DynSGX: A Privacy Preserving Toolset for Dynamically Loading Functions into Intel(R) SGX Enclaves

Abstract: Intel(R) Software Guard eXtensions (SGX) is a hardware-based technology for ensuring security of sensitive data from disclosure or modification that enables user-level applications to allocate protected areas of memory called enclaves. Such memory areas are cryptographically protected even from code running with higher privilege levels. This memory protection can be used to develop secure and dependable applications, but the technology has some limitations: ($i$) the code of an enclave is visible at load time, ($ii$) libraries used by the code must be statically linked, and ($iii$) the protected memory size is limited, demanding page swapping to be done when this limit is exceeded. We present DynSGX, a privacy preserving tool that enables users and developers to dynamically load and unload code to be executed inside SGX enclaves. Such a technology makes possible that developers use public cloud infrastructures to run applications based on sensitive code and data. Moreover, we present a series of experiments that assess how applications dynamically loaded by DynSGX perform in comparison to statically linked applications that disregard privacy of the enclave code at load time.