Keys with nomenclatures in the early modern Europe

Abstract

We give an overview of the development of European historical cipher keys originating from early Modern times. We describe the nature and the structure of the keys with a special focus on the nomenclatures. We analyze what was encoded and how and take into account chronological and regional differences. The study is based on the analysis of over 1,600 cipher keys, collected from archives and libraries in 10 European countries. We show that historical cipher keys evolved over time and became more secure, shown by the symbol set used for encoding, the code length and the code types presented in the key, the size of the nomenclature, as well as the diversity and complexity of linguistic entities that are chosen to be encoded.

Keywords:

• Cryptanalysis
• cipher keys
• DECRYPT project
• historical cryptology
• nomenclatures

Acknowledgments

This work has been supported by the Swedish Research Council, grant 2018-06074: DECRYPT—Decryption of historical manuscripts.

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Notes

1 https://www.cryptool.org/en/ct2/

2 https://hcportal.eu/

3 http://cryptiana.web.fc2.com/code/crypto.htm

4 http://www.cipherbrain.de

Additional information

Notes on contributors

Beáta Megyesi

Beáta Megyesi is a professor of computational linguistics at Uppsala University, Sweden. She specializes in digital philology, historical cryptology, and natural language processing. Her research interests include the automatic analysis of nonstandard language data to allow large-scale empirical studies for the humanities and social sciences. She is the former president of the Northern European Association for Language Technology, former head of the department of Linguistics and Philology and campus director of the English Park Campus at Uppsala University. She serves as the PI of the DECODE and DECRYPT projects, aiming at the development of infrastructural resources and tools for historical cryptology.

Crina Tudor

Crina Tudor is a research assistant in computational linguistics with Uppsala University, Sweden. Her research interests are centered around digital philology, natural language processing and historical text processing. She started her work with the DECRYPT project by creating a tool that examines the structure of historical cipher keys, and has since continued to do research focusing on the analysis and transcription of historical keys and nomenclatures. She is also currently working on developing a specialized search tool for Labor’s Memory, a project that handles the digitization of historical Swedish labor union documents.

Benedek Láng

Benedek Láng A historian and a medievalist (PhD, Central European University, 2003), Benedek Láng is a professor at ELTE, Budapest. He is a historian of science and specializes in late medieval manuscripts of learned magic and early modern secret communication (artificial languages and cipher systems). His scholarly books include Unlocked Books, Manuscripts of Learned Magic in the Medieval Libraries of Central Europe (Penn State University Press, 2008), Real Life Cryptology (Amsterdam University Press, 2018), and The Rohonc Code (Penn State University Press, 2021).

Anna Lehofer

Anna Lehofer is an economist on regional and urban planning who writes her PhD in the topic of cryptology at Budapest University of Technology and Economics (Hungary). She is interested in historical cryptology and her research focuses on decryption methodologies for early modern ciphers, especially on hierarchical clustering. In the DECRYPT project she takes part in archival collection and historical analysis.

Nils Kopal

Nils Kopal is a computer scientist and cryptanalyst working as a Postdoc at the University of Siegen, Germany. He specializes in cryptanalysis of classical ciphers and distributed cryptanalysis. He is leading the development of the open-source software CrypTool 2. In the DECRYPT project he is responsible for developing tools for cryptanalysis of historical and classical ciphers and integrating these in the DECRYPT pipeline and CrypTool 2.

Karl de Leeuw

Karl de Leeuw is an intelligence historian and wrote his PhD on the History of Cryptology in the Netherlands at the University of Amsterdam. He published extensively about this subject in journals, such as Cryptologia (1993, 1995, 2001, 2003, 2013, 2015), The Historical Journal (1999), Diplomacy & Statecraft (1999), Intelligence & National Security (2015), Yearbook of the Grimmelshausengesellschaft (2014) and ISIS (2019). He acted as editor of the History of Information Security. A comprehensive Handbook (2007). Karl de Leeuw passed away on July 14, 2022.

Michelle Waldispühl

Michelle Waldispühl is an associate professor in German linguistics and language education at the Department of Languages and Literatures, University of Gothenburg, Sweden. She is a historical linguist specialized in philology, Germanic language history, and the linguistics of writing. Her current research interests include spelling variation, historical sociolinguistics and multilingualism with a particular focus on onomastics, runic studies, and cryptography.