High‐throughput and flexible ASIC implementations of SIMON and SPECK lightweight block ciphers

Abstract

SummaryIn this paper, high‐throughput and flexible hardware implementations of the SIMON and SPECK lightweight block ciphers are presented. The most complex block in the SPECK algorithm is addition modulo 2n, where n is word size (half of the input data). In the proposed structure of modular adder, we used the Sklansky adder, which is an efficient parallel prefix adder with low critical path delay and suitable hardware resources. In the SIMON block cipher, to reduce critical path delay, we use a tree structure for implementation of XOR operations. In addition, we proposed flexible structures that can perform various configurations of the SIMON and SPECK ciphers to support variable key sizes (128, 144, 192, and 256 bits) and block sizes (64, 96, and 128 bits). Therefore, the flexible architectures provide versatile implementations with adaptive security level and the ability of encryption of longer messages based on variable key size and variable block size. Implementation results of the proposed structures in 180 nm CMOS technology for different key and block sizes are achieved. The results show that the proposed structures have better critical path delay compared with other's related works.