Design and cryptanalysis of stream and block ciphers

This work contains a general introduction to cryptography science with a focus on block and stream ciphers. We describe their most famous structures and the building blocks that can be involved. Moreover, we study the relationship between the chaotic theory and the cryptography system. Furthermore, we present the most general type of cryptanalysis techniques. We evaluate several cryptosystems in the context of multimedia data which shows the weaknesses of standards encryption algorithm named Advanced Encryption Standard (AES). This work contributes to the field of cryptanalysis by examining block and stream schemes. Moreover, it contributes in the field also of cryptography by designing new cryptosystems dedicated to multimedia data especially images by adopting a new structure named outer-inner structure. The later mixes the advantage of a classic and chaos-based cipher. This cipher is designed in a way to achieve high diffusion and confusion properties and to make the differential and linear cryptanalysis unfeasible. Moreover, in this work, we present a new cipher adoptable for real-time applications based on a chaos system.