加速对称密码编码的快速S盒代换指令及其硬件实现

Fast S-Box Substitution Instructions and Their Hardware Implementation Scheme Accelerating Symmetric Cryptographic Processing

S盒代换是大多数对称密码算法的核心操作,加快S盒代换是提高密码编码处理速度的关键。本文采用专用指令扩展的方法支持快速S盒代换,构造了一种灵活的并行S盒单元,设计了S盒代换指令。并行S盒单元由多路查找表和一个后处理模块组成,它作为功能部件集成到Leon2处理器片上。在Virtex-Ⅱ XC2V3000 FPGA上的综合结果表明,扩展后的处理器中并行S盒单元仅使用了1KB的存储和少量的逻辑资源。依据Amdahl定律评估了S盒代换指令的效率,对AES算法可以取得两倍以上的总体加速,对使用S盒操作的其他对称密码预计也能得到显著加速。

In popular symmetric ciphers, the S-box substitution is the core operation that dominates the execution of cryptographic algorithms. In this paper, a method of application-specific instruction-set extension is used for accelerating this key operation in symmetric cryptography. By constructing a novel flexible on-chip parallel substitution box unit consisting of multiple lookup tables and a post-processing module, two instructions for the S-box access are designed and integrated into the 32-bit Leon2 processor. Implementing the extended processor core on Virtex-Ⅱ XC2V3000 FPGA shows that the parallel substitution box unit uses only 1KB of memory and a small amount of logic circuits. Evaluation of the efficiency of the S-box access instructions for AES is conducted according to the Amdahl Law, and the results show that the overall speedup greater than 2 can be achieved. Benefits for other symmetric ciphers using the S-box substitution as their core operation are accordingly expected.