High-level Intellectual Property Obfuscation via Decoy Constants
This addresses the issue of IP protection for circuit designers against reverse engineering at untrusted foundries, though it is incremental as it builds on existing obfuscation concepts by focusing on constants rather than arbitrary nodes.
The paper tackles the problem of intellectual property theft in integrated circuits by proposing a high-level obfuscation technique that uses decoy constants and a key-based scheme to protect constant multiplications, such as in filters and neural networks, with small overheads in area, power, and delay comparable to existing logic locking methods.
This paper presents a high-level circuit obfuscation technique to prevent the theft of intellectual property (IP) of integrated circuits. In particular, our technique protects a class of circuits that relies on constant multiplications, such as filters and neural networks, where the constants themselves are the IP to be protected. By making use of decoy constants and a key-based scheme, a reverse engineer adversary at an untrusted foundry is rendered incapable of discerning true constants from decoy constants. The time-multiplexed constant multiplication (TMCM) block of such circuits, which realizes the multiplication of an input variable by a constant at a time, is considered as our case study for obfuscation. Furthermore, two TMCM design architectures are taken into account; an implementation using a multiplier and a multiplierless shift-adds implementation. Optimization methods are also applied to reduce the hardware complexity of these architectures. The well-known satisfiability (SAT) and automatic test pattern generation (ATPG) attacks are used to determine the vulnerability of the obfuscated designs. It is observed that the proposed technique incurs small overheads in area, power, and delay that are comparable to the hardware complexity of prominent logic locking methods. Yet, the advantage of our approach is in the insight that constants -- instead of arbitrary circuit nodes -- become key-protected.