Biblio

The Internet of Things integrates multiple hardware appliances from large cloud data centres to constrained devices embedded within the physical reality, from multiple vendors and providers, under the same infrastructure. These appliances are subject to different restrictions, have different available resources and show different risk profiles and vulnerabilities. In these scenarios, remote attestation mechanisms are essential, enabling the verification of a distant appliance’s internal state before allowing it to access sensitive data or execute critical workloads. This work proposes a new attestation approach based on a Trusted Platform Module (TPM), devoted to performing Remote Attestation as a Service (RAaaS) while guaranteeing essential properties such as flexibility, generality, domain separation and authorized initiation. The proposed solution can prove both edge devices and IoT devices reliability to services running on cloud data centres. Furthermore, the first prototype of this service has been validated and evaluated via a real use case.

For a computing platform that is compliant with the Trusted Platform Module (TPM) standard, direct anonymous attestation (DAA) is an appropriate cryptographic protocol for realizing an anonymous subscription system. This approach takes advantage of a cryptographic key that is securely embedded in the platform's hardware, and enables privacy-preserving authentication of the platform. In all of the existing DAA schemes, the platform suffers from significant computational and communication costs that increase proportionally to the size of the revocation list. This drawback renders the existing schemes to be impractical when the size of the revocation list grows beyond a relatively modest size. In this paper, we propose a novel scheme called Lightweight Anonymous Subscription with Efficient Revocation (LASER) that addresses this very problem. In LASER, the computational and communication costs of the platform's signature are multiple orders of magnitude lower than the prior art. LASER achieves this significant performance improvement by shifting most of the computational and communication costs from the DAA's online procedure (i.e., signature generation) to its offline procedure (i.e., acquisition of keys/credentials). We have conducted a thorough analysis of LASER's performance related features. We have implemented LASER on a laptop with an on-board TPM. To the best of our knowledge, this is the first implementation of a DAA scheme on an actual TPM cryptoprocessor that is compliant with the most recent TPM specification, viz., TPM 2.0.

Most security software tools try to detect malicious components by cryptographic hashes, signatures or based on their behavior. The former, is a widely adopted approach based on Integrity Measurement Architecture (IMA) enabling appraisal and attestation of system components. The latter, however, may induce a very long time until misbehavior of a component leads to a successful detection. Another approach is a Dynamic Runtime Attestation (DRA) based on the comparison of binary code loaded in the memory and well-known references. Since DRA is a complex approach, involving multiple related components and often complex attestation strategies, a flexible and extensible architecture is needed. In a cooperation project an architecture was designed and a Proof of Concept (PoC) successfully developed and evaluated. To achieve needed flexibility and extensibility, the implementation facilitates central components providing attestation strategies (guidelines). These guidelines define and implement the necessary steps for all relevant attestation operations, i.e. measurement, reference generation and verification.

This paper has presented an approach of vTPM (virtual Trusted Platform Module) Dynamic Trust Extension (DTE) to satisfy the requirements of frequent migrations. With DTE, vTPM is a delegation of the capability of signing attestation data from the underlying pTPM (physical TPM), with one valid time token issued by an Authentication Server (AS). DTE maintains a strong association between vTPM and its underlying pTPM, and has clear distinguishability between vTPM and pTPM because of the different security strength of the two types of TPM. In DTE, there is no need for vTPM to re-acquire Identity Key (IK) certificate(s) after migration, and pTPM can have a trust revocation in real time. Furthermore, DTE can provide forward security. Seen from the performance measurements of its prototype, DTE is feasible.