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ElGamal Cryptosystem for Image Encryption and Decryption

Bheesetti Narasimha Bhaskar  ,  P. Bindhu Priya

Assistant Professor, Training & Placement Officer, 2 MCA Final Semester,

Master of Computer Applications,

Sanketika Vidya Parishad Engineering College, Vishakhapatnam, Andhra Pradesh, India.

Abstract:

The ElGamal cryptosystem is one of the most well-known public-key encryption algorithms due to its ability to generate different ciphertexts for the same plaintext on successive runs. However, the standard ElGamal approach often results in ciphertexts that occupy significantly more memory than the original plaintext, making it inefficient for data types such as images, where size preservation is important. To address this limitation, this paper proposes an enhanced ElGamal cryptosystem optimized for digital data, including text and image formats. The system introduces a modified key generation mechanism combined with pixel-level encryption transformations to reduce redundancy and increase security. The implementation, developed using Python and OpenCV, demonstrates that the enhanced ElGamal approach can securely and efficiently encrypt image data while maintaining usability for practical applications.

Index Terms — Cryptography, ElGamal, Image Encryption, XOR, Public Key, Python, Tkinter, Gaussian Key, Secure Communication.