KingsGuard: Enclave Data Protection Under Real-World TEE Vulnerabilities

2026-05-01

AI Summary

This work addresses the vulnerability of Trusted Execution Environments (TEEs) to sensitive data leakage stemming from enclave code flaws and hardware-level exploits, which undermines their resilience against real-world threats. To bridge the gap between idealized TEE security models and practical robustness, the authors propose a RISC-V-based hardware-enhanced architecture that enables fine-grained tracking of sensitive data flows and enforces boundary-aware access control directly at the hardware level. Notably, the design incorporates, for the first time, a controlled declassification mechanism that systematically monitors intra-enclave data propagation and securely releases information when appropriate. FPGA-based prototype evaluation demonstrates that the proposed solution incurs only a 10.8% area overhead and a 5.69% performance penalty while effectively preventing unauthorized data exfiltration.

Abstract

Trusted Execution Environments (TEEs) have emerged as a cornerstone for securing sensitive computations by providing isolated enclaves protected from untrusted software. However, their security guarantees are undermined by vulnerabilities in both the enclave code and the underlying hardware design, which can allow sensitive data to leak despite strong isolation guarantees. This paper presents KINGSGUARD, a novel TEE design that systematically monitors and controls the propagation of sensitive data within an enclave. By enforcing fine-grained data flow tracking and checks in hardware, our approach ensures that sensitive data does not leave the enclave boundary, thus bridging the gap between the idealized threat models of TEEs and their practical realizations. Additionally, to balance security with practical functionality, we introduce controlled declassification at enclave boundaries, allowing intentional release of data to the outside world. Our implementation of KINGSGUARD on a RISC-V processor has a 10.8% hardware area overhead when synthesized on FPGA and a 5.69% performance overhead.

Problem

• Trusted Execution Environments
• enclave
• data leakage
• hardware vulnerabilities
• security guarantees

Innovation

• Trusted Execution Environment
• Data Flow Tracking
• Hardware-enforced Security
• Controlled Declassification
• Enclave Protection