HermiCache: Enclave-Aware Cache Replacement for Trusted Execution Environments
Colloque National GDR SoC2 — 2026
Trusted Execution Environments (TEEs) protect enclave memory from untrusted software but remain vulnerable to cache-based side-channel attacks due to shared microarchitectural resources. Existing hardware defenses mainly rely on cache partitioning, which reduces effective capacity, or randomized remapping, which provides only probabilistic protection. This paper presents HermiCache, a deterministic enclave-aware cache isolation mechanism that enforces eviction confinement through ownership-aware replacement without partitioning. Each cache line is extended with lightweight metadata so that lookup and replacement decisions are restricted to the requester security domain. HermiCache is implemented at RTL in the CVA6 RISC-V core and integrated with Keystone. FPGA synthesis shows less than 5% hardware overhead, while gem5 evaluation reports up to 5% IPC degradation for secure and non-secure workloads.