A protocol for two-party secure function evaluation (2P-SFE) aims to allow the parties to learn the output of function f of their private inputs, while leaking nothing more. In a sense, such a protocol realizes a trusted oracle that computes f and returns the result to both parties. There have been tremendous strides in efficiency over the past ten years, yet 2P-SFE protocols remain impractical for most real-time, online computations, particularly on modestly provisioned devices. Intel's Software Guard Extensions (SGX) provides hardware-protected execution environments, called enclaves, that may be viewed as trusted computation oracles. While SGX provides native CPU speed for secure computation, previous side-channel and micro-architecture attacks have demonstrated how security guarantees of enclaves can be compromised. In this paper, we explore a balanced approach to 2P-SFE on SGX-enabled processors by constructing a protocol for evaluating f relative to a partitioning of f. This approach alleviates the burden of trust on the enclave by allowing the protocol designer to choose which components should be evaluated within the enclave, and which via standard cryptographic techniques. We describe SGX-enabled SFE protocols (modeling the enclave as an oracle), and formalize the strongest-possible notion of 2P-SFE for our setting. We prove our protocol meets this notion when properly realized. We implement the protocol and apply it to two practical problems: privacy-preserving queries to a database, and a version of Dijkstra's algorithm for privacy-preserving navigation. Our evaluation shows that our SGX-enabled SFE scheme enjoys a 38x increase in performance over garbled-circuit-based SFE. Finally, we justify modeling of the enclave as an oracle by implementing protections against known side-channels.
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This content will become publicly available on July 1, 2024
An Extensible Orchestration and Protection Framework for Confidential Cloud Computing
Confidential computing solutions are crucial to address the cloud privacy concerns. Although SGX has witnessed significant adoption in the cloud, the reliance on hardware implementation is restrictive for cloud providers in terms of orchestrating deployments and providing stronger security to their clients’ enclaves. eOPF addresses this limitation by providing a comprehensive, secure hypervisor-level instrumentation framework with the ability to monitor all enclave-OS interactions and implement protected services. eOPF overcomes several challenges including bridging the semantic gap between the hypervisor and SGX and attesting the co-location of the framework with enclaves. Using eOPF, we implement two protected services that provide platform resource orchestration and complementary enclave side-channel defense. Our evaluation shows that eOPF incurs very low performance overhead (<2%) in its default state and only a modest overhead (geometric mean of 17% on SPEC) when strong, complementary side-channel defenses are enabled, making eOPF an efficient and practical solution for the cloud.
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- Award ID(s):
- 2145888
- NSF-PAR ID:
- 10480228
- Publisher / Repository:
- USENIX Association
- Date Published:
- Journal Name:
- 17th USENIX Symposium on Operating Systems Design and Implementation (OSDI 23)
- Format(s):
- Medium: X
- Location:
- Boston, MA
- Sponsoring Org:
- National Science Foundation
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