Citation
Daud, Muhamad Azlan
(2014)
Reconstructing applicable chaotic Baptista-type symmetric cryptosystem.
Masters thesis, Universiti Putra Malaysia.
Abstract
This work, introduces a method to repair a cryptosystem based on a chaotic
dynamical system. Baptista exploited the chaotic property of the logistic equation
f(x) = b x (1 - x) to develop a cryptosystem. This cryptosystem has the ability to
produce various ciphers responding to the same message input. Alvarez through his
one-time pad attack successfully attacked the Baptista cyptosystem. Ariffin
attempted to modify the cryptosystem to enhance the security of the original
Baptista’s cryptosystem. Rhouma identified a flaw in the method Ariffin put forward,
specifically in step 4 of the encryption procedure, where it does not implement a oneto-
one operation resulting in failure to decrypt the ciphertext. The method is based on
the Fractal and Iterated System (IFS), where an in-depth study on Fractal, Chaos and
Cryptography is needed to assist in actualizing the research objectives. The algorithm
is developed to counter the one-time pad attack. This recommended encryption
algorithm also overcomes the flaw in Ariffin’s encryption procedure. The modified
Baptista type cryptosystem suffers from message expansion that goes against the
conventional methodology of a symmetric cryptosystem. As a result, we studied the
idea of Huffman encoding. We then designed a new compression algorithm
developed using ideas from the Huffman coding. Finally, the compression algorithm
is applied onto the modified Baptista cryptosystem to show a possible practical
deployment of the Baptista cryptosystem and to also produce better compression
ratio.
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