Abstract The history, operating principles, strengths, and weaknesses, of the German cipher machine Enigma, have been widely studied for almost 50 years. Even though Bletchley Park regularly broke Enigma encrypted traffic during World War II, new pieces of information and fresh analysis are still aggregated to the remarkable “puzzle” called Enigma. This paper shows that Enigma’s plugboard is vulnerable to Genetic Algorithm (GA) attacks, which solves Enigma’s plugboard faster than earlier published ciphertext-only techniques. The Genetic Algorithm does this using the counting measure Index of Coincidence (IC). Independently of the GA, but related to the analysis, we introduce a new measure Progress Index of Coincidence (PIC). PIC is a measure of the relative progress in decryption between the ciphertext and plaintext measured by IC.
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Genetic algorithm attack on Enigma’s plugboard
Semantic Scholar · Computer Science · 2020
Abstract
Abstract The history, operating principles, strengths, and weaknesses, of the German cipher machine Enigma, have been widely studied for almost 50 years. Even though Bletchley Park regularly broke Enigma encrypted traffic during World War II, new pieces of information and fresh analysis are still aggregated to the remarkable “puzzle” called Enigma. This paper shows that Enigma’s plugboard is vulnerable to Genetic Algorithm (GA) attacks, which solves Enigma’s plugboard faster than earlier published ciphertext-only techniques. The Genetic Algorithm does this using the counting measure Index of Coincidence (IC). Independently of the GA, but related to the analysis, we introduce a new measure Progress Index of Coincidence (PIC). PIC is a measure of the relative progress in decryption between the ciphertext and plaintext measured by IC.