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Showing 3 results for Hash Function
Zahra Zolfaghari, Nasour Bagheri,
Volume 6, Issue 1 (9-2017)
Abstract
In this article, we introduce Time Memory Trade Off attack and a method for finding near collisions in a hash function. By considering hash computations, it is easy to compute a lower bound for the complexity of near-collision algorithms, and to construct matching algorithm. However, this algorithm needs a lot of memory, and uses memory accesses. Recently, some algorithms have been proposed that do not require this amount of memory. They need more hash evaluation, but this attack is actually more practical. These algorithms can be divided in two main group: the first group is based on truncation and the second group is based on covering codes. In this paper, we consider the first group that is based on truncation. For practical implementation, it can be assumed that some memory is available, Leurent [10] showed that it is possible to reduce the complexity significantly by using this memory. In the next step, Sasaki et al. [9] proposed improvement of most popular Time Memory Trade off for K-tree algorithm by using multi-collision based on Helman’s table. As a result, they obtained new trade off curve that for k=4 the tradeoff curve will be . In this article, at the first the methods of TMTO, and then the method of finding near-collision by using TMTO are explained.
, , ,
Volume 8, Issue 1 (9-2019)
Abstract
Designing a wide range of encryption algorithms using the sponge structure is reduced only by designing a transform or permutation. Designer specifies a transformation or permutation and then form a hash function, stream cipher, authenticated encryption algorithm and pseudo random number generator. Also, exploiting one single transformation or permutation simplifies the implementation of derived algorithms and gives other advantages such as provable security and better understanding of security of designs. This paper provides a quick introduction to design the sponge structure and explains some cryptographic applications and security requirements.
Seyed Hesam Odin Hashemi, Mohammad Hassan Majidi,
Volume 13, Issue 2 (12-2024)
Abstract
With the ever-increasing growth of the Internet and the expansion of imaging tools, digital images are a huge part of the information we work with. This information often contains sensitive data that requires protection. This paper presents a chaotic image encryption method that effectively safeguards the information contained within digital images. The IEPS encryption system is an image encryption scheme based on a Piecewise linear chaotic map (PWLCM) and the SHA-512 hashing function. This design incorporates two operations: permutation and substitution of image pixels. In the permutation stage, the PWLCM map is employed, and the features of the SHA-512 are utilized to substitute the pixels. The experimental results demonstrate that the PWLCM encryption algorithm successfully encrypts the information within the image and exhibits robust performance against various analyses, including the entropy, histogram, key sensitivity criterion, and resistance to differential attacks.
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