Cloud providers have widely adopted FPGAs to meet the high-performance, energy-efficient demands of cloud workloads. While they offer homogeneous FPGAs per service, recent FPGA products exhibit increasing heterogeneity in terms of vendors, capacity, off-chip memory, and performance. These diverse properties not only render applications incompatible across different FPGAs but also lead to performance disparities and resource inefficiency.

We introduce TNIC, a trusted NIC architecture for building trustworthy distributed systems deployed in heterogeneous, untrusted (Byzantine) cloud environments. TNIC builds a minimal, formally verified, silicon root-of-trust at the network interface level. We strive for three primary design goals: (1) a host CPU-agnostic unified security architecture by providing trustworthy network-level isolation; (2) a minimalistic and verifiable TCB based on a silicon root-of-trust by providing two core properties of transferable authentication and non-equivocation; and (3) a hardware-accelerated trustworthy network stack leveraging SmartNICs. Based on the TNIC architecture and associated network stack, we present a generic set of programming APIs and a recipe for building high-performance, trustworthy, distributed systems for Byzantine settings. We formally verify the safety and security properties of our TNIC while demonstrating its use by building four trustworthy distributed systems. Our evaluation of TNIC shows up to 6× performance improvement compared to CPU-centric TEE systems.