<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>Polybius cipher is a special substitution system widely used during history. In our research, we found several Polybius-like ciphers used in Czecho-slovakia and in the Slovak State from the first half of the 20th century. Various types of this cipher are described in the first Czechoslovak cryptanalysis manual “šifrovací systémy a návod k luštění kryptogramů” by plk. Josef Růžek. It can be also found in the official cryptology directive called G–VII–8 “šifrování” (encryption) from 1938, and another variant in the new version of the same directive from 1946. In this work, we focus on a special Polybius-like cipher inspired by three real ciphers used in Czechoslovakia and in the Slovak State. Two were used during WW2 and one right after the war. We will show how these ciphers were used and how they can be solved with a modern heuristic approach on a personal computer. We evaluate the effectiveness of the Hill-Climbing heuristic methods with restarts. We also investigated several different fitness functions and language models.</p>
</abstract>

Polybius cipher is a special substitution system widely used during history. In our research, we found several Polybius-like ciphers used in Czecho-slovakia and in the Slovak State from the first half of the 20th century. Various types of this cipher are described in the first Czechoslovak cryptanalysis manual “šifrovací systémy a návod k luštění kryptogramů” by plk. Josef Růžek. It can be also found in the official cryptology directive called G–VII–8 “šifrování” (encryption) from 1938, and another variant in the new version of the same directive from 1946. In this work, we focus on a special Polybius-like cipher inspired by three real ciphers used in Czechoslovakia and in the Slovak State. Two were used during WW2 and one right after the war. We will show how these ciphers were used and how they can be solved with a modern heuristic approach on a personal computer. We evaluate the effectiveness of the Hill-Climbing heuristic methods with restarts. We also investigated several different fitness functions and language models.

Cryptanalysis of a Special Polybius-Like Cipher Using Hill-Climbing

Slovak University of Technology in Bratislava

Tatra Mountains Mathematical Publications

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

{"article-title":"Cryptanalysis of a Special Polybius-Like Cipher Using Hill-Climbing"}

Polybius cipher is a special substitution system widely used during history. In our research, we found several Polybius-like ciphers used in Czecho-slovakia...

Cryptanalysis of a Special Polybius-Like Cipher Using Hill-Climbing

Published Online: Dec 09, 2023

Page range: -

Received: Sep 29, 2022

Accepted: Sep 22, 2023

DOI: https://doi.org/10.2478/tmmp-2023-0032

Keywords
Military history, Slovakia, Czechoslovakia, Historical ciphers, Polybius cipher, Polybius checkerboard, Cryptanalysis, Hill-Climbing, Language models

© 2023 Eugen Antal, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Cryptanalysis of a Special Polybius-Like Cipher Using Hill-Climbing

Published Online: Dec 09, 2023

Page range: -

Received: Sep 29, 2022

Accepted: Sep 22, 2023

DOI: https://doi.org/10.2478/tmmp-2023-0032

KeywordsMilitary history, Slovakia, Czechoslovakia, Historical ciphers, Polybius cipher, Polybius checkerboard, Cryptanalysis, Hill-Climbing, Language models

© 2023 Eugen Antal, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
Military history, Slovakia, Czechoslovakia, Historical ciphers, Polybius cipher, Polybius checkerboard, Cryptanalysis, Hill-Climbing, Language models