Many historians and linguists are working individually and in an uncoordinated fashion on the identification and decryption of historical ciphers. This is a time-consuming process as they often work without access to automatic methods and processes that can accelerate the decipherment. At the same time, computer scientists and cryptologists are developing algorithms to decrypt various cipher types without having access to a large number of original ciphertexts. In this paper, we describe the DECRYPT project aiming at the creation of resources and tools for historical cryptology by bringing the expertise of various disciplines together for collecting data, exchanging methods for faster progress to transcribe, decrypt and contextualize historical encrypted manuscripts. We present our goals and work-in progress of a general approach for analyzing historical encrypted manuscripts using standardized methods and a new set of state-of-the-art tools. We release the data and tools as open-source hoping that all mentioned disciplines would benefit and contribute to the research infrastructure of historical cryptology.

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This article presents three newly rediscovered encrypted Habsburg letters that were sent by Maximilian II to his Polish delegates in 1575. We describe the process of deciphering and the principles and peculiarities of the cipher from a cryptographic perspective. Furthermore, content and historical and linguistic context of the letters are explained. The records are held at the € Osterreichisches Haus-, Hof-und Staatsarchiv and were collected and deciphered in the context of the interdisciplinary and international research project "DECRYPT-Decryption of historical manuscripts". For cryptanalysis the open-source e-learning program CrypTool 2 was used. The article is the result of a joint effort of a computer scientist and a historical linguist.

This paper addresses the Anglo-Saxon personal name inscriptions at Monte Sant' Angelo in Southern Italy from a sociolinguistic angle. The main interest lies in the mix between Roman and runic writing and its inter pretation in the light of indi vidual literacy and the cultural context of medieval pilgrimage. Four from a total of five inscriptions were written in runes; two of these show sig nifi cant in fluence from Anglo-Saxon scribal practices and Roman epi graphic writ ing. The fifth Anglo-Saxon name is written entirely in Roman letters. Draw ing on theo retical approaches from modern sociolinguistic studies of multi lin gualism in writ ing, this study suggests that the use of mixed Roman-runic prac tices reflects the biscriptal background of the respective carvers and was applied in situ to indi vidualize the inscriptions. However, not all the in scrip tions show such a mix; hence either skill or personal preference varied among the pilgrims. The prac tice of mixing evident in the runic inscriptions does not fully correspond to previ ously described features of multilingual and multi scrip tal writing, which is why a new term, "heterographia", has been coined in this study to include mix ing not only in a language and a writing system, but also on a graphetic and ortho graphic level. Finally, the use of runes or Roman script for one's personal name is inter preted as an expression of social identity dependent on the person's social embedding.

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.