A. M. Youssef and S. E. Tavares Department Of Electrical and Computer Engineering Queen’s University Kingston, Ontario, Canada, K7L 3N6 Phone : (613) 545–2945 Fax : (613) 545–6615 email : [email protected] Indexing terms: Cryptography, Private-key cryptosystems, Substitution boxes, Combinatorics. Abstract Nonlinearity is a crucial requirement for the substitution boxes in secure block ciphe...

This paper presents a simple yet effective method for transforming Boolean functions that do not satisfy the strict avalanche criterion (SAC) into ones that satisfy the criterion. Such a method has a wide range of applications in designing cryptographically strong functions, including substitution boxes (S-boxes) employed by common key block encryption algorithms.

Boolean functions play an important role in cryptography. They are elementary building blocks for various cryptographic algorithms – stream ciphers, block ciphers, hash functions, etc. The most common usage for Boolean functions is the construction of larger blocks – substitution boxes [4, 5, 6]. Boolean functions used in these constructions ought to satisfy certain criteria in order to resist ...

Two signiicant recent advances in cryptanalysis, namely the diierential attack put forward by Biham and Shamir BS91] and the linear attack by Matsui Mat94a, Mat94b], have had devastating impact on data encryption algorithms. An eminent problem that researchers are facing is to design S-boxes or substitution boxes so that an encryption algorithm that employs the S-boxes is immune to the attacks....

Fundamental to the electronic security of information and communication systems, is the correct use and application of appropriate ciphers. The strength of these ciphers, particularly in their ability to resist cryptanalytic attacks, directly influences the overall strength of the entire system. The strength of the underlying cipher is reliant upon a robust structure and the carefully designed ...

In this paper, we prove that the Strong Novikov Conjecture for a residually finite group is essentially equivalent to the Coarse Geometric Novikov Conjecture for a certain metric space associated to the group. As an application, we obtain the Coarse Geometric Novikov Conjecture for a large class of sequences of expanders.

We construct several geometric representatives for the C/Zm fractional branes on either a partially or the completely resolved orbifold. In the process we use large radius and conifold-type monodromies, and provide a strong consistency check. In particular, for C/Z5 we give three different sets of geometric representatives. We also find the explicit Seiberg-duality, in the Berenstein-Douglas se...

The concepts of (∈γ ,∈γ ∨ qδ)-fuzzy h-ideals and (∈γ ,∈γ ∨ qδ)-fuzzy hinterior ideals in hemirings are introduced. Some new characterization theorems of these kinds of fuzzy h-ideals are also given. In particular, we investigate prime and strong prime (∈γ ,∈γ ∨ qδ)-fuzzy h-ideals in hemirings. Finally, we show that the h-hemiregular and h-semisimple hemirings can be described by using these kin...