Biblio

Field Programmable Gate Arrays (FPGAs) are being increasingly deployed in diverse applications including the emerging Internet of Things (IoT), biomedical, and automotive systems. However, security of the FPGA configuration file (i.e. bitstream), especially during in-field reconfiguration, as well as effective safeguards against unauthorized tampering and piracy during operation, are notably lacking. The current practice of bitstreram encryption is only available in high-end FPGAs, incurs unacceptably high overhead for area/energy-constrained devices, and is susceptible to side channel attacks. In this paper, we present a fundamentally different and novel approach to FPGA security that can protect against all major attacks on FPGA, namely, unauthorized in-field reprogramming, piracy of FPGA intellectual property (IP) blocks, and targeted malicious modification of the bitstream. Our approach employs the security through diversity principle to FPGA, which is often used in the software domain. We make each device architecturally different from the others using both physical (static) and logical (time-varying) configuration keys, ensuring that attackers cannot use a priori knowledge about one device to mount an attack on another. It therefore mitigates the economic motivation for attackers to reverse engineering the bitstream and IP. The approach is compatible with modern remote upgrade techniques, and requires only small modifications to existing FPGA tool flows, making it an attractive addition to the FPGA security suite. Our experimental results show that the proposed approach achieves provably high security against tampering and piracy with worst-case 14% latency overhead and 13% area overhead.

The trend in computing is towards the use of FPGAs to improve performance at reduced costs. An indication of this is the adoption of FPGAs for data centre and server application acceleration by notable technological giants like Microsoft, Amazon, and Baidu. The continued protection of Intellectual Properties (IPs) on the FPGA has thus become both more important and challenging. To facilitate IP security, FPGA vendors have provided bitstream authentication and encryption. However, advancements in FPGA programming technology have engendered a bitstream manipulation technique like partial bitstream relocation (PBR), which is promising in terms of reducing bitstream storage cost and facilitating adaptability. Meanwhile, encrypted bitstreams are not amenable to PBR. In this paper, we present three methods for performing encrypted PBR with varying overheads of resources and time. These methods ensure that PBR can be applied to bitstreams without losing the protection of IPs.