Sirvi Autor "Ekhall, Magnus" järgi

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Early Mechanical Cryptography and Binary Keying or The Possible Impact of the Damm Brothers on Leibniz’s Machina Deciphratoria
(Tartu University Library, 2026-06-22) Dahlke, Carola; Ekhall, Magnus; Desenclos, Camille; Pierrot, Cécile
Mechanical cipher machines employing binary keying elements became widespread in the first half of the twentieth century. This paper examines the origins of binary keying in mechanical cryptography, motivated by Gottfried Wilhelm Leibniz’s early work on binary arithmetic, his calculating machine (Machina Arithmetica), and his documented interest in cryptology. By analysing Leibniz’s surviving descriptions of a proposed cipher machine (Machina Deciphratoria), a reconstruction of this machine from 2012, and early cipher machines developed by Arvid Damm, we found no evidence that binary keying was intended in Leibniz’s cryptographic ideas. Instead, binary keying appeared as a distinctly twentieth-century development. The article highlights the possibility that reconstructions — when based on sparse sources — may unintentionally incorporate later design concepts into the reconstructed device, so that a historical device could be retroactively influenced by a modern idea.
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Playfair crib validation as a constraint satisfaction problem
(Tartu University Library, 2025) Ekhall, Magnus; Antal, Eugen; Marák, Pavol
This paper shows how a crib1 for a Playfair enciphered message can be seen as a constraint satisfaction problem. This problem can then be solved with standard constraint programming tools. The solution will tell whether the crib is possible, and if so, can list all possible Playfair keys that would result in the given crib.
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The TICOM DF-114 Cryptanalytic Device - A Theory of Operation and Computer Simulation
(Tartu University Library, 2024) Ekhall, Magnus; Waldispühl, Michelle; Megyesi, Beáta
The M-209 cipher machine was used extensively by the U.S.A. during WorldWar II. It is known that German cryptanalysts under certain circumstances were able to decipher M-209 enciphered messages using pen-and-paper techniques. A German wartime document found by the allies’ Target Intelligence Committee (TICOM) in 1947 describes a electromechanical machine that supposedly could be used as an aid when breaking M-209 enciphered messages. The document, designated DF-114 by TICOM, is quite technical but does not describe how the device would work. This paper suggests a theory of how the device could have been used, and by creating a computer simulation of the device described in DF-114 explores the viability of the theory.