Architectures and FPGA implementations of the 64-bit MISTY1 block cipher

In this paper, we present two alternative architectures and FPGA implementations of the 64-bit NESSIE proposal, MISTY1 block cipher. The first architecture is suitable for applications with high-performance requirements. A throughput of up to 12.6 Gbps can be achieved at a clock frequency of 168 MHz. The main characteristic of this architecture is that uses RAM blocks embedded in modern FPGA devices in order to implement the S-boxes defined in the block cipher algorithm. The second architecture can be used in implementing applications on area-constrained systems. It utilizes feedback logic and inner pipeline with negative edge-triggered register. This technique shortens the critical path, without increasing the latency of the MISTY1 algorithm execution. Compared with an implementation without inner pipeline, performance improvement of 97% is achieved. The measured throughput of the second architecture implementation is 561 Mbps at 79 MHz.