Since cryptographic protocols do not compose well, especially when run concurrently, SGX remote attestation is only a necessary pre-condition for securely instantiating an enclave. In practice, one needs to analyze all the different interacting enclaves as a \textit{single protocol} and make sure that no sub-computation of the protocol can be simulated outside of the enclave. In this paper we describe protocol design problems under (a) sequential-composition, (b) concurrent-composition, and (c) enclave state malleability that must be taken into account while designing new enclaves. We analyze Intel provided EPID \textsf{Provisioning} and \textsf{Quoting} enclave and report our (largely positive) findings. We also provide details about how SGX uses EPID Group Signatures and report (largely negative) results about claimed anonymity guarantees.
Category / Keywords: applications / Original Publication (with minor differences): BlackHat'17 Date: received 30 Jul 2017 Contact author: yogesh swami at gmail com Available format(s): PDF | BibTeX Citation Version: 20170801:152136 (All versions of this report) Short URL: ia.cr/2017/736