Design and implementation of an advanced substitution-permutation encryption network

To solve the problems of data security in modern electronic communication environments and applications, researchers have been placing much effort on the design of efficient and secure ciphers. Substitution-permutation encryption networks (SPNs) are an important class of private-key block ciphers. The objective of this thesis is to develop an advanced substitution-permutation encryption network that not only is efficiently secure but also can be simply implemented in both hardware and software.;Finally, we implement an SPN which consists of our new linear transformation and 4 x 4 S-boxes satisfying our new design criterion by using a Field Programmable Gate Array (FPGA). The simulation results confirm that the digital hardware implementation of the SPN is practical and not complicated.;Two of the most powerful attacks are linear cryptanalysis and differential cryptanalysis. After investigating the application of linear cryptanalysis to an SPN, a new nonlinearity criterion for the design of S-boxes is presented. S-boxes satisfying this criterion strengthen the ability of an SPN to frustrate linear cryptanalysis. As well, we propose a novel linear transformation as the method of interconnection between rounds of S-boxes. The use of the linear transformation increases the resistance of an SPN to both linear cryptanalysis and differential cryptanalysis.