## Cryptology ePrint Archive: Report 2017/572

MXPUF: Secure PUF Design against State-of-the-art Modeling Attacks

Phuong Ha Nguyen and Durga Prasad Sahoo and Chenglu Jin and Kaleel Mahmood and Marten van Dijk

Abstract: Silicon Physical Unclonable Functions (PUFs) have been proposed as an emerging hardware security primitive in various security applications such as device identification, authentication, and cryptographic key generation. Current so-called `strong' PUFs, which allow a large challenge response space, are compositions of Arbiter PUFs (APUFs), e.g. the $x$-XOR APUF. Wide-scale deployment of state-of-the-art compositions of APUFs, however, has stagnated due to various mathematical and physical attacks leading to software models that break the unclonability property of PUFs. The current state-of-the-art attack by Becker, CHES 2015, shows that the XOR APUF can be broken by modeling its APUF components separately thanks to CMA-ES, a machine learning algorithm, based on reliability information of measured XOR APUF responses. Thus, it is an important problem to design a strong PUF which can resist not only traditional modeling attacks but also Becker's attack. In this paper, we propose a new strong PUF design called $(x,y)$-MXPUF, which consists of two layers; the upper layer is an $n$-bit $x$-XOR APUF, and the lower layer is an $(n+1)$-bit $y$-XOR APUF. The response of $x$-XOR APUF for an $n$-bit challenge $\mathbf{c}$ in the upper layer is inserted at the middle of $\mathbf{c}$ to construct a new $(n+1)$-bit challenge for the $y$-XOR APUF in the lower layer giving the final response bit of the $(x,y)$-MXPUF. The reliability of $(x,y)$-MXPUF can be theoretically and experimentally shown to be twice the reliability of $(x+y)$-XOR PUF. In the context of traditional modeling attacks, when we keep the same hardware size, the security of $(x,y)$-MXPUF is only slightly weaker than that of $(x+y)$-XOR PUF. Our main contribution proves that the $(x,y)$-MXPUF is secure against Becker's attack.

Category / Keywords: implementation / Arbiter physically unclonable function (APUF), modeling attack, propagation criterion, reliability based modeling, XOR APUF

Date: received 12 Jun 2017, last revised 12 Jun 2017

Contact author: dpsahoo cs at gmail com

Available format(s): PDF | BibTeX Citation

Short URL: ia.cr/2017/572

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