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Modifying Blowfish Algorithm Using Permutation Techniques

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Modifying Blowfish Algorithm Using Permutation Techniques

24th International Symposium INFOTEH-JAHORINA, INFOTEH 2025

作者： Wenceslao, Jon Laurence B. Wenceslao, Felicisimo V. Cerna, Patrick D. Northern Iloilo State University College of Information and Computing Studies Estancia Iloilo Philippines State University of Northern Negros Graduate Programs Negros Occidental Philippines

ISBN: (纸本)9798331515799

This paper proposes a modified version of the Blowfish Algorithm using permutation techniques. These techniques are key parts of the F-function of the algorithm. The first modification is in the bit operations while the second part employs the cyclical Shift Rows operation. We conducted simulations to test the security strength of the modified Blowfish Algorithm in changing one bit from two input strings. The avalanche effect showed 54.687% and 53.125% changes in the output bits thus making our model secure. We also tested the execution performance of the original Blowfish Algorithm and the modified Blowfish Algorithm in the encryption and decryption processes. While the original version performs better than the modified version, no statistical difference was found between the two versions. © 2025 IEEE.

关键词： encryption algorithms

Efficient algorithms for Isogeny Computation on Hyperelliptic Curves: Their Applications in Post-Quantum Cryptography

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arXiv 2025年

作者： El Baraka, Mohammed Ezzouak, Siham Faculty of Sciences Dhar Al Mahraz Sidi Mohammed Ben Abdellah University Fez Morocco

We present efficient algorithms for computing isogenies between hyperelliptic curves, leveraging higher genus curves to enhance cryptographic protocols in the post-quantum context. Our algorithms reduce the computational complexity of isogeny computations from O(g4) to O(g3) operations for genus 2 curves, achieving significant efficiency gains over traditional elliptic curve methods. Detailed pseudocode and comprehensive complexity analyses demonstrate these improvements both theoretically and empirically. Additionally, we provide a thorough security analysis, including proofs of resistance to quantum attacks such as Shor’s and Grover’s algorithms. Our findings establish hyperelliptic isogeny-based cryptography as a promising candidate for secure and efficient post-quantum cryptographic systems. © 2025, CC BY.

关键词： encryption algorithms

Lattice Based Crypto Breaks in a Superposition of Spacetimes

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arXiv 2025年

作者： Aggarwal, Divesh Agrawal, Shashwat Kumar, Rajendra National University of Singapore Singapore Indian Institute of Technology Delhi India

We explore the computational implications of a superposition of spacetimes, a phenomenon hypothesized in quantum gravity theories. This was initiated by Shmueli (2024) where the author introduced the complexity class BQPOI consisting of promise problems decidable by quantum polynomial time algorithms with access to an oracle for computing order interference. In this work, it was shown that the Graph Isomorphism problem and the Gap Closest Vector Problem (with approximation factor O(n3/2)) are in BQPOI. We extend this result by showing that the entire complexity class SZK (Statistical Zero Knowledge) is contained within BQPOI. This immediately implies that the security of numerous lattice based cryptography schemes will be compromised in a computational model based on superposition of spacetimes, since these often rely on the hardness of the Learning with Errors problem, which is in SZK. © 2025, CC BY.

关键词： encryption algorithms

Electromagnetic Side-Channel Analysis of PRESENT Lightweight Cipher

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arXiv 2025年

作者： Gunathilake, Nilupulee A. Lo, Owen Buchanan, William J. Al-Dubai, Ahmed Blockpass ID Lab Edinburgh Napier University United Kingdom

Side-channel vulnerabilities pose an increasing threat to cryptographically protected devices. Consequently, it is crucial to observe information leakages through physical parameters such as power consumption and electromagnetic (EM) radiation to reduce susceptibility during interactions with cryptographic functions. EM side-channel attacks are becoming more prevalent. PRESENT is a promising lightweight cryptographic algorithm expected to be incorporated into Internet-of-Things (IoT) devices in the future. This research investigates the EM side-channel robustness of PRESENT using a correlation attack model. This work extends our previous Correlation EM Analysis (CEMA) of PRESENT with improved results. The attack targets the Substitution box (S-box) and can retrieve 8 bytes of the 10-byte encryption key with a minimum of 256 EM waveforms. This paper presents the process of EM attack modelling, encompassing both simple and correlation attacks, followed by a critical analysis. © 2025, CC BY.

关键词： encryption algorithms

Enhanced algorithms for the Representation of integers by Binary Quadratic forms: Reduction to Subset Sum

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arXiv 2025年

作者： Mamah, Maher Department of Mathematics The Pennsylvania State University University Park United States

In this paper, we give efficient algorithms for solving the Diophantine equation f(x, y) = m for arbitrary definite binary quadratic form f, given the factorization of m. While Cornacchia’s algorithm to solve x2 + dy2 = m provides an efficient method in many cases, its running time becomes exponentially large when m is highly composite, and inherits some subtleties when generalizing to arbitrary form f. To address these issues, we show how to reduce the problem to an instance of the Subset-Sum, a weakly NP-complete problem, allowing for more efficient solutions. Leveraging this approach, we develop deterministic algorithms that adapt to different cases based on disc(f) and m. In particular, when |disc(f)| = polylog(m), we provide a polynomial-time solution that remains efficient regardless of the structure of m. For more general cases, we present an algorithm that improves upon Cornacchia’s method, achieving a quadratic speedup. Recently, the problem of representation by a form f found important applications in elliptic curves and isogeny-based cryptography, where these algorithms are central to solving norm form *** Codes 11Y16 (primary), 11Y40 (secondary) © 2025, CC BY.

关键词： encryption algorithms

Improving Algorithmic Efficiency using Cryptography

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arXiv 2025年

作者： Vaikuntanathan, Vinod Zamir, Or MIT United States Tel Aviv University

Cryptographic primitives have been used for various non-cryptographic objectives, such as eliminating or reducing randomness and interaction. We show how to use cryptography to improve the time complexity of solving computational problems. Specifically, we show that under standard cryptographic assumptions, we can design algorithms that are asymptotically faster than existing ones while maintaining correctness. As a concrete demonstration, we construct a distribution of trapdoored matrices with the following properties: (a) computationally bounded adversaries cannot distinguish a random matrix from one drawn from this distribution, and (b) given a secret key, we can multiply such a n × n matrix with any vector in near-linear (in n) time. We provide constructions both over finite fields and the reals. This enables a broad speedup technique: any algorithm relying on a random matrix—such as those using various notions of dimensionality reduction—can replace it with a matrix from our distribution, achieving computational speedups while preserving correctness. © 2025, CC BY-NC-ND.

关键词： encryption algorithms

Cryptoanalysis of a tropical triad matrix semiring key exchange protocol

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arXiv 2025年

作者： Sanchez, Alvaro Otero Universidad de Almería Carretera de Sacramento s/n La Cañada de San Urbano Almería04120 Spain

This article analyzes a key exchange protocol based on the triad tropical semiring, recently proposed by Jackson, J. and Perumal, R. We demonstrate that the triad tropical semiring is isomorphic to a circulant matrix over tropical numbers. Consequently, matrices in this semiring can be represented as tropical matrices. As a result, we conduct a cryptanalysis of the key exchange protocol using an algorithm introduced by Sulaiman Alhussaini, Craig Collett, and Sergĕı Sergeev to solve the double discrete logarithm problem over tropical matrices. © 2025, CC BY.

关键词： encryption algorithms

The regular multivariate quadratic problem

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arXiv 2025年

作者： Joux, Antoine Mora, Rocco CISPA Helmholtz Center for Information Security Germany

In this work, we introduce a novel variant of the multivariate quadratic problem, which is at the core of one of the most promising post-quantum alternatives: multivariate cryptography. In this variant, the solution of a given multivariate quadratic system must also be regular, i.e. if it is split into multiple blocks of consecutive entries with the same fixed length, then each block has only one nonzero entry. We prove the NP-completeness of this variant and show similarities and differences with other computational problems used in cryptography. Then we analyze its hardness by reviewing the most common solvers for polynomial systems over finite fields, derive asymptotic formulas for the corresponding complexities and compare the different approaches. Copyright © 2025, The Authors. All rights reserved.

关键词： encryption algorithms

Optimal Computational Secret Sharing

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arXiv 2025年

作者： Aureliano, Igor L. Cohen, Alejandro D’Oliveira, Rafael G.L. Institute of Mathematics Statistics and Scientific Computing University of Campinas SP Brazil Faculty of Electrical and Computer Engineering Technion–Institute of Technology Haifa Israel School of Mathematical and Statistical Sciences Clemson University ClemsonSC United States

In (t, n)-threshold secret sharing, a secret S is distributed among n participants such that any subset of size t can recover S, while any subset of size t − 1 or fewer learns nothing about it. For information-theoretic secret sharing, it is known that the share size must be at least as large as the secret, i.e., |S|. When computational security is employed using cryptographic encryption with a secret key K, previous work has shown that the share size can be reduced to (formula presented). In this paper, we present a construction achieving a share size of (formula presented). Furthermore, we prove that, under reasonable assumptions on the encryption scheme — namely, the non-compressibility of pseudorandom encryption and the non-redundancy of the secret key — this share size is optimal. Copyright © 2025, The Authors. All rights reserved.

关键词： encryption algorithms