As the space for digital communication expands, there is even greater need for accessibly simple, transparent, and computationally economical encrypting tools to back up the more operationally challenging ones, like AES and RSA. This article outlines the architecture, implementation and systematic security analysis of a python application with graphical user interface (GUI) in realisation of a hybrid cryptographic pipeline using text cryptography and text transport encoding with a hybrid integrity hashing, the Vigenère polyalphabetic cipher, Base64 encoding and hash generation using SHA-256, respectively. The application is made with Python's GUI library (Tkinter), which makes it run without any external libraries across different operating systems. Four experimental dimensions were considered: (i) the benchmark of computational throughput with classical and modern symmetric cryptographic ciphers; (ii) statistical analysis of Shannon entropy for different categories of messages and Index of Coincidence (IC); (iii) modelling of the sensitivity to key size and resistance to brute force; and (iv) comparative analysis of the multi-dimensional security profile using radar chart. Experimental results demonstrate that for the proposed system keys of length 16 or more yield ciphertext entropy between 5.89 bits/byte and 6.11 bits/byte and IC ranging from 0.037 to 0.041, respectively, closely matching the statistical profile of the statistically random text. In a worst model of 10 attacks per second, theoretical “brute force” time to break the system is > 6 x 10²? years at a key length of 32 characters. The latency of encryption for a 10 KB plaintext is 3.7 ms, which is 3.1-fold overhead over AES-128-GCM — acceptable for the application areas considered. The system is deliberately designed for educational use, low sensitivity inter-system messaging and legacy protocol integration in cases where integration with the AES library is impractical. Formal security restrictions, among other things the lack of IND-CPA guarantees, are characterised and possibilities for mitigation are discussed.
Keywords : Vigenère Cipher, Base64 Encoding, Polyalphabetic Substitution Cipher , Brute-Force Resistance.
Authors : V Hema Sree , P Viswanatha Reddy , M Anjan Kumar , Praveen Naik , Murali Mohan Cheepu
Title : Design and Security Evaluation of a Hybrid Text Encryption Framework Using Vigenère Cipher, Base64 Encoding, and SHA-256 Integrity Verification: A Graphical User Interface Implementation
Volume/Issue : 2025;2(3 ( July - September ))
Page No : 29 - 34