Chaotic Electronic Circuits in Cryptography
Matej alamon · Applied Cryptography and Network Security · 2012
The third chapter deals with a usage of chaotic circuits in cryptography.The subsequent sub-chapters describe three basic analog encryption techniques and the structures of a chaos based digital cryptographic system.The fourth chapter describes the example of digital chaotic cryptosystem with the previously chosen variant of the Chua's circuit.In the sub-chapters are described details of used encryption function and the structure of the entire cryptographic system, adapted for a digital images encryption.In the continuation the cryptanalysis of the described cryptographic system is also presented.Analysis of ciphertexts histograms points out the problem of not uniformly distributed pseudo-chaotic sequences.We have presented also the solution that assures a uniform distribution of pseudo-chaotic sequences.Further we have analysed the statistical and correlation properties of ciphertexts, obtained with different secret keys.Therefore, we performed the auto-covariance and cross-covariance analysis.The problem of a slow initial divergence of pseudo-chaotic sequences is also emphasised.This problem is very evident by an encryption with very similar secret keys.The last fifth chapter is assigned to the summary of findings and possibilities to solve some problems of the so called chaotic cryptography. Chaotic behaviour of electronic circuitsElectronic circuits can generally be linear or non-linear.As no complete linearity exists in the real world, all circuits are actually non-linear.Their analysis is usually mathematically difficult as it is linked to solving non-linear differential equations.