ERIC: An Efficient and Practical Software Obfuscation Framework

TL;DR

ERIC is a comprehensive software obfuscation framework that leverages hardware decryption and device-specific keys to protect executables against static and dynamic analysis, suitable for cloud environments.

Contribution

ERIC introduces a hardware-software co-design using PUFs and a hardware decryption engine to provide efficient, general, and practical software obfuscation for cloud computing.

Findings

Hardware decryption engine adds minimal FPGA resource overheads.

LLVM-based encryption slightly increases compile time and executable size.

Prototype successfully demonstrates end-to-end obfuscation on RISC-V platform.

Abstract

Modern cloud computing systems distribute software executables over a network to keep the software sources, which are typically compiled in a security-critical cluster, secret. We develop ERIC, a new, efficient, and general software obfuscation framework. ERIC protects software against (i) static analysis, by making only an encrypted version of software executables available to the human eye, no matter how the software is distributed, and (ii) dynamic analysis, by guaranteeing that an encrypted executable can only be correctly decrypted and executed by a single authenticated device. ERIC comprises key hardware and software components to provide efficient software obfuscation support: (i) a hardware decryption engine (HDE) enables efficient decryption of encrypted hardware in the target device, (ii) the compiler can seamlessly encrypt software executables given only a unique device identifier. Both the hardware and software components are ISA-independent, making ERIC general. The key idea of ERIC is to use physical unclonable functions (PUFs), unique device identifiers, as secret keys in encrypting software executables. Malicious parties that cannot access the PUF in the target device cannot perform static or dynamic analyses on the encrypted binary. We develop ERIC's prototype on an FPGA to evaluate it end-to-end. Our prototype extends RISC-V Rocket Chip with the hardware decryption engine (HDE) to minimize the overheads of software decryption. We augment the custom LLVM-based compiler to enable partial/full encryption of RISC-V executables. The HDE incurs minor FPGA resource overheads, it requires 2.63% more LUTs and 3.83% more flip-flops compared to the Rocket Chip baseline. LLVM-based software encryption increases compile time by 15.22% and the executable size by 1.59%. ERIC is publicly available and can be downloaded from https://github.com/kasirgalabs/ERIC