FORTRESS: FORtified Tamper-Resistant Envelope with Embedded Security Sensor

Protecting security modules from attacks on the hardware level presents a very challenging endeavor since the attacker can manipulate the device directly through physical access. To address this issue, different physical security enclosures have been developed with the goal to cover entire hardware modules and, hence, protect them from external manipulation. Novel concepts are battery-less and based on Physical Unclonable Functions (PUFs), aiming at overcoming the most severe drawbacks of past devices; the need for active monitoring and, thus, limited battery life-time. Although some progress has already been made for certain aspects of PUF-based enclosures, the combination and integration of all required components and the creation of a corresponding architecture for Hardware Security Modules (HSMs) is still an open issue. In this paper, we present FORTRESS, a PUF-based HSM that integrates the tamper-sensitive capacitive PUF-based envelope and its embedded security sensor IC into a secure architecture. Our concept proposes a secure life cycle concept including shipment aspects, a full key generation scheme with re-enrollment capabilities, and our the next generation Embedded Key Management System. With FORTRESS, we take the next step towards the productive operation of PUF-based HSMs.