SGXElide: enabling enclave code secrecy via self-modification

Abstract

Intel SGX provides a secure enclave in which code and data are hidden from the outside world, including privileged code such as the OS or hypervisor. However, by default, enclave code prior to initialization can be disassembled and therefore no secrets can be embedded in the binary. This is a problem for developers wishing to protect code secrets. This paper introduces SGXElide, a nearly-transparent framework that enables enclave code confidentiality. The key idea is to treat program code as data and dynamically restore secrets after an enclave is initialized. SGXElide can be integrated into any enclave, providing a mechanism to securely decrypt or deliver the secret code with the assistance of a developer-controlled trusted remote party. We have implemented SGXElide atop a recently released version of the Linux SGX SDK, and our evaluation with a number of programs shows that SGXElide can be used to protect the code secrecy of practical applications with no overhead after enclave initialization.