Breaking Data Encryption Standard with a Reduced Number of Rounds Using Metaheuristics Differential Cryptanalysis

Area of Science:

• Cryptography
• Computer Science
• Artificial Intelligence

Background:

• Traditional cryptanalysis methods face challenges with complex encryption algorithms.
• Metaheuristic algorithms offer potential for optimizing cryptanalytic attacks.
• Differential cryptanalysis (DC) is a powerful technique for analyzing block ciphers.

Purpose of the Study:

• To develop and evaluate a novel metaheuristic cryptanalytic attack combining differential cryptanalysis and memetic algorithms.
• To assess the efficiency of the proposed attack against the reduced Data Encryption Standard (DES).
• To compare the performance of the new attack with existing metaheuristic and classical cryptanalytic methods.

Main Methods:

• Implementation of a memetic algorithm with simulated annealing (MASA) for enhanced local search.
• Application of differential cryptanalysis (DC) to target the last subkey of a reduced-round DES.
• Verification of the MASA attack on ciphertexts generated using a six-round DES.
• Comparative analysis of MASA against Genetic Algorithm (NGA) and classical DC attacks regarding time and memory consumption.
• Investigation of the entropy of MASA and NGA attacks.

Main Results:

• The MASA attack successfully targets the last encryption subkey of the reduced DES.
• The proposed approach significantly reduces the search space by automatically rejecting suboptimal solutions.
• MASA demonstrates competitive or superior performance compared to NGA and classical DC in terms of time and memory efficiency.
• The study provides insights into the entropy characteristics of the MASA and NGA attacks.

Conclusions:

• The developed MASA attack presents an effective and efficient method for cryptanalysis of symmetric-key algorithms like DES.
• Metaheuristic approaches, particularly MASA, offer a promising direction for advancing cryptanalytic capabilities.
• The findings contribute to the understanding of cryptanalytic attack complexities and the optimization of search strategies in cryptography.