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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. 

Confidential virtual machines (CVMs) enabled by AMD SEV provide a protected environment for sensitive computations on an untrusted cloud. Unfortunately, CVMs are typically deployed with huge and vulnerable operating system kernels, exposing the CVMs to attacks that exploit kernel vulnerabilities. Veil is a versatile CVM framework that efficiently protects critical system services like shielding sensitive programs, which cannot be entrusted to the buggy kernel. Veil leverages a new hardware primitive, virtual machine privilege levels (VMPL), to install a privileged security monitor inside the CVM. We overcome several challenges in designing Veil, including (a) creating unlimited secure domains with a limited number of VMPLs, (b) establishing resource-efficient domain switches, and (c) maintaining commodity kernel backwards-compatibility with only minor changes. Our evaluation shows that Veil incurs no discernible performance slowdown during normal CVM execution while incurring a modest overhead (2 − 64%) when running its protected services across real-world use cases. 

Abstract The Bitcoin network has offered a new way of securely performing financial transactions over the insecure network. Nevertheless, this ability comes with the cost of storing a large (distributed) ledger, which has become unsuitable for personal devices of any kind. Although the simplified payment verification (SPV) clients can address this storage issue, a Bitcoin SPV client has to rely on other Bitcoin nodes to obtain its transaction history and the current approaches offer no privacy guarantees to the SPV clients. This work presents T 3 , a trusted hardware-secured Bitcoin full client that supports efficient oblivious search/update for Bitcoin SPV clients without sacrificing the privacy of the clients. In this design, we leverage the trusted execution and attestation capabilities of a trusted execution environment (TEE) and the ability to hide access patterns of oblivious random access machine (ORAM) to protect SPV clients’ requests from potentially malicious nodes. The key novelty of T 3 lies in the optimizations introduced to conventional ORAM, tailored for expected SPV client usages. In particular, by making a natural assumption about the access patterns of SPV clients, we are able to propose a two-tree ORAM construction that overcomes the concurrency limitation associated with traditional ORAMs. We have implemented and tested our system using the current Bitcoin Unspent Transaction Output (UTXO) Set. Our experiment shows that T 3 is feasible to be deployed in practice while providing strong privacy and security guarantees to Bitcoin SPV clients. 

Program obfuscation is a popular cryptographic construct with a wide range of uses such as IP theft prevention. Although cryptographic solutions for program obfuscation impose impractically high overheads, a recent breakthrough leveraging trusted hardware has shown promise. However, the existing solution is based on special-purpose trusted hardware, restricting its use-cases to a limited few. In this paper, we first study if such obfuscation is feasible based on commodity trusted hardware, Intel SGX, and we observe that certain important security considerations are not afforded by commodity hardware. In particular, we found that existing obfuscation/obliviousness schemes are insecure if directly applied to Intel SGX primarily due to side-channel limitations. To this end, we present OBFUSCURO, the first system providing program obfuscation using commodity trusted hardware, Intel SGX. The key idea is to leverage ORAM operations to perform secure code execution and data access. Initially, OBFUSCURO transforms the regular program layout into a side-channel secure and ORAM-compatible layout. Then, OBFUSCURO ensures that its ORAM controller performs data oblivious accesses in order to protect itself from all memory-based side-channels. Furthermore, OBFUSCURO ensures that the program is secure from timing attacks by ensuring that the program always runs for a pre-configured time interval. Along the way, OBFUSCURO also introduces a systematic optimization such as register-based ORAM stash. We provide a thorough security analysis of OBFUSCURO along with empirical attack evaluations showing that OBFUSCURO can protect the SGX program execution from being leaked by access pattern-based and timing-based channels. We also provide a detailed performance benchmark results in order to show the practical aspects of OBFUSCURO.