Comparative Analysis of Stream Ciphers: From the Vernam Cipher to Modern Cryptographic Algorithms

Abstract

This thesis presents a comparative analysis of stream ciphers, from the historical Vernam cipher to modern cryptographic algorithms. It reviews the theoretical foundations of stream encryption and explains the internal design principles of key ciphers such as RC4, Grain, Trivium, Salsa20, and ChaCha20. The work includes practical Python implementations and a benchmarking framework to evaluate encryption speed, memory usage, and initialization cost. The results highlight clear differences between legacy and modern designs in both performance and security resilience. Security analysis is combined with implementation results to provide practical recommendations for real-world use cases. The thesis concludes that modern ARX-based ciphers, especially ChaCha20, offer the best balance of efficiency, robustness, and deployment suitability.