Modern Graphical User Interface Application With PYQT5 For The Classic Caesar Encryption Algorithm

In this study, the classical Caesar cypher algorithm, recognised for its historical significance and as a fundamental teaching tool in the field of cryptography, is comprehensively re-examined in the context of modern software engineering techniques and security paradigms. Given the increasing threats to data security in the digital age, the weaknesses of simple, static-key-based classical encryption methods have become apparent. This study focuses on addressing these shortcomings and modernising the algorithm in terms of security and usability. The methodology of the study starts with a detailed analysis of the mathematical foundations of the Caesar algorithm based on modular arithmetic. It covers a wide range of topics, including the development of a dynamic shift mechanism based on keywords. Multilingual text processing and normalisation techniques compliant with the Unicode standard were used to make the texts suitable for worldwide use. Cryptanalysis methods based on brute-force attack simulations and frequency analyses were used to identify the algorithm's vulnerabilities and assess its security. At the application level, a system with two modules is presented that was developed using the Python programming language. This is a terminal-based advanced command line tool and an interactive graphical user interface (GUI) developed with the PyQt5 library. This architecture allows both experienced users to perform detailed parameter checks and a broader user base to have an intuitive and visually supported learning experience. Performance analyses have shown that the processing time of the algorithm increases linearly with text length, and have confirmed the practicality of real-time encryptionand decryption operations. User experience studies have shown that the GUI-based interface is highly motivating and user-friendly. The study's modular and object-orientated design provides a solid foundation for future algorithm integrations and security enhancements. Its open-source structure offers extension possibilities for academic and industrial research.