RepCloud: achieving fine-grained cloud TCB attestation with reputation systems

Abstract

Security concerns for emerging cloud computing models have become the focus of much research, but little of this targets the underlying infrastructure. Trusted Cloud proposals generally assert that the Trusted Computing Base (TCB) of the cloud should be clearly defined and attested to. However, specific characteristics of trust in the cloud make such solutions difficult to implement in an effective and practical way. We present RepCloud, a reputation system for managing decentralised attestation metrics in the cloud. We observe that as being deterministic and tamper-proof, trust evidence generated by the TCG framework can be efficiently transmitted within the cloud. In a web of nodes with high connectivity and mutual-attestation frequency, corrupted nodes can be identified effectively. By modelling this web with RepCloud, we achieved a fine-grained cloud TCB attestation scheme with high confidence for trust. Cloud users can determine the security properties of the exact nodes that may affect the genuine functionalities of their applications, without obtaining much internal information of the cloud. Experiments showed that besides achieved fine-grained attestation RepCloud still incurred lower trust management overhead than existing trusted cloud proposals.