Tunable FPGA Bitstream Obfuscation with Boolean Satisfiability Attack Countermeasure

Abstract

Field Programmable Gate Arrays (FPGAs) are seeing a surge in usage in many emerging application domains, where the in-field reconfigurability is an attractive characteristic for diverse applications with dynamic design requirements, such as cloud computing, automotive, IoT, and aerospace. The security of the FPGA configuration file, or bitstream , is critical, especially for devices with long in-field lifetimes, where attackers may attempt to extract valuable Intellectual Property (IP) from within. In this article, we propose a tunable obfuscation approach that protects IP from typical bitstream attacks while enabling designers to trade off security with acceptable overhead. We also consider two potential attacks on this protection mechanism: Boolean SAT Attacks on the obfuscation and removal attacks on the protection circuitry. The obfuscation and SAT countermeasure are integrated in a custom CAD framework within a commercial FPGA toolflow and together provide mathematically strong protection against common bitstream attacks. Further, we quantify the difficulty of a removal attack on the protection circuitry through pattern matching and direct bitstream manipulation. The average area, power, and delay overhead for obfuscation with 95% mismatch probability are 18%, 16%, and 8%, respectively, for small combinational circuits, and 1%, 2%, and 5% for larger arithmetic modules.

FPGA Design Deobfuscation by Iterative LUT Modification at Bitstream Level

“…In [11,[35][36][37], combinational logic locking schemes dedicated to FPGAs are presented. The basic idea is to insert key bits to the unused inputs of already instantiated LUTs and define the locked logic that corresponds to the wrong values of the key bits by modifying the LUT's truth table.…”

A Smart Obfuscation Approach to Protect Software in Cloud

“…Zhang et al [10] proposed an obfuscation scheme achieved through varying finite field constructions and primitive element representations. A set of quantitatively evaluable metrics are proposed [11], and Olney et al [12] proposed a tunable obfuscation approach from typical bitstream attacks while enabling designers to trade off security with acceptable overhead. Some researchers considered location-based obfuscation: A framework with geo-obfuscation is proposed [13] to protect users' locations during task assignments; A Proactive Topology Obfuscation (ProTO) system that adopts a detect-then-obfuscate framework is proposed [14]; A location obfuscation method [15] is proposed which is robust to privacy inferences by the service provider regarding route source and destination.…”

Diverse, Neural Trojan Resilient Ecosystem of Neural Network IP

“…This has inspired researchers to develop newer and more sophisticated security protocols, including protocols that are inspired by biology and species diversity. There have been many research endeavors that propose bio-inspired security protocols for the secure deployment of hardware [26,37,59,40] and software [11,4,28], as well as security protocols to protect networks and cyberspace [44,15] and to ensure data privacy and security [22,12]. In general, diversity of a species at the genetic level is necessary for the overall survival of that species.…”

“…For example, given a classiication model for a self driving car, there may be several hundred thousand or even millions of these products in operation, with each one having a similar or identical hardware composition. This has motivated researchers to investigate alternative means of hardware deployment, including mutating or łpatchablež hardware [26,40].…”