The paper entitled “ZEKRO: Zero-Knowledge Proof of Integrity Conformance” was accepted for presentation at the 2022 International Conference on Availability, Reliability, and Security (ARES), which was held on August 23-26, 2022, in Vienna and subsequently appeared in the International Conference Proceedings Series published by ACM ICPS available here: https://dl.acm.org/doi/abs/10.1145/3538969.3539004.
In this work, RAINBOW partners propose a general ZEro-Knowledge pRoof of cOnformance (ZEKRO) scheme, which considers mutually distrusting participants and enables a prover to convince an untrusted verifier about the correctness of its state in zero knowledge, i.e., without revealing anything about its state, by ensuring that the prover cannot cheat. In particular, ZEKRO uses trusted computing abstractions to overcome the barriers of configuration privacy and scalability. These abstractions provide another building block for constructing scalable services that seamlessly mix in multi-domain environments and are more resilient to integrity concerns.
The proposed design includes two crucial main innovations to overcome the limitations of existing TPM-based privacy-respecting remote attestation protocols. First, the ZEKRO scheme provides the trusted computing abstraction, called policy-restricted attestation key, that restricts a node’s attestation key (secured in its TPM) to policies chosen by an authorizing entity (e.g., a domain orchestrator) and ensures that the node can only use the key to sign challenges if its configuration satisfies a policy. Second, to control which of the already authorized policies a node can satisfy during attestation, we propose creating policies that additionally require explicit, time-limited authorization, called leases, to be satisfiable, which allows an authorizing entity to control which policy can temporarily be satisfied.