What Was Encoded in Historical Cipher Keys in the Early Modern Era?

Keys with nomenclatures in the early modern Europe

“…(Kahn 2008, p. 58) Nothing is known about the number of aperitifs consumed by the historians doing research in the archives, but Kahn's words were not in vain. The proposed project was done by several scholars on the basis of the archival materials of various geographical areas: L ang for the Central European area (L ang 2015, 2018), Lasry, Megyesi, and Kopal did it for the early modern papal correspondence (Lasry, Megyesi, and Kopal 2021), and the authors of the present article provided a first larger quantitative analysis on 700 cipher keys (Megyesi et al 2021) and a more recent, detailed study on the plaintext elements in 1,384 keys (Megyesi et al 2022).…”

“…Megyesi et al (2021) undertook a task similar to that of the present article: a systematic analysis of 700 cipher keys collected at that time in the Decode database (Megyesi, Blomqvist, and Pettersson 2019) focusing on the symbol system, languages, nulls, and code types. A year later, the authors continued with studies of the plaintext entities in nomenclatures encoded in 1,384 keys (Megyesi et al 2022). The two articles can be seen as previous steps of the present research in two senses: the first being carried out on a limited set of keys, and the second investigating only part of the components of the keys.…”

“…The two articles can be seen as previous steps of the present research in two senses: the first being carried out on a limited set of keys, and the second investigating only part of the components of the keys. To our knowledge, the studies by Megyesi et al (2021Megyesi et al ( , 2022 were the first that used large scale statistics to analyze the trends and the morphology of 1 https://www.cryptool.org/en/ct2/ the cipher keys but none of them involved the entire nomenclatures of a significantly bigger dataset, making the present study more representative and exhaustive than the previous ones.…”

“…The present paper builds on the earlier results, but is much more ambitious. First, the empirical basis of the research has considerably grown (from 700 to 1,600) and became more balanced over centuries, and second, the scope includes not only the plaintext elements as in Megyesi et al (2022), but the entire nomenclatures as well.…”

“…Nomenclatures typically include named entities (NE), such as persons and locations (Megyesi et al 2022). In the sample of this study, only 3.8% of the nomenclatures do not contain named entities.…”