| The objective of this thesis is to design, implement, statistically test and cryptanalyze several stream ciphers that are based on the multi-map orbit hopping mechanism - Mmohom.;We propose Mmohom as a generic method to design stream ciphers. We discuss its cryptographic properties of period, density functions, and conjugate permutations. The applications of the Mmohom result in three kinds of stream ciphers.;The first kind is Mmohocc (Multi-map orbit hopping chaotic cipher). Since its inception, chaos has been connected with cryptography due to its confusion and diffusion, which are the two important properties of a secure cipher. On top of these properties, we apply Mmohom to multiple chaotic systems in order to build Mmohocc, which greatly accelerates the chaos behavior and makes chaos more suitable for cryptographic purposes. The implementation details of the cipher are given. For the generated keystreams we get satisfactory statistical results from two batteries of the most popular and stringent statistical tests. Cryptanalysis shows that the cipher is resistant against the most known attacks.;The second kind is the Mmohom-LFSR-based cipher. Mmohom is used in conjunction with multiple LFSRs (Linear Feedback Shift Register) to destroy the linearity of the LFSRs. Cryptanalysis against algebraic attack is discussed.;The third one is Mmohoct (Multi-map orbit hopping cipher by T-functions). The T-function has maximal single cycle property, meanwhile it has some undesired algebraic patterns. We introduce the Mmohom to destroy the unwanted properties and build two experimental Mmohoct ciphers. Cryptanalysis and performance are discussed, too. |
