Item – Theses Canada

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OCLC number
46561087
Link(s) to full text
LAC copy
LAC copy
Author
Youssef, A. M.(Amr Mohamed)
Title
Analysis and design of block ciphers.
Degree
Ph. D. -- Queen's University, 1998
Publisher
Ottawa : National Library of Canada = Bibliothèque nationale du Canada, [1999]
Description
2 microfiches.
Notes
Includes bibliographical references.
Abstract
In this thesis we study various cryptographic properties of boolean mappings from n bits to m bits. In particular, we derive expressions for the expected size of the maximum XOR table entry and the maximum Linear Approximation Table entry for some combinatorial structures of interest such as regular (balanced) mappings, and injective mappings. We derive similar expressions for the expected value of different forms of information leakage and relate different forms of information leakage to the spectral properties of the function. We also extend the definitions of many cryptographic criteria to multi-ouput boolean functions and study the relationship between the Walsh-Hadamard transform and various types of information leakage. A new construction method for highly nonlinear injective s-boxes is presented. It is shown that the resistance of CAST-like encryption algorithms (based on randomly selected substitution boxes) to the basic linear cryptanalysis was underestimated in previous work. We introduce a new class of Substitution Permutation Networks (SPNs) with the advantage that the same network can be used to perform both the encryption and the decryption operations. Different cryptographic properties of this class such as resistance to both linear and differential cryptanalysis are examined. We also present two construction methods for involution linear transformations for SPNs based on Maximum Distance Separable codes. An analytical model for the avalanche characteristics of SPNs with different linear transformation layers is developed. We also prove a conjecture by Cusick regarding the number of functions satisfying the Strict Avalanche Criterion.
ISBN
0612278646
9780612278646