On design of a highly secure PUF based on non-linear current mirrors

Abstract

Physically Unclonable Functions (PUFs) are lightweight hardware security primitives for generating unique signatures from the unpredictable nature of silicon. However, most of the proposed PUFs have been shown to be vulnerable to modeling attacks, especially against Machine Learning algorithms. A subset of challenge-response pairs can leak the required information to break a PUF due to the presence of a linear separating boundary between the PUF responses. In this paper, we propose a strong and secure PUF based on non-linear current mirrors. The fundamental idea is to propagate a current through two identical chains of non-linear current mirrors. The current through a single stage is shifted by some amount based on the strength of the input current. As the current shift is not a fixed value anymore, strong non-linearity is introduced into the challenge-response relationship. The proposed PUF shows excellent properties upon statistical circuit simulation. The average inter-distance and intra-distance of the proposed PUF are 49.9% and 0.8% respectively. One of the most striking features of the proposed PUF is the low information leakage measured in terms of its modeling attack resistance. By employing Support Vector Machine (SVM) based attacks, we observed that the proposed PUF is almost 10-30x stronger than the delay-based PUFs. Moreover, the current mode nature of the PUF circuit enables low power operation. The proposed PUF consumes about 15% lower energy than an arbiter PUF to produce a single response bit.