Proceedings of the 9th International Conference on Historical Cryptology (HistoCrypt 2026)

Selle kollektsiooni püsiv URIhttps://hdl.handle.net/10062/121789

Sirvi

Nüüd näidatakse 1 - 20 28

listelement.badge.access-status Avatud juurdepääs ,
Proceedings of the 9th International Conference on Historical Cryptology
(Tartu University Library, 2026-06-22) Desenclos, Camille; Pierrot, Cécile
listelement.badge.access-status Avatud juurdepääs ,
A Medieval Czech Penitential Prayer Behind the Cryptographic Enigma of Santa Maria La Nova?
(Tartu University Library, 2026-06-22) Palma, Cosimo; Helm, Louie; Desenclos, Camille; Pierrot, Cécile
This paper presents renewed attack on the encrypted inscription housed in the Turbolo Chapel of the Neapolitan Church of Santa Maria La Nova. Following the cryptanalytic hypothesis of monoalphabetic substitution and the multilingual leads explored in related works, the present contribution investigates Old Czech, a candidate not yet systematically tested against the cipher. Through a combination of n-gram-driven automated decryption via AZdecrypt and LLM-assisted segmentation of the resulting scriptio continua, a candidate reading has been obtained, pointing to a medieval Czech penitential prayer. Although a definitive solution cannot be provided without the support of philologists and cryptologists versed in Czech and related languages, the convergence of statistical, lexicographic and thematic evidence constitutes to date the strongest cue for this long-standing historical puzzle.
listelement.badge.access-status Avatud juurdepääs ,
Cryptographic Practices within Jacobite Diplomatic Networks (1715–1745): A Typology of Ciphers and Keys in Wartime
(Tartu University Library, 2026-06-22) Rocher, Camille; Desenclos, Camille; Pierrot, Cécile
This paper examines cryptographic practices within Jacobite diplomatic networks between 1715 and 1745 through the systematic analysis of a corpus of 57 cipher keys among the 318 ones preserved in the Stuart Papers. While Jacobite correspondence has been studied from political perspectives, the cipher keys themselves have rarely been considered as historical objects deserving systematic analysis. Focusing on periods of intense military and diplomatic activity, this study investigates the structure, typology, and circulation of cipher keys used by James Francis Edward Stuart and his agents across Europe. This article proposes a typology based on the combination of cryptographic features observed in the corpus and hybrid systems. A frequency-based analysis highlights recurrent patterns in key design and reveals a strong preference for hybrid systems combining jargon with monoalphabetic or homophonic substitution. The results show no clear correlation between the complexity of a cipher key and the status of the correspondents involved, suggesting that pragmatic constraints, such as usability, availability, and key reuse, played a decisive role in cryptographic choices. By foregrounding cipher keys as artefacts of communication, this study contributes to a better understanding of early modern cryptographic practices and sheds new light on the operational dynamics of Jacobite diplomatic networks during wartime.
listelement.badge.access-status Avatud juurdepääs ,
Establishing a Document Layout Analysis Baseline for Historical Cipher Keys
(Tartu University Library, 2026-06-22) Heil, Raphaela; Fornés, Alicia; Láng, Benedek; Megyesi, Beáta; Desenclos, Camille; Pierrot, Cécile
Historical cipher keys encode mappings between plaintext elements and cipher symbols and are characterized by complex, heterogeneous handwritten layouts. This paper establishes a baseline for document layout analysis (DLA) of historical cipher keys using a newly annotated dataset of 350 images from European archives dating from ca. 1300 to 1850 CE. We evaluate four YOLO-based architectures under three conditions: training from scratch, cross-domain transfer from models pre-trained on DocLayNet and CATMuS in a class-agnostic setting, and fine-tuning of these pre-trained models on cipher key data. Results show that training from scratch is limited by data scarcity and unstable convergence, while direct transfer across DLA domains performs poorly. In contrast, fine-tuning consistently improves performance across all architectures, demonstrating the feasibility of adapting existing DLA models to cipher keys and supporting downstream tasks such as key extraction and comparative cryptographic analysis.
listelement.badge.access-status Avatud juurdepääs ,
The BACK IN TIME Project: A User-Centred Platform for Encrypted Historical Documents
(Tartu University Library, 2026-06-22) Pierrot, Cécile; Desenclos, Camille; Mera, Michaël; Kiessling, Benjamin; Damoiseau-Malraux, Gaspard; Aguili, Hassen; Clérice, Thibault; Desenclos, Camille; Pierrot, Cécile
Since the Late Middle Ages, sensitive correspondence (political, diplomatic, military, etc.) has frequently been encrypted. Thousands of these documents now lie in archives and libraries, yet they remain largely beyond the reach of humanities researchers. The sheer volume and complexity of these materials render both manual cryptanalysis and manual analysis impractical, if not impossible. Although recent advances in historical cryptanalysis and artificial intelligence have enabledpartial automation, existing tools remain ill-suited to the needs and practices of humanities researchers. The BACK IN TIME project was established in late 2024 to address these challenges. It seeks an alternative approach to automation that places the end user – namely, the humanities researcher – at the centre of the system’s design. In this paper, we articulate our vision for a user-centred assistive platform intended to bridge the current gap: we highlight how the guiding principles identified by the project team can be used to combine computer vision, cryptanalysis, and historical expertise into a user-centred design that makes historical cryptanalysis both accessible and compatible with established scholarly practices. Initial implementations will focus on Western European scripts and languages, as well as on manually encrypted documents (up to the early 20th century), reflecting the team’s expertise and easier access to these documents.
listelement.badge.access-status Avatud juurdepääs ,
Unsupervised Feature Learning via Convolutional Autoencoders for Cross-Manuscript Comparison in Historical Cryptanalysis
(Tartu University Library, 2026-06-22) Reinares Guerreros, Alejandra; de Gregorio, Giuseppe; Fornés, Alicia; Desenclos, Camille; Pierrot, Cécile
The study of historical enciphered manuscripts is fundamental to understanding our cultural heritage, yet a vast corpus of these archives remains inaccessible due to the complexity of ancient cryptographic systems. Traditional analysis relies heavily on manual expertise, a process that is labor-intensive and difficult to scale across the immense volume of unstudied documents. This paper proposes a novel, fully unsupervised framework for the automated comparative analysis of images of historical ciphers. Our approach leverages Convolutional Autoencoders (CAE) to learn intrinsic morphological features directly from manuscript images, bypassing the need for labeled datasets or prior knowledge of the cipher keys. By projecting symbols into a high-dimensional latent space, the system generates a “similarity fingerprint” for each manuscript, enabling a quantitative comparison of diverse documents. Experimental results demonstrate that this method effectively identifies relationships between ciphers, grouping them by cryptographic tradition. This framework provides historians with a powerful computational tool to detect shared lineages and map the evolution of secret communication across history.
listelement.badge.access-status Avatud juurdepääs ,
Encrypted official telegrams of the Vichy government
(Tartu University Library, 2026-06-22) Falut, André; Desenclos, Camille; Pierrot, Cécile
After the installation of Pétain’s government in Vichy, telegrams sent to its administration were received by a central telegraph station, which retained copies of the messages. A large proportion of the surviving messages, now kept at the French National Archives, is encrypted. This paper provides initial observations on these messages and their context, focusing on the years preceding the full occupation of mainland France
listelement.badge.access-status Avatud juurdepääs ,
Only Gentlemen Read Each Other’s Mail: Over 50 Years of Sittler Codebooks in the Dutch Diplomatic Service
(Tartu University Library, 2026-06-22) Boer, Jip; Desenclos, Camille; Pierrot, Cécile
The Dutch diplomatic service’s prolonged reliance on commercially available Sittler codebooks, despite repeated indications the books had been compromised, presents an interesting case study spanning the late nineteenth century to the early 1930s. With the use of the Sittler code as its focal point, this article explores how cryptographic practices were shaped as much by social norms, administrative capacities and financial constraints as by awareness of strategic security risks. Drawing primarily on archival material from the Dutch Ministry of Foreign Affairs, it demonstrates that continued use of the Sittler code reflected neither ignorance nor technological backwardness. Instead, it exposes a class-based, “gentlemanly”, conception of secrecy in which codes fulfilled a primary function of shielding information from subordinate staff and telegraph personnel, rather than from senior officials of foreign governments. Only under the external pressures of the First World War did concerns of foreign cryptanalytic threats lead to incremental security measures.
listelement.badge.access-status Avatud juurdepääs ,
Learning to Decipher from Pixels—A Case Study of Copiale
(Tartu University Library, 2026-06-22) Kang, Lei; Gregorio, Giuseppe De; Heil, Raphaela; Fornés, Alicia; Megyesi, Beáta; Desenclos, Camille; Pierrot, Cécile
Historical encrypted manuscripts require both paleographic interpretation of cipher symbols and cryptanalytic recovery of plaintext. Most existing computational workflows rely on a transcription-first paradigm, in which handwritten symbols are transcribed prior to decipherment. This intermediate step is labor-intensive, error-prone, and not always aligned with the goal of direct plaintext recovery. We propose an end-to-end, transcription-free approach that directly maps handwritten cipher images to plaintext. Using the Copiale cipher as a case study, we introduce the first text-line-level dataset pairing cipher images with German plaintext. We show that pretraining on generic handwriting data followed by cipher-specific fine-tuning substantially improves decipherment accuracy. Our results demonstrate that transcription-free image-to- plaintext decipherment is both feasible and effective for historical substitution ciphers, offering a simplified and scalable alternative to traditional pipelines.
listelement.badge.access-status Avatud juurdepääs ,
Joint Transcription and Decryption of Images of Encrypted Handwritten Documents: A Comparison with the Traditional Pipeline
(Tartu University Library, 2026-06-22) Megyesi, Beáta; Oliveros-Blanco, Marino; Fornés, Alicia; Kang, Lei; Desenclos, Camille; Pierrot, Cécile
Historical encrypted manuscripts present a challenging problem at the intersection of cryptology, linguistics, paleography, and computer vision. Current automatic decipherment approaches usually rely on a two-stage pipeline: transcription of cipher symbols from manuscript images, followed by decryption into plaintext. However, this design is sensitive to transcription errors, which propagate to the final output. We present Direct Image Decryption, an end-to-end approach that directly maps encrypted manuscript images to plaintext, bypassing the intermediate transcription stage. Using the Copiale cipher as a case study, we build a synthetic data generation pipeline to create large-scale cipher-like training data and compare the traditional pipeline with the proposed joint architecture. Results show that joint image-to-plaintext modeling is a promising alternative to traditional transcription-based pipelines.
listelement.badge.access-status Avatud juurdepääs ,
Exploring the Automatic Alphabet Identification of Images of Handwritten Ciphers
(Tartu University Library, 2026-06-22) Megyesi, Beáta; Reinares, Alejandra; Fornés, Alicia; Gregorio, Giuseppe de; Desenclos, Camille; Pierrot, Cécile
Historical encrypted manuscripts often use invented or heterogeneous alphabets, making alphabet identification a necessary but traditionally manual first step prior to transcription and decryption. This work explores the use of unsupervised computer vision methods to automate this task without requiring labeled data. We propose a pipeline that segments characters from cipher manuscripts, groups them into clusters of visually similar symbols using unsupervised methods, and compares those clusters against a reference database of known alphabet symbols to identify the most likely underlying writing system. Experiments show that the method can correctly identify the alphabet when a handwritten alphabet is available, but performance degrades when handwritten symbols are compared against printed alphabets, with handwriting style dominating shape similarity. These results highlight the importance of realistic handwritten reference alphabets.
listelement.badge.access-status Avatud juurdepääs ,
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.
listelement.badge.access-status Avatud juurdepääs ,
The Secret Writing of Michele Zoppello: An Introduction
(Tartu University Library, 2026-06-22) Vito, Marco; Desenclos, Camille; Pierrot, Cécile
Michele Zoppello is an insufficiently studied figure within the late medieval cryptographic landscape. Although his biography remains largely uncertain, it is enriched by the existence of a treatise on cryptography, which provides valuable insights into a rapidly evolving intellectual milieu. This paper takes a case study from his treatise, Litterarum Simulationis Liber, to examine the cipher system he devised, with particular attention to its strengths and limitations, thereby clarifying its role in the history of cryptography and its implications in the period. This study provides a basis for future research and further analysis of both Zoppello’s figure and his treatise, representing an initial step toward introducing this subject into scholarly debate on the history of cryptography.
listelement.badge.access-status Avatud juurdepääs ,
Solving Historical Ciphers with AI: Analysis of GPT’s Capability in Processing and Deciphering Cryptographic Postcards
(Tartu University Library, 2026-06-22) Antal, Eugen; Pavuk, Tomáš; Zajac, Pavol; Desenclos, Camille; Pierrot, Cécile
In this case study, we focus on the capabilities of ChatGPT for assisting in the research of historical encrypted documents. Our study is based on the dataset of historical encrypted postcards, typically with simple (substitution) ciphers. We split the task into two parts: transcription and interpretation of the postcard image, and then decipherment of the transcribed text. We summarize the current capabilities of (multimodal) AI tools in general, and specifically of GPT-5.2 / GPT-4o that were used as AI tools in our analysis. Following our cryptanalytic pipeline, we show specifically how the AI tool was capable of solving selected typical exemplars from our dataset. We show that GPT-5.2 is already capable of solving most of the required tasks with acceptable quality, and can be useful even for researchers not specifically trained in prompt engineering or artificial intelligence usage.
listelement.badge.access-status Avatud juurdepääs ,
The Codebook of Willem Six van Oterleek: Dutch Diplomatic Intelligence from Saint Petersburg between 1806-1810
(Tartu University Library, 2026-06-22) van Kampen, Florentijn; Desenclos, Camille; Pierrot, Cécile
Between 1806 and 1810, Willem Six van Oterleek served as diplomatic representative of the Netherlands in Saint Petersburg, Russia. During these years, van Oterleek kept his Minister of Foreign Affairs informed as fully as possible about political developments, information he received from other diplomats and the couleur locale from his posting in Saint Petersburg. This sensitive communication was to be kept secret and was therefore sent in code. These coded messages and the accompanying codebook that was used to protect them survived in the Dutch National Archives. This article will explore this codebook, analyse code usage and decode the secret messages to present a unique peek behind the curtain of the diplomatic developments and intrigues of those days.
listelement.badge.access-status Avatud juurdepääs ,
“Was Early Modern Shorthand Cipher? Some Examples from Late Stuart England”
(Tartu University Library, 2026-06-22) McKenzie, Andrea; Desenclos, Camille; Pierrot, Cécile
This paper addresses the question of whether early modern shorthand, a scribal technology first widely used in seventeenth-century England, qualifies as “cipher”. In addition to the famous shorthand diary of Samuel Pepys (1633-1703), it will examine the previously undeciphered shorthand of several other late Stuart figures, with a particular focus on the lawyer and Member of Parliament Sir George Treby (c.1643-1700). Just as the authors of stenographic manuals touted shorthand as “secret writing”, writers like Pepys and Treby clearly employed strategies to make their shorthand (or parts of it) difficult either to decipher or detect. Early modern shorthand can pose significant challenges for scholars, especially in cases where the system used is unknown; as with contemporary ciphertext, cracking these sources often requires painstaking contextual analysis currently beyond the powers of artificial intelligence.
listelement.badge.access-status Avatud juurdepääs ,
Enigma-Fusion: Connecting Digital Twin and 3D-Printed Reconstruction
(Tartu University Library, 2026-06-22) Strobel, Joanna; Schmutterer, Felix; Lewis, Noah; Desenclos, Camille; Pierrot, Cécile
This paper presents the design and realization of a fully functional, 3D-printed replica of the Enigma cipher machine, coupled with an interactive digital twin via a hardware–software interface. Beyond the acquisition of practical and transferable skills, the project enabled student participants to develop a thorough understanding of the machine’s mechanical operation, encryption principles, and historical relevance. The combined physical and digital system supports an illustrative and transparent demonstration of the Enigma’s internal processes, making its cryptographic functionality accessible and comprehensible to a broad audience.
listelement.badge.access-status Avatud juurdepääs ,
Location Matters: Accelerating Historical Cipher Transcription with Detection-Based Models
(Tartu University Library, 2026-06-22) Lasry, George; Desenclos, Camille; Pierrot, Cécile
Transcribing historical ciphers is the first step toward decryption and analysis. Machine learning models proposed for this task often neither consume nor produce symbol locations. Such location-discarding approaches do not integrate naturally with transcription and analysis tools that rely on a visual feedback loop linking image regions to transcribed symbols. We argue for location-aware, detection-based deep learning models that preserve location information in both supervision and output, supporting an end-to-end visual workflow with tools such as CTTS (CrypTool Transcription and Solver). To this end, we present two detection-based models with distinct architectures, evaluate them quantitatively across diverse cipher collections, and illustrate the workflow through a case study. The results show that this approach is practical and sample-efficient: it performs well with limited training data and remains effective in a challenging yet typical bootstrap scenario for new cipher collections. It supports human-in-the-loop correction, significantly reduces manual work, and helps produce accurate transcriptions and training data.
listelement.badge.access-status Avatud juurdepääs ,
CrypLLM: A Built-in Chat Assistant for CrypTool 2
(Tartu University Library, 2026-06-22) Kopal, Nils; Kray, Marc Phillip; Esslinger, Bernhard; Desenclos, Camille; Pierrot, Cécile
CrypLLM is a built-in chat assistant (agent) that supports users in creating and analyzing cryptographic workflows (“graphical programs”) within CrypTool 2 (CT2). This paper presents the motivation for CrypLLM and describes its integration into CT2. We further discuss several e-learning scenarios in which the agent helps users understand, construct, and troubleshoot cryptographic workflows. Finally, we outline the system architecture and summarize current limitations as well as future directions.
listelement.badge.access-status Avatud juurdepääs ,
CTTS – CrypTool Transcriber and Solver
(Tartu University Library, 2026-06-22) Lasry, George; Desenclos, Camille; Pierrot, Cécile
This document describes the CrypTool Transcriber and Solver (CTTS). It enables the transcription, decipherment, and analysis of historical ciphered documents. CTTS provides an end-to-end integrated solution for all those stages, with a convenient graphical user interface. CTTS has been successfully employed to transcribe and decipher dozens of collections of historical ciphered documents.

Sirvi

Viimati lisatud