The Costs of Confidentiality in Virtualized FPGAs

Some modern datacenters are augmenting their compute infrastructure by deploying field-programmable gate arrays (FPGAs) to provide users with specialized accelerators that offer superior compute capability, increased energy efficiency, lower latency, and more programming flexibility than CPUs. However, the higher programming flexibility of FPGAs also gives more capabilities to malicious users to remotely sniff data from other applications running on the same FPGA. This has created a challenge for efficient utilization of FPGAs in datacenters: FPGAs in datacenters are currently not shared between users due to potential security risks. In this paper, we propose different techniques to defeat data-sniffing attacks in datacenter FPGAs by encrypting/decrypting the user application’s data. We describe techniques that are appropriate to different trust levels and rigorously evaluate the costs of these data confidentiality techniques in current virtualized FPGAs. In addition, for each trust level, we propose an architectural change to the FPGA to mitigate the costs of providing data confidentiality. We also investigate the role of interconnect in these architectural changes and demonstrate that more efficient security features can be implemented together with the interconnect if the FPGAs use a hard network on chip.