Securing firmware updates using Transparency and Traceability services

Firmware update mechanisms are a critical part of the software supply chain in IoT and embedded systems, yet they remain vulnerable to a range of attacks-particularly those targeting the signing keys of firmware authors. A compromised signing key can be used to distribute malicious firmware that appears legitimate, undermining the integrity of the entire update process. In this paper, we address this class of attacks by introducing transparency and traceability services into the firmware update pipeline. We propose the use of a transparency registry-an immutable, append-only log where all firmware signing events are recorded. By monitoring this registry, key compromise and unauthorized signing activity can be detected and mitigated. Our approach shifts trust from opaque signature validation to verifiable, auditable records of signing activity. To evaluate this approach, we design and implement two systems: one based on a centralized transparency registry built using Merkle tree structures, and another based on a decentralized, permissioned blockchain. Both implementations demonstrate that transparency-based defenses against firmware supply chain attacks are practical, scalable, and effective.