Proceedings of the 7th International Conference on Historical Cryptology (HistoCrypt 2024)

Selle kollektsiooni püsiv URIhttps://hdl.handle.net/10062/98421

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Overlooked, forgotten, misunderstood: the "other" SIGINT in World War II
(Tartu University Library, 2024) Hatch, David; Waldispühl, Michelle; Megyesi, Beáta
Fascination with ULTRA, the extraordinary World War II cryptologic intelligence, by historians and the public alike has eclipsed knowledge of and study of a second important cryptologic intelligence source. Whereas ULTRA provided senior Allied leaders with deep insight into enemy strategic thinking and plans, tactical cryptologic intelligence often gave combat commanders the vital information needed to win actual battles. Tactical cryptologic intelligence is less known and studied partly because it is in the shadow of ULTRA. In addition, fewer sources about the practice of tactical cryptologic intelligence have survived, and those readily available are fragmented and anecdotal. Tactical cryptologic intelligence merits further research and analysis if we are to have a fuller understanding of cryptology in practice and intelligence in the world war.
An early French digit cipher: deciphering a letter from the King of France to the Duke of Nevers (1592)
(Tartu University Library, 2024) Desenclos, Camille; Lasry, George; Waldispühl, Michelle; Megyesi, Beáta
We deciphered a single letter written in 1592 by Henry IV, King of France, to Louis de Gonzague, Duke of Nevers, held in the Bibliothèque Nationale de France (BnF). The ciphertext mostly consists of contiguous digits, and demonstrates an early use of digit ciphers in 16th-century France. In this letter, Henri IV exposes some parts of his current military strategy against the Catholic League. After deciphering the letter, we were able to locate the original cipher table in another BnF manuscript, illustrating how codebreaking may assist historical research both to reconstruct the content of encrypted letters and to identify anonymous cipher tables.
Fake or real? A mysterious metal book on the market
(Tartu University Library, 2024) Király, Levente Zoltán; Láng, Benedek; Tokai, Gábor; Waldispühl, Michelle; Megyesi, Beáta
A newly emerged gilded folio metal book containing illustrations and unreadable character strings raises the question of authenticity. The article describes the object and examines on what grounds can be claimed with relative confidence that such a book is a forgery. The examination includes a structural analysis of the symbol sets and a comparison with similar, analogous metal books.
A Typology for Cipher Key Instructions in Early Modern Times
(Tartu University Library, 2024) Megyesi, Beáta; Láng, Benedek; Kopal, Nils; Mikhalev, Vasily; Tudor, Crina; Waldispühl, Michelle; Waldispühl, Michelle; Megyesi, Beáta
We present an empirical study on instructions found in historical cipher keys dating back to early modern times in Europe. The study reveals that instructions in historical cipher keys are prevalent, covering a wide range of themes related to the practical application of ciphers. These include general information about the structure or usage of the cipher key, as well as specific instructions on their application. Being a hitherto neglected genre, these texts provide insight into the practice of cryptographic operations.
Musician Cryptologists: The Band of the USS California at Pearl Harbor and Beyond
(Tartu University Library, 2024) Prescott, Kyle; Waldispühl, Michelle; Megyesi, Beáta
Working from the basement of US Pacific Fleet Headquarters in Pearl Harbor from 1941, a small team of navy cryptanalysts and linguists known as the Combat Intelligence Unit (CIU) provided the US Pacific Fleet Command with timely details of the capabilities and intentions of the Japanese Imperial Navy (IJN) in the Pacific. A substantial portion of the CIU was comprised of 20 enlisted musicians of US Navy Unit Band 16, the band of the USS California (BB-44), who survived the sinking of their ship in the attack of December 7, 1941. The musicians were recruited to Combat Intelligence, retrained to perform tasks related to the deciphering of Japanese Naval Code JN-25b, and contributed to that unit’s celebrated intelligence successes of 1942. As the war waged on, several musicians from Band 16 transferred to the Naval Communications Complex at Nebraska Avenue in Washington DC, and three eventually joined the National Security Agency (NSA) and served through the height of the Cold War.
Lost in Translation: Missing Background, Contextual Blindspots, and Editing Mishaps in Translated Intelligence Content
(Tartu University Library, 2024) Jaskoski, Stephen; Waldispühl, Michelle; Megyesi, Beáta
This article examines the content as rendered by a small sample of intelligence reports issued by the UK Government Code and Cypher School (GC&CS) at Bletchley Park that address the initial indications in Italian communications of Italian regime change after Mussolini and considers how higher meaning in the texts may not have been fully appreciated in the context when they were written. The episode offers lessons in grasping context and significance in translated material.
Cryptology and redaction – a strange symbiosis
(Tartu University Library, 2024) Turing, Dermot; Waldispühl, Michelle; Megyesi, Beáta
This paper explores the relationship between cryptology and redaction. Redaction can be a frustration to historical cryptology research. Examples of redactions of historical papers relevant to cryptology are presented. It is concluded that the practice of redaction is often ineffective and the policy rationale behind redactions difficult to understand.
A new perspective on Dutch WWI codebreaking with its international ramifications
(Tartu University Library, 2024) Jacobs, Bart; van Kampen, Florentijn; Waldispühl, Michelle; Megyesi, Beáta
During the First World War, the Netherlands maintained a stance of carefully guarded neutrality. International tele communications in the form of telephone and telegraph were closely monitored and censored by so-called censorbureaus. In 2019 new files were declassified and released to the Dutch National Archive about the secensorship bureaus at Amsterdam and Rotterdam, covering 1914 to 1918. They provide detailed insight in the day-to-day business, the codebreaking efforts and specific cryptanalytic results. The material provides a completely new perspective on the genesis of modern Dutch codebreaking. This article gives a first survey of the development of these interception bureaus. It analyses their pioneering codebreaking activities and presents historic material on German diplomatic ciphers. Also, it provides new insight into the mysterious sale in 1919 of German codebooks from the Netherlands to the United States, as reported earlier in the literature.
Decipherment of an Encrypted Letter from 1724 Found in UCL Special Collections’ Brougham Archive
(Tartu University Library, 2024) Kopal, Nils; Makin, Katy; Waldispühl, Michelle; Megyesi, Beáta
This paper shows the decipherment of a 1724 encrypted letter, discovered recently in the Brougham Archive at University College London (UCL) Special Collections. The letter’s content hints at political intrigue and possibly relates to the Jacobite movement during George I’s reign in Great Britain. However, as all individuals mentioned in the letter are referred to bycode names, except for Madame de Prie, their true identities remain unknown to the authors. Therefore, any connection to the Jacobites remains speculative. The paper covers the cipher’s security, historical context, and unresolved inquiries surrounding the letter.
Cryptanalysis of Hagelin M-209 Cipher Machine with Artificial Neural Networks: A Known-Plaintext Attack
(Tartu University Library, 2024) Mikhalev, Vasily; Kopal, Nils; Esslinger, Bernhard; Lampesberger, Harald; Hermann, Eckehard; Waldispühl, Michelle; Megyesi, Beáta
This paper introduces a machine learning (ML) approach for cryptanalysis of the ciphermachine Hagelin M-2091. For recovering the part of the secret key, represented by the wheel pins, we use Artificial Neural Networks (ANN) which take as input the pseudo-random displacement values generated by the internal mechanism of the machine. The displacement values can be easily obtained when ciphertext and plaintext are known. In particular, we are using several distinct ANNs, each recovering exactly one pin. Thus, to recover all the 131 pins, we utilize 131 model seach solving a binary classification problem. By experimenting with various ANN architectures and ciphertext lengths, ranging from 52 to 200 characters, we identified an ANN architecture that outperforms others in accuracy. This model, inspired by the architecture by Gohr used for attacking modern ciphers, achieved the following accuracies in recovering the pins of the first wheel of the machine: approximately 71% for 52-characters sequences, 88% for 104-characters, 96% for 200-characters. The first wheel has the largest size and hence represents the most complicated case. For the other wheels, these accuracies are slightly higher. To the best of our knowledge, this is the first time when ANNs are used in a key-recovery attack against such machines.
The enigma of Lorenzo Ventura’s cipher
(Tartu University Library, 2024) Bonavoglia, Paolo; Waldispühl, Michelle; Megyesi, Beáta
The aim of this research was to find the algorithm used in the ciphers mentioned by Blaise de Vigenère in his treatise, where he states that in 1569, while in Venice, he learned about a steganographic cipher by a certain Lorenzo Ventura, similar to Tritemio’s Ave Maria. It had been used by the bailo in Constantinople after Sultan Selim II prohibited him from writing his dispatches in cipher. Now that a collection of letters, notes, and handwriting examples belonging to Ventura has been found in the State Archives of Venice, initial findings emerge that confirm, at least in part, Vigenère’s claims.
How the MachinesWere Assisted by Women
(Tartu University Library, 2024) Fricker, Elizabeth S.D.; Waldispühl, Michelle; Megyesi, Beáta
The following paper analyzes nature of skill in the cryptographic work performed by female employees of the World War II British cryptography program at Bletchley Park. Using anecdotes from women who worked to decrypt the Lorenz cipher, I show the hidden skills which were integral to their work and to the war effort. This paper aims to reconstruct their experiences and deepen our understanding of what it took to operate decryption machines, especially focusing on the Colossus computer.
Artificial neural network for hoax cryptogram identification
(Tartu University Library, 2024) Foxon, Floe; Waldispühl, Michelle; Megyesi, Beáta
Numerous putative cryptograms remain unsolved. Some, including the Dorabella cryptogram, have been suggestedas hoaxes, i.e., some sort of gibberish with no meaningful underlying plaintext.The statistical properties of a putative cryptogram may be modelled to determine whether the cryptogram groups moreclosely with real or with randomly generated plaintext. Ten thousand plaintexts from an English-language corpus, and ten thousand (pseudo-)randomly generated English-alphabet gibberish texts were studied through their statistical properties, including the alphabet length; the frequency, separation, and entropy of n-grams; the index of coincidence; Zipf’slaw, and mean associated contact counts. An artificial neural network (deep learning) model was fitted to these data, with a cross-validated mean accuracy of 99.8% (standard deviation: 0.1%). This model correctly predicted that arbitrary, out-of-sample simple substitution ciphers represented meaningful English plaintext (as opposed to gibberish) with probabilities close to 1; correctly predicted that arbitrary, out-of-sample gibberish texts were gibberish (as opposed to simple substitution ciphers) with probabilities close to 1; and assigned a probability of meaningful English plaintext of 0.9996 to the Dorabella cryptogram.
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.
Deciphering Historical Syllabic Ciphers
(Tartu University Library, 2024) Lasry, George; Waldispühl, Michelle; Megyesi, Beáta
Historical ciphers with syllabic elements are significantly more challenging for cryptanalysis than regular homophonic ciphers. We present here a novel computerized technique which recovers significant parts of the keys, allowing for the remaining parts to be manually completed. We solved several previously undeciphered French, Spanish, and Italian syllabic ciphers, and we also evaluated the performance of this method against a series of additional historical syllabic ciphers.
Post-quantum trails: an educational board game about post-quantum cryptography
(Tartu University Library, 2024) Vakarjuk, Jelizaveta; Snetkov, Nikita; Waldispühl, Michelle; Megyesi, Beáta
Post-quantum cryptography has gained more and more attention with the recent developments in quantum technology. There are already standard drafts for the novel post-quantum crypto systems and organisations are starting the process of migration to post-quantum cryptography. However, the migration process has many challenges that need to be taken into account. Moreover, the algorithms themselves have become more complicated, making it more difficult to educate people about post-quantum cryptography. We propose to use gamification to make it easier to explain the main challenges and obstacles as well as the main steps of the migration process to the non-cryptographic community. We propose a board game that is built using the gamification taxonomy of Toda et al. to ensure a smooth learning process.
What Encryption Errors Can Reveal: Cross-Cipher Errors in Mary Queen of Scots’ Letters
(Tartu University Library, 2024) Biermann, Norbert; Tomokiyo, Satoshi; Lasry, George; Waldispühl, Michelle; Megyesi, Beáta
In the recently deciphered letters from Mary Queen of Scots, a large number of systematic encryption errors were found and attributed to confusion as a result of concurrently using at least one other cipher key to communicate with a different recipient. In this paper, we further analyze such cross-cipher errors in those letters and identify additional cipher keys involved. This analysis also reveals valuable insights on the secret communications of Mary, Queen of Scots. We employ several techniques including statistical analysis, which may be applied to the analysis of encryption errors in other collections of historical enciphered documents.
The Use of Volvelles in Two Early Modern Cryptography Manuals
(Tartu University Library, 2024) Bayerl, Corinne; Waldispühl, Michelle; Megyesi, Beáta
This paper examines the form and function of volvelles (rotating paper discs) used to represent cipher systems in Giambattista della Porta’s De furtivis literarum notis (1563) and in the French translation of Trithemius’Polygraphia by Gabriel de Collange (1518, transl. 1561). I analyze the use of volvelles in cryptography handbooks within the larger context of their overall function in the Early Modern period, and I identify the factors that may account for an increasing use of volvelles in succeeding editions of della Porta’s and Trithemius’ works in the second half of the 16th century. Collange’s expanded version of Trithemius’ manual and della Porta’s numerous amended editions of his own handbook indicate that changes in the material representation of cipher systems correlate with an increased level of public knowledge about encryption methods.
Sources of Alchemical Cryptography
(Tartu University Library, 2024) Lang, Sarah; Zotov, Sergei; Piorko, Megan; Waldispühl, Michelle; Megyesi, Beáta
This paper presents an initial overview of cryptographic sources relating to alchemy, an area that remains largely unexplored. Alchemists and chymists frequently encrypted short passages relating to recipes and experiments, obscured content using exotic foreign languages or custom shorthand, and created unique symbol codes. A survey of manuscripts reveals the diversity of sources in over 100 instances of ciphering in alchemical contexts, where ciphers were only one of several methods traditionally used to maintain secrecy. It serves as a starting point for further research, demonstrating the wealth of archival material related to alchemical cryptography –a goldmine yet untapped.
Exploring the Alignment of Transcriptions to Images of Encrypted Manuscripts
(Tartu University Library, 2024) García, Goio; Torras, Pau; Fornés, Alicia; Megyesi, Beáta; Waldispühl, Michelle; Megyesi, Beáta
The automatic transcription of encrypted manuscripts is a challenge due to the different handwriting styles and the often invented symbol alphabets. Many transcription methods require annotated sources, including symbol locations. However, most existing transcriptions are provided at line or page level, making it necessary to find the bounding boxes of the transcribed symbols in the image, a process referred to as alignment. So, in this work, we develop several alignment methods, and discuss their performance on encrypted documents with various symbol sets.

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