International Conference on Historical Cryptology

Preface

Arno Wacker — Tue, 30 May 2023 00:00:00 +0200

We are very pleased to introduce the proceedings of the 6th International Conference on Historical Cryptology (HISTOCRYPT 2023), held at the Deutsches Museum in Munich, Germany from June 20–22, 2023.

Simulating Cryptologic History

Peter Krapp — Tue, 30 May 2023 00:00:00 +0200

Teaching the history of cryptology depends on access to extant devices, not just their documentation and interpretation. Yet the devices that show major steps in the history of cryptology are rare. Replicas, emulators, and simulations are pivotal for the history of cryptology.

The first volume of the Venetian ciphers written by Agostino Amadi

David Scheers — Tue, 30 May 2023 00:00:00 +0200

The secret manuscript of Agostino Amadi contains hundreds of cipher methods and examples. The total manuscript in ten volumes is translated from old Italian into English and published for the first time since 1588. Some examples from the first volume are presented here.

Encrypted Documents and Cipher Keys From the 18th and 19th Century in the Archives of Aristocratic Families in Slovakia

Eugen Antal, Pavol Marák, Pavol Zajac, Tünde Lengyelová, Diana Duchoňová — Tue, 30 May 2023 00:00:00 +0200

In this article, we present encrypted documents and cipher keys from the 18th and 19th century, related to central-European aristocratic families Amade-Üchtritz, Esterházy, and Pálffy-Daun. In the first part of the article, we present an overview and analysis of the available documents from the archives with examples. We provide a short historical overview of the people related to the analyzed documents to provide a context for the research. In the second part of the article, we focus on the digital processing of these historical manuscripts. We developed new tools based on machine learning that can automate the transcription of encrypted parts of the documents, which contain only digits as cipher text alphabet. Our digit detection and segmentation are based on YOLOv7. YOLOv7 provided good detection precision and was able to cope with problems like noisy paper background and areas where digits collided with the text from the reverse side of the paper.

The cipher of Emperor Rudolf II’s “Alchemical Hand Bell”

Richard Bean, Corinna Gannon, Sarah Lang — Tue, 30 May 2023 00:00:00 +0200

We examine a cipher found inscribed in the so-called “Alchemical Hand Bell” from the Kunstkammer of Emperor Rudolf II. We provide insight into the bell’s history, a correction for an existing published transcription, perform statistical analysis of the ciphertext, and look at possible encryption methods and plaintext languages. Given the analysis, we examine the possibilities of digraphic and polyphonic ciphers and give a brief overview of how these were used in the historical context.

Ottavian Medici and the decline of Venetian cryptography

Paolo Bonavoglia — Tue, 30 May 2023 00:00:00 +0200

The recent discovery, in the State Archives of Venice, of a 1621 final account from a committee of three noblemen charged to evaluate cipher services, sheds new light on the decline of cryptography in Venice in the subsequent centuries. The committee produced not only its evaluation, but also a new, interesting cipher, by the young Ottauian Medici. But, after Medici, stagnation and decline set in, until the final collapse of the Republic of Venice in 1797.

The Making of Fritz Menzer - A Secret Life

Carola Dahlke, Robert Jahn — Tue, 30 May 2023 00:00:00 +0200

A technical museum and a filmmaker join for a thoroughly researched documentary about Fritz Menzer, the widely unknown German inventor of cipher device 41. In seven episodes, they uncover Menzers secret life, and identify his central role for German cryptology.

A “Mirror for All Traitors”. Captured Ciphertexts from a Portuguese Spy in Dutch Brazil (1646)

Jörgen Dinnissen, Hugo Araújo — Tue, 30 May 2023 00:00:00 +0200

A deciphering report found in the National Archives at The Hague presents an intriguing story. A Portuguese spy inside the walls of Recife gathered information about the Dutch defences and wrote it in encrypted letters addressed to the Portuguese rebels that besieged the heart of the Dutch West India Company (WIC) administration in Brazil. The encrypted letters were delivered to the Dutch authorities, who summoned a Jewish cryptanalyst to read them. The report of Abraham de Pina contains a detailed description of the process he used to decipher these letters and presents the complete content of all four ciphertexts. In this paper, we will reconstruct the events of this case and analyze the design of the nomenclature cipher used by the Portuguese rebels. We also will present the flow of information of these intercepted letters within the WIC in Brazil and between them and their company superiors, the Gentlemen XIX, in the Netherlands.

A WW2 device for breaking the M-209 encryption machine

Magnus Ekhall, Klaus Schmeh — Tue, 30 May 2023 00:00:00 +0200

According to an eyewitness report by German engineer Reinold Weber published in 2004, a German cryptanalysis unit broke the U.S. cipher machine M-209 in the Second World War. For this purpose, the specialists involved built an electromechanical machine (“Weber machine”), which included binary logic and bore some resemblance with the Turing Bombe. In previously unpublished documents contained in the TICOM reports, information can be found about a cryptanalysis device that is probably identical with the Weber machine. Based on the said sources, this paper describes what is known about this deciphering technology.

Mysteries of P.C. Cadix and its evacuation in 1942/43

Marek Grajek — Tue, 30 May 2023 00:00:00 +0200

From 1940 to 1942 a group of Polish codebreakers, authors of the initial Enigma breakthrough, had been working at the P.C. Cadix, a secret codebreaking center situated in the unoccupied France. Their work in this period, and in particular the circumstances of their evacuation after the German/Italian occupation of Vichy France, are shrouded in mystery. This paper represents an attempt to put information known so far into a broader context, revealing in the process possible distortions and omissions in the accounts of the participants of the events.

The History of the Development and the Analysis of the Cipher Machine T-310/50 and the Procedure ARGON by the ZCO

Wolfgang Killmann — Tue, 30 May 2023 00:00:00 +0200

This paper describes important aspects of the 10 years of development and the 18 years of security analysis of the cipher machine T-310/50 and the procedure ARGON by the Central Cipher Authority of the GDR. The threat model of the analysis is pictured. Examples of the security analysis of the cipher algorithm, machine, procedure and key management are provided. The focus is on the analysis of the operating functions of the T-310/50 (operating analysis), including the analysis of operating errors, as well as the analysis of the instruction manual for the cipher procedure ARGON. The possibilities of obtaining information by an attacker from traffic reconnaissance in general and decryption attacks in particular are assessed.

Deciphering Secrets Throughout History: An Interdisciplinary Linguistics and Cryptology Course

Eunice Kim, Christian Millichap — Tue, 30 May 2023 00:00:00 +0200

This paper describes an interdisciplinary approach to teaching a linguistics and cryptology course. The authors, a Classics professor and a Mathematics professor, co-taught a three-week course, entitled “Deciphering Secrets Throughout History,” to undergraduate students of varying backgrounds in mathematics and the humanities. Students were taught to apply tools from linguistics, statistics, and cryptanalysis to examine ancient texts, languages, and ciphers. The course culminated in an extended analysis of the fifteenth-century Voynich Manuscript, where students proposed their own original analyses of the text.

Situating ciphers among alchemical techniques of secrecy

Sarah Lang — Tue, 30 May 2023 00:00:00 +0200

This paper offers a contextual framework for the historical analysis of alchemical ciphers. It argues that they differ from other ciphers due to their unique context: the alchemical tradition embodies a performative culture of secrecy, which employs a variety of techniques to achieve this performance. This paper contends that the distinction between ‘secret as content’ versus ‘secrecy as practice’ presents a useful framework for understanding alchemical rhetorics of secrecy and their relationship to alchemical cryptography. Additionally, it demonstrates how these principles can be applied in interpreting several examples.

Armand de Bourbon’s Poly-Homophonic Cipher – 1649

George Lasry — Tue, 30 May 2023 00:00:00 +0200

We deciphered two letters from 26 and 27 March 1649, from Armand de Bourbon, Prince de Conti, a leader of the Fronde. Probably addressed to the marquis Louis II de La Trémoille-Noirmoutier, they discuss recent developments in the Parliament of Paris and in French provinces. The cipher is polyhomophonic, a combination of a homophonic cipher, where each plaintext letter may be represented by several cipher symbols, and a polyphonic cipher, where a cipher symbol may represent several plaintext letters. To the best of our knowledge, this is the only documented example of such a cipher.

International Conference on the Voynich Manuscript 2022

Tue, 30 May 2023 00:00:00 +0200

The International Conference on the Voynich Manuscript, which took place 30 November and 1 December 2022, was the first peer-reviewed conference that was dedicated entirely to the Voynich MS. The only similar event took place ten years earlier at Villa Mondragone, Frascati, Italy, with invited presentations but without published proceedings (Schmeh, 2013). This paper summarises the event, its preparation and organisation, with a summary of the papers that were presented and potential avenues for further research.

Historical Language Models in Cryptanalysis: Case Studies on English and German

Tue, 30 May 2023 00:00:00 +0200

In this paper, we study the impact of language models (LM) on decipherment of historical homophonic substitution ciphers. In particular, we investigate if decipherment by using hill-climbing and simulated annealing can benefit from LMs generated from historical texts in general and century-specific texts in particular. We carry out experiments on homophonic substitution ciphers with English and German as plaintext languages. We take into account ciphertext length as well as n-gram size of the LMs. We compare the results on decipherment based on historical LMs with large LMs generated from modern texts. The results show that using historical LMs in decipherment of homophonic substitution ciphers leads to significantly better performance on ciphertext produced in the 17th century or earlier, and century-specific language models yield better results on longer and older ciphertexts.

What is the Code for the Code? Historical Cryptology Terminology

Tue, 30 May 2023 00:00:00 +0200

The cross-disciplinary nature of historical cryptology involves the challenge to find a terminology that is both consistent and accepted across the different disciplines and applicable in the single fields. In this paper, we propose a terminology based on concise principles developed by an interdisciplinary group of researchers. We present terms prominent in the study of historical cryptology, define them, and illustrate their usage. Our goal is to initiate and/or continue the discussion of how we use various terms for different types of historical encrypted sources, and their study. Our hope is that this paper will contribute to consistent and systematic usage of terms in the HistoCrypt community.

Encrypted epigraphy - the case of a mysterious inscription in the Neapolitan church of Santa Maria La Nova

Cosimo Palma — Tue, 30 May 2023 00:00:00 +0200

This paper contains all steps regarded as necessary and relevant towards the decryption of the epigraph placed in the “Turbolo Chapel” of the Neapolitan Church of Santa Maria La Nova. The inscription has been processed by means of Python- written procedures in combination with the decryption software AZdecrypt, thus displaying linguistic features converging unequivocally to the hypothesis that its clear-text be encrypted by monoalphabetic substitution from a natural language, possibly alongside with transposition and polyalphabetism. A preliminary analysis on characters n-grams and vocals-consonants combinations has not succeeded yet in individuating any clear-text language among all the analysed corpora.

Deciphering Charles Quint (A diplomatic letter from 1547)

Cécile Pierrot, Camille Desenclos, Pierrick Gaudry, Paul Zimmermann — Tue, 30 May 2023 00:00:00 +0200

An unknown and almost fully encrypted letter written in 1547 by Emperor Charles V to his ambassador at the French Court, Jean de Saint-Mauris, was identified in a public library, the Bibliothèque Stanislas (Nancy, France). As no decryption of this letter was previously published or even known, a team of cryptographers and historians gathered together to study the letter and its encryption system. First, multiple approaches and methods were tested in order to decipher the letter without any other specimen. Then, the letter has now been inserted within the whole correspondence between Charles and Saint-Mauris, and the key has been consolidated thanks to previous key reconstructions. Finally, the decryption effort enabled us to uncover the content of the letter and investigate more deeply both cryptanalysis challenges and encryption methods.

On the Combination of Cryptography and Steganography in 17th Century Germany

Eveline Szarka — Tue, 30 May 2023 00:00:00 +0200

Assessing and averting possible interception lies at the heart of cryptology. In handbooks printed in 17th century Germany, the authors suggested combining steganography and cryptography to increase information security. This article discusses several techniques for concealing ciphers and demonstrates that the authors of instructional literature had to consider complex interplaying factors when it came to combining cryptography and steganography. Overall, these examples show that the cryptological literature of the 17th century mirrors an increased discussion about the visibility of ciphers.

Scherbius and the Enigma. Political, Economic and Military Conditions

Claus Taaks — Tue, 30 May 2023 00:00:00 +0200

In 1917, the German War Ministry commissioned Arthur Scherbius to invent a cipher machine. The early history of the device was determined by political and economic disasters. The Enigma was taken up by dubious businessmen in 1920. In 1925 that ended in a catastrophe.

“We just did it!” – Female employees in Swedish sigint during the Second World War

Fredrik Wallin — Tue, 30 May 2023 00:00:00 +0200

When the Swedish sigint agency, FRA, was formed in 1942, the civilian personnel consisted of 67 percent women. This paper explores the roles and duties performed by women at the FRA during the wartime years and their working conditions.

Runic cryptography in early epigraphic period (200-700)

Sebastien Zimmermann — Tue, 30 May 2023 00:00:00 +0200

Runic script is an alphabetic system based on a non-alphabetical order row. The oldest row contained 24 letters but was reduced to 16 in Scandinavia around 800, and enlarged to 28 then 31 letters in England between 7th and 10th century (See Duwel, 2008). Runic script also adopted various original encryption systems during Viking and Middle Ages. Recent and very complete studies help us to understand the way they worked, both on social and technical levels. Nevertheless, the very first uses of cryptography are probably far much older and could have even occurred since runic script is first attested, that is in the end of 2nd century. It should be emphasized that it was based on a visual effect and riddles which goal was to make guess names rather than magical formulae. Indeed, the use of magical formulae is only attested lately, in the medieval times in Scandinavia and England inscriptions, and it is clearly related to Christian prayers and Kabbala (Bauer, 2020). This article aims to provide a chronology and a typology of possible cryptography techniques used with runic script in its earliest period.