A lightweight block encryption algorithm for narrowband internet of things

Abstract

Aiming at the security of terminal data information in the application architecture of narrowband internet of things (NB-IOT), this paper proposes a lightweight block encryption algorithm SPNRX based on variant ARX (And-Rotate-XOR) structure and Substitute Permutation Network (SPN) structure. The proposed algorithm takes into account the unique security requirements of the NB-IOT terminal, such as simplifying the encryption process as far as possible, not too long encrypted data and high security level, and reduces the number of encryption rounds. It overcomes the shortcoming that half of the block information of ARX structure does not change during one round of encryption, so as to improve the diffusion speed. In addition, considering the security of keys and the cost of hardware implementation, a key schedule based on matrix transformation and P-box permutation is proposed. Through the security analysis of SPNRX algorithm, the analysis shows that SPNRX algorithm has resistance to differential analysis, linear analysis and so on. Finally, the hardware and software performance of SPNRX algorithm is tested. The experimental results show that the hardware implementation cost of the proposed algorithm is low, only 1093 GE based on 0.13 micron ASIC process is required. And the software implementation of the proposed algorithm performs well. The encryption and decryption of the proposed algorithm on the 64-bit processor takes about 0.763 milliseconds and 0.772 milliseconds. And it requires 41.06MB of memory resources. In addition, the security strength and encryption effect of the algorithm are tested through key sensitivity, information entropy, etc. The results show that the proposed algorithm has high enough security.