Abstract
S-box is a core component of many block cipher algorithms. A reconfigurable S-box based on look-up table (LUT) with memory-sharing is proposed in this paper. It uses a sharing memory to support different S-box operation modes (4 × 4, 6 × 4, and 8 × 8) for most of the block cipher algorithms as well as reduce memory size. It also supports high-speed pipeline structure of DES and Serpent. This new type of S-box is applied in a reconfigurable cryptographic coprocessor under 0.18μm CMOS process. It is also used in a DES circuit with 16 pipeline stages. Synthesis results show that it works at 100MHz frequency with flexibility of different modes and a reduced area compared to non-memory-sharing LUT method with equivalent sizes of different S-boxes.
