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Applications of cryptanalysis methods to some symmetric key primitives

Title:

Applications of cryptanalysis methods to some symmetric key primitives

Khajooei, Anahid (2015) Applications of cryptanalysis methods to some symmetric key primitives. Masters thesis, Concordia University.

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Abstract

Block ciphers and hash functions are important cryptographic primitives that are used to secure the exchange of critical information. With the continuous increase in computational power available to attackers, information security systems including their underlying primitives need continuous improvements. Various cryptanalysis methods are used to examine the strength and weakness of hash functions and block ciphers.
In this work, we study the Lesamnta-512 and DHA-256 hash functions and the LAC authenticated encryption scheme. In particular, we study the resistance of the underlying block cipher of the Lesamnta-512 hash function against impossible differential attacks, the resistance of the DHA-256 compression function against collision attacks. We also study MAC forgery attacks against LAC. Throughout our analysis, we use different automated methods to facilitate our analysis.
For the cryptanalysis of Lesamnta-512, two automated methods are studied for finding an impossible differential path with the maximum length. Using the obtained impossible differential path, impossible differential cryptanalysis of Lesamnta-512 is performed for 16 rounds. For the DHA-256 hash function, we used an algebraic method to find collisions for its 17-step reduced compression function by deriving difference equations for each step and then solving them when the conditions for collisions are imposed on these equations.
For LAC, the differential behavior of the different operations of the cipher is represented into a set of linear equations. Then, a Mixed Integer Linear Programming (MILP) approach is used to find a high probability characteristic. This characteristic is then used to perform a forgery attack on LAC encryption authenticated cipher.

Divisions:Concordia University > Gina Cody School of Engineering and Computer Science > Concordia Institute for Information Systems Engineering
Item Type:Thesis (Masters)
Authors:Khajooei, Anahid
Institution:Concordia University
Degree Name:M.A. Sc.
Program:Information Systems Security
Date:1 April 2015
Thesis Supervisor(s):Youssef, Amr
ID Code:980008
Deposited By: ANAHID KHAJOOEIZADEH
Deposited On:13 Jul 2015 13:20
Last Modified:19 Nov 2018 19:50
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