Allied code breakers was located at the US Army's Arlington Hall Station, and its existence and activities are largely missing from the public record. Allied cryptanalysts began their attack on the Axis cipher systems, first mathematically and then later with machines. The code breakers used specialized machines such as the Bombe and Colossus, as well as modified and unmodified office equipment.     

NAVAL ENIGMA: M4 AND ITS ROTORS

The wiring of rotors in the naval version of Enigma is given (including that of beta and gamma) and events leading to the introduction of Triton, a cipher for Atlantic U-boats, are described. It is shown that an alpha rotor did not enter service, and that Triton became operational in October 1941.     

Mouse Selection Versus Voice Selection of Menu Items

Subjects completed a menu selection task using mouse and spoken language technologies for menu sizes that are powers of 2 from 2 to 256. It was found that mouse selection was faster than spoken language selection for menu sizes of 32 or less for most subjects. For small N, mouse selection was about three times faster. Spoken language selection was as fast or faster for menus of size 64 or larger. The trade-off size, approximately 64, was different for various subjects, but not greatly different. Data was gathered for words with one, two, and three syllables with the result that the trade-off size was the same for all three, but the error characteristics for spoken inputs were worse for shorter words, as would be expected.     

NAVAL ENIGMA: SEAHORSE AND OTHER KRIEGSMARINE CIPHER BLUNDERS

Describes major weaknesses in a naval Enigma cipher codenamed Seahorse, and how it and similar naval Enigma ciphers were solved by US Navy codebreakers during WWII.     

UMKEHRWALZE D: ENIGMA'S REWIRABLE REFLECTOR - PART III

Umkehrwalze D was a field-rewirable reflector for the German service Enigma machine, introduced primarily on German Air Force cipher networks late in the Second World War. This article discusses the history of the device and the various techniques and machines developed by the British and American signals intelligence agencies to deal with it.     

UMKEHRWALZE D: ENIGMA'S REWIRABLE REFLECTOR - PART II

Umkehrwalze D was a field-rewirable reflector for the German service Enigma machine, introduced primarily on German Air Force cipher networks late in the Second World War. The three parts of this article discuss the history of the device and the various techniques and machines developed by the British and American signals intelligence agencies to deal with it.     

Comparison of 3D and 2D menus for cell phones

Few prior studies have directly compared 3D and 2D menus for cell phones. Because the technology available for cell phone interfaces has changed in recent years, interface guidelines for cell phones need to be re-evaluated, especially with regard to the use of 3D interfaces. In the present study, we first compared performance of tasks for menus with different breadths using three 3D menus (revolving stage, 3D carousel, and collapsible cylindrical tree) shown on the small display screen of an iPhone® simulator. Performance was best with the revolving stage menu, and there was a nonsignificant tendency for it to be rated as preferred by the participants. Then, we compared the 3D revolving stage menu to a 2D overview menu, for tasks of different complexity and menus of different breadths, on an actual iPhone. The 3D menu was preferred by users at high breadth levels, and the 2D menu showed better performance than the 3D menu with low memory load. From the results, recommendations for the design of menus for small displays were developed.     

Genuine French WWII M-209 cryptograms

Abstract

In the French Army archives three cryptograms encrypted by the M-209 were found. They date from 1944 and come from the 1st French Army. Since the security rules in the military require them to be destroyed, it is extremely rare to have access to this type of document.

This article aims to show the use of the M-209 in the French Army. It will first briefly describe the operation of the M-209 encryption machine and describe the cryptographic means used by the French Army during the Second World War, including the M-209 provided by the Americans. The three cryptograms found in the archives will then be studied. The various components of these messages are described, starting with the key groups (which provide the message key) and continuing to the main abbreviations as well as some codenames. The plaintexts will then become understandable. This article ends with the reconstruction of the keys (internal and external) of the first two messages. This reconstruction could not be completed for the third message: it is given as a challenge to the readers of Cryptologia. This is also the opportunity to balance the security of the M-209 with that of the Enigma.     

FROM THE DEPTHS TO THE HEIGHTS: BOOK REVIEWS

The Enigma cipher machine had the confidence of German forces who depended upon its security. This misplaced confidence was due in part to the large key space the machine provided. This paper derives for the first time the exact number of theoretical cryptographic key settings and machine configurations for the Enigma cipher machine. It also calculates the number of practical key settings Allied cryptanalysts were faced with on a daily basis throughout World War II. Finally, it shows the relative contribution each component of the Enigma added to the overall strength of the machine.     

UMKEHRWALZE D: ENIGMA'S REWIRABLE REFLECTOR - PART I

Umkehrwalze D was a field-rewirable reflector for the German service Enigma machine, introduced primarily on German Air Force cipher networks late in the Second World War. The three parts of this article discuss the history of the device and the various techniques and machines developed by the wartime British and American signals intelligence agencies to deal with it.     

移动终端声音增强菜单交互研究*

为了提高移动交互的可用性,进行了用非语音声音来增强移动终端菜单交互的研究,首先设计了一个移动终端的声音增强菜单,然后通过与相应的视觉菜单的对比实验来研究其是否能提高可用性。结果显示,声音增强移动菜单具有更好的可用性,声音增强移动菜单可以显著减少任务完成时间、降低工作负荷和脑力负荷。这说明有效利用声音增强移动菜单交互技术可以提高移动终端菜单交互的可用性。     

Modern breaking of Enigma ciphertexts

“Breaking German Army Ciphers” is the title of a Cryptologia article from 2005, describing the lucky survival of several hundred authentic Enigma messages of World War II, and an account of a ciphertext-only cryptanalysis of a large number of these messages, leaving only a few (mostly short messages) unbroken. After reviewing the work done, and investigating the reasons for both lucky breaks and close misses, the modern ciphertext-only attack on Enigma messages is improved, especially on genuine ones with short lengths and/or many garbles. The difficulties of a proper measure for the candidate’s closeness to a plaintext are clarified. The influence on the decryption process of an empty plugboard and one with only a few correct plugs is examined. The method is extended by a partial exhaustion of the plugboard combined with an optimized hillclimbing strategy. The newly designed software succeeds in breaking formerly unbroken messages.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).     

AuthorWare中动态快捷菜单的设计与实现

Authorware是课件开发的利器,虽然它支持一级菜单交互,但是不支持子菜单交互,更不支持右键快捷菜单设计。而使用tMsControls.u32插件结合系统函数能在Authorware中实现动态快捷菜单设计。文中详细介绍了tMsControls.u32插件的函数功能和动态快捷菜单的实现原理,通过实例介绍了如何通过动态快捷菜单控制可视媒体的新方案。     

ALAN TURING'S VISIT TO DAYTON

Recently declassified documents from the “Crane Collection” at the National Archives (USA) reveal much of the purpose of Alan Turing's visit to the United States during the Winter of 1942–1943. The “Bombe Correspondence” file contains Turing's “Visit To National Cash Register Corporation of Dayton, Ohio” and additional material which places this report and his earlier “Treatise on the Enigma” in the context of his role as consultant to the U. S. Navy Cryptanalytic Section (Op-20-G) on the design of the Navy Bombe and other related matters. The documents in this collection reveal a productive and decisive relationship between Turing and Op-20-G dating from the visit of the Sinkov mission to Bletchley Park in February 1941.     

THE SWISS NEMA CIPHER MACHINE

The Enigma is probably the most well known wired wheel cipher machine. The NEMA is a cipher machine developed during World War II by the Swiss Army. It is designed on the same principle as the Enigma but with particular emphasis on overcoming some of its weak features. It was declassified by the Swiss Authorities in 1992. This paper describes its mechanism and the way in which it operates, so that it may be more widely known to cryptology researchers.     

Spanish Enigma: A History of the Enigma in Spain

Abstract

The presentation of a brief study of the use of Enigma Machines in Spain, during the Spanish Civil War (1936–1939) and later, until their final replacement.     

18TH CENTURY SHORTHAND EXPERT NEEDED (RE-RUN)

Abstract

Fialka M-125 (sometimes called the “Russian Enigma”) is an electro-mechanical rotor cipher machine used during the Cold War. The designers of this cipher eliminated the known weaknesses of Enigma. In this article, the authors summarize the main principle of the Fialka algorithm from public sources. Moreover, they introduce a mathematical model of the Fialka cipher, and they analyse the effect of blocking pin settings on the cipher's period.