Designing a secure cryptographic accelerator is challenging as vulnerabilities may arise from design decisions and implementation flaws. To provide high security assurance, we propose to design and build cryptographic accelerators with hardware-level information flow control so that the security of an implementation can be formally verified. This paper uses an AES accelerator as a case study to demonstrate how to express security requirements of a cryptographic accelerator as information flow policies for security enforcement. Our AES prototype on an FPGA shows that the proposed protection has a marginal impact on area and performance.

Specialized hardware accelerators are being increasingly integrated into today's computer systems to achieve improved performance and energy efficiency. However, the resulting variety and complexity make it challenging to ensure the security of these accelerators. To mitigate complexity while guaranteeing security, we propose a high-level synthesis (HLS) infrastructure that incorporates static information flow analysis to enforce security policies on HLS-generated hardware accelerators. Our security-constrained HLS infrastructure is able to effectively identify both explicit and implicit information leakage. By detecting the security vulnerabilities at the behavioral level, our tool allows designers to address these vulnerabilities at an early stage of the design flow. We further propose a novel synthesis technique in HLS to eliminate timing channels in the generated accelerator. Our approach is able to remove timing channels in a verifiable manner while incurring lower performance overhead for high-security tasks on the accelerator.

In the last decade, progress in logic synthesis has brought about new advantageous circuit representations. These representations, such as And-Inverter Graphs in the ubiquitous open-source synthesizer ABC, have inspired new designs of Field Programmable Gate Arrays (FPGAs), which, instead of using Look-Up Tables (LUTs), mimic the topology of the circuit representation in the basic logic cells. More recent examples are Majority-Inverter Graphs, another uniform representation which has triggered considerable interest in synthesis and which naturally suggests new logic cells. Yet, in this paper we observe how naïvely adapting technology mapping solutions for classic LUT-based FPGAs to these new architectures incurs severe shortcomings. The key issue is that LUTs are inherently input-constrained (the logic function they implement is irrelevant) and have generally a single output; on the other hand, logic cells made of uniform networks of some fundamental logic function (e.g., And-Invert) are constrained in terms of logic depth and multiple outputs are an integral feature. We introduce novel and effective solutions to address these differences; the result is a highly versatile mapper—thus enabling further research in these new architectures—with a significantly better performance than what is described in literature for one such architecture. Specifically, when we compare with the state of the art on one sample architecture, we obtain a significant decrease in area (on average 18% over several benchmarks) while also improving slightly the critical path (a reduction of 3%).

Dual-output lookup tables (LUTs) are mainstream in the design of commercial FPGA products. A detailed exploration of architectural parameters of FPGAs based on dualoutput LUTs is presented. Different from traditional single-output LUT based architecture, “shared inputs” between the sub-LUTs is a new parameter specific to dual-output architecture. In this paper, we focus on the effect of ratio of shared inputs on the performance and area-efficiency. First, we study the required cluster inputs and derive a relationship between cluster inputs, LUT size and cluster size under different ratios of shared inputs. Secondly, our evaluation results show that a FPGA with 4-LUTs and a shared input ratio of two thirds is preferred for area-efficiency, while a large LUT size of 9 with no shared inputs achieves best performance. Finally, we determine that a LUT size of 4, a cluster size from 3 to 8, and a shared input ratio between 1/3 and 2/3, provide the best area-delay product for dual-output LUT based FPGAs.