HDLBC: A lightweight block cipher with high diffusion

Abstract

Both the diffusion property and the area consumption are two important evaluation criteria in the design and implementation of symmetric encryption algorithms. Many AND-Rotation-XOR (AND-RX) block ciphers are usually designed by reducing the diffusion property to minimize the area consumption. On the other hand, these AND-RX block ciphers use multiple round function operations to achieve the enough diffusion property, which always induce more area consumption in their hardware implementation. How to trade off the diffusion property and the area consumption appears to be an interesting task in the design of block cipher. In this paper, HDLBC as a new family of lightweight block cipher (with 64-bit plaintext and 64-bit/128-bit key) for the Internet of Things (IoT) is proposed. More specifically, the HDLBC is designed by using only two F-functions (RA1 and RA2), where the non-linear layer of the F-functions is constructed by the NAND operation that consumes the least area among the non-linear logic operations. To the best of our knowledge, HDLBC cipher requires the minimum number of F-functions to provide the diffusion property, where the F-functions require fewer implementation resources than the F-functions of existing similar encryption algorithms. It illustrates the hardware implementation of HDLBC cipher on SMIC 0.18μm requires only 1248 Gate Equivalents (GEs), its throughput rate is 256 Kbps at 100 KHz. Compared with other encryption algorithms, the implementation performance of HDLBC cipher achieves well-balanced in both the area consumption and diffusion property. Moreover, the security analysis shows that HDLBC cipher has enough security margin against various known attacks, such as differential cryptanalysis, linear cryptanalysis, impossible differential cryptanalysis, zero correlation cryptanalysis, etc.