Efficient Control Flow Attestation by Speculating on Control Flow Path Representations

TL;DR

This paper introduces RESPEC-CFA, an architectural extension for control flow attestation that significantly reduces log sizes by speculating on control flow locality and encoding, enhancing practicality.

Contribution

RESPEC-CFA is a novel extension that enables speculation on control flow locality and Huffman encoding, drastically reducing control flow log sizes for more practical CFA.

Findings

CFlog sizes reduced by up to 90.1% with RESPEC-CFA.

Combined with prior methods, reductions reach up to 99.7%.

RESPEC-CFA advances practical control flow attestation.

Abstract

Control Flow Attestation (CFA) allows remote verification of run-time software integrity in embedded systems. However, CFA is limited by the storage/transmission costs of generated control flow logs (CFlog). Recent work has proposed application-specific optimizations by speculating on likely sub-paths in CFlog and replacing them with reserved symbols at runtime. Albeit effective, prior approaches do not consider the representation of addresses in a control flow path for speculation. This work proposes RESPEC-CFA, an architectural extension for CFA allowing for speculation on (1) the locality of control flows and (2) their Huffman encoding. Alone, RESPEC-CFA reduces CFlog sizes by up to 90.1%. Combined with prior methods, RESPEC-CFA yields reductions of up to 99.7%, representing a significant step toward practical CFA.