Implementation of a Symmetric Chaotic Encryption Scheme

Voice over Internet Protocol technology (VoIP) is progressing commendably, but packet
loss, propagation delay, jitter, unreliable IP networks, and vulnerability to attacks by
Internet hackers are among critical issues that have been identified. Voice privacy and
security needs to focused upon and data encryption techniques are the answers in
providing the security needed. However, traditional cryptosystems demand high
computational complexity andhigh digital signal processors which in return increases the
cost of implementation.
There is parallel growth in cryptographic techniques which originated anintense research
activity and the search for new directions in cryptography such as chaotic encryption.
Due to its deterministic nature and its sensitivity to initial conditions, chaos has a certain
potential in creating a newway of securing information to be transmitted or stored.
There are two main objectives to this project. First is study the feasibility of the chaotic
encryption scheme in providing a solution in to preserve data security while maintaining
the voice quality for voice over Internet Protocol. Secondly, a new scheme based on a
chaos system will be implemented for voice data. In order to achieve the second
objective, a study had been carried out on other proposed schemes mainly the
Hierarchical Data Security Protection (HDSP) for VoIP. This scheme performs two main
operations which is the data-frame interleaving and intra-frame data encryption using bit
swapping. Based onthe HDSP scheme, the author suggests a new scheme using two level
encryption techniques, based on chaos. In this scheme, the author uses the bit swapping
technique as the second encryption-decryption level and enhances it with a first level
encryption-decryption scheme using the two's compliment overflow nonlinearity
encoder-decoder pair.
The implementation ofthis scheme is specified to do real time processing ofvoice data. It
can also be used to read, encrypt and write a wave file. The entire system is implemented,
tested and validated using MATLAB and Visual C++.
Due to the promising prospect ofchaotic encryption in the field ofcryptography, and the
lack ofimplementation ofthis new encryption-decryption algorithm, this project focuses
on introducing a new symmetric encryption-decryption scheme based on a chaos system
for VoIP.