Biblio

Field-Programmable Gate Arrays (FPGAs) are versatile, reconfigurable integrated circuits that can be used as hardware accelerators to process highly-sensitive data. Leaking this data and associated cryptographic keys, however, can undermine a system's security. To prevent potentially unintentional interactions that could break separation of privilege between different data center tenants, FPGAs in cloud environments are currently dedicated on a per-user basis. Nevertheless, while the FPGAs themselves are not shared among different users, other parts of the data center infrastructure are. This paper specifically shows for the first time that powering FPGAs, CPUs, and GPUs through the same power supply unit (PSU) can be exploited in FPGA-to-FPGA, CPU-to-FPGA, and GPU-to-FPGA covert channels between independent boards. These covert channels can operate remotely, without the need for physical access to, or modifications of, the boards. To demonstrate the attacks, this paper uses a novel combination of "sensing" and "stressing" ring oscillators as receivers on the sink FPGA. Further, ring oscillators are used as transmitters on the source FPGA. The transmitting and receiving circuits are used to determine the presence of the leakage on off-the-shelf Xilinx boards containing Artix 7 and Kintex 7 FPGA chips. Experiments are conducted with PSUs by two vendors, as well as CPUs and GPUs of different generations. Moreover, different sizes and types of ring oscillators are also tested. In addition, this work discusses potential countermeasures to mitigate the impact of the cross-board leakage. The results of this paper highlight the dangers of shared power supply units in local and cloud FPGAs, and therefore a fundamental need to re-think FPGA security for shared infrastructures.

Security concerns for field-programmable gate array (FPGA) applications and hardware are evolving as FPGA designs grow in complexity, involve sophisticated intellectual properties (IPs), and pass through more entities in the design and implementation flow. FPGAs are now routinely found integrated into system-on-chip (SoC) platforms, cloud-based shared computing resources, and in commercial and government systems. The IPs included in FPGAs are sourced from multiple origins and passed through numerous entities (such as design house, system integrator, and users) through the lifecycle. This paper thoroughly examines the interaction of these entities from the perspective of the bitstream file responsible for the actual hardware configuration of the FPGA. Five stages of the bitstream lifecycle are introduced to analyze this interaction: 1) bitstream-generation, 2) bitstream-at-rest, 3) bitstream-loading, 4) bitstream-running, and 5) bitstream-end-of-life. Potential threats and vulnerabilities are discussed at each stage, and both vendor-offered and academic countermeasures are highlighted for a robust and comprehensive security assurance.

The imbalance relationship between FPGA hardware/software providers and FPGA users challenges the assurance of secure design on FPGAs. Existing efforts on FPGA security primarily focus on reverse engineering the downloaded FPGA configuration, retrieving the authentication code or crypto key stored on the embedded memory in FPGAs, and countermeasures for the security threats above. In this work, we investigate new security threats from malicious FPGA tools, and identify stealthy attacks that could occur during FPGA deployment. To address those attacks, we exploit the principles of moving target defense (MTD) and propose a FPGA-oriented MTD (FOMTD) method. Our method is composed of three defense lines, which are formed by an improved user constraint file, random selection of design replicas, and runtime submodule assembling, respectively. The FPGA emulation results show that the proposed FOMTD method reduces the hardware Trojan hit rate by 60% over the baseline, at the cost of 10.76% more power consumption.