A Flexible Gimli Hardware Implementation in FPGA and Its Application to RFID Authentication Protocols

Radio Frequency Identification (RFID) systems have bestowed numerous conveniences in a multitude of applications, but the underlying wireless communications architecture makes it vulnerable to several security threats. To mitigate these issues, various authentication protocols have been proposed. The literature accommodates comprehensive proposals and analysis of authentication protocols, but not many of them provide hardware implementations. In addition, there is diverse demand for hardware area and throughput (TP) requirements from RFID system components (tags, readers, database servers), which demand a flexible implementation strategy. This paper proposes a flexible implementation strategy for the lightweight authenticated encryption (AE) and hash function called Gimli, and applies it to a state-of-the-art authentication protocol. This allows the authentication protocol to be implemented efficiently, wherein the area and TP can be adjusted flexibly according to the RFID system requirements. This implementation strategy is generic; it can be used to implement any other AE and hash functions. This strategy can also be applied to other authentication protocols that heavily use AE and hash functions. To provide a detailed analysis, the hardware optimization techniques in each component of the RFID system for a state-of-the-art authentication protocol are analyzed. When implemented with the most area-optimized versions, we achieve TP of 740 Mbps and 420 Mbps for Gimli hash and Gimli AE, respectively, and for throughput-oriented implementation, the results are 3.08 Gbps and 1.43 Gbps, respectively. This shows that the proposed implementation strategies allow us to implement authentication protocols in a flexible manner to meet the differing requirements in TP and area for RFID applications.