Pipelined Implementation of Dynamic Rijndael S-Box

architecture for S-Box is proposed in this paper. ROM based look-up table implementation of S-Box requires more memory and introduce unbreakable delay for its access. Pipelined S-Box of combinational logic based implementation gives higher throughput and less delay as compared to that of no pipelined S-Box. 5, 6 and 7 stages of pipelined architecture has been simulated using Xilinx 9.2i for SPARTAN-3 FPGA. The result from Place and Route reports shows increase in maximum clock frequency at the cost of increased number of used slices. However the total delay calculated for the SubByte substitution for large amount of data is reduced considerably. KeywordsAES, S-Box.