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Journal of Discrete Mathematical Sciences and Cryptography cover
Hybrid ·Peer-reviewed·ISSN (Online): 2169-0065·ISSN (Print): 0972-0529

Monthly Journal: Publishes theoretical and applied research in all areas of Discrete Mathematical Sciences, Cryptography, Combinatorics, Elliptic Curves and Information Security.

Issues up to 2022 co-published with and available at:Taylor & Francis Online
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Open Access Research Article

A modified ElGamal-like cryptosystem

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pp. 631–639Vol. 28Issue 3April 2025DOI: 10.47974/JDMSC-1723 Crossmark XML
Received:
05 May 2021
Accepted:
07 Sep 2021
Published Online:
11 Apr 2025
Article type:
Research Article
Language:
EN
Article no.:
JDMSC-1723
Pages:
631–639

Abstract

The ElGamal cryptosystem stands as one of the foremost public key encryption methods and represents a probabilistic algorithm, originating from the framework of the Diffie-Hellman key exchange protocol. Diverging from the Diffie-Hellman approach, ElGamal cryptosystem constitutes a comprehensive encryption-decryption scheme hinging on the discrete logarithm problem for its security. Its robustness is rooted in the formidable challenge of computing the discrete logarithm modulo a substantially large prime number. In this study, a variation of the ElGamal algorithm was introduced using matrices. The key generation of the new system is different from that of the standard ElGamal Cryptosystem. Here, our generator is a 2×2 matrix containing four primitive roots of the selected prime number. The Plaintext is considered in uppercase letters and then converted into uppercase and lowercase letters alternatively. ASCII alphabet is used to obtain the corresponding numerical values for each letter and decomposed into blocks of 2×2 matrices. The security of this system rests on the intrinsic complexity of the discrete logarithm problem, a computational challenge well-documented for its arduousness. Additionally, our proposed system maintains resilience against Chosen Plaintext Attacks (CPA), further bolstering its security posture.

Keywords

Subject Classifications

11Z0511A0711T7194A60

References

[1] W. Diffie and M. Hellman, “New directions in Cryptography,” IEEE transactions on Information Theory, vol. 22, no. 6, pp. 644-654 (1976).
[2] T. ElGamal, “A public key cryptosystem and a signature scheme based on Discrete logarithms,” IEEE transactions on information theory, vol. 31, no. 4, pp. 469-472 (1985).
[3] A. Abusukhon, M. N. Anwar, Z. Mohammad, and B. Alghannam, “A hybrid network security algorithm based on diffie hellman and text-to-image encryption algorithm,” Journal of Discrete Mathematical Sciences and Cryptography, vol. 22, no. 1, pp. 65-81 (2019).
[4] R. Ranasinghe and P. Athukorala, “A generalization of the Elgamal public-key cryptosystem,” Journal of Discrete Mathematical Sciences and Cryptography (2021) (Published Online, URL : https://doi.org/10.1080/09720529.2020.1857902).
[5] J. Katz and Y. Lindell, Introduction to Modern Cryptography. CRC Press (2021).

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