A Lightweight Stream Cipher WG-7 for RFID Encryption and Authentication

The family of WG stream ciphers has good randomness properties. In this paper, we parameterize WG-7 stream cipher for RFID tags, where the modest computation/storage capabilities and the necessity to keep their prices low present a challenging problem that goes beyond the well-studied cryptography. The rigorous security analysis of WG-7 indicates that it is secure against time/memory/data trade off attack, differential attack, algebraic attack, correlation attack and Discrete Fourier Transform (DFT) attack. Furthermore, we offer efficient implementation of WG-7 on the 4-bit microcontroller ATAM893-D and the 8-bit microcontroller ATmega8 from ATmel. The experimental results show that WG-7 outperforms most of previous proposals in terms of throughput and implementation complexity. Moreover, we propose a mutual authentication protocol based on WG-7, which provides the untraceability, resistance of tag impersonation and reader impersonation. With its verified cryptographic properties, low implementation complexity and ideal throughput, WG-7 is a promising candidate for RFID applications.