This paper addresses the effect of aging on linear and non-linear MUX physical unclonable functions (PUFs). It is well known that a PUF response can be modeled in terms of the delay difference of MUX stages. In this paper, we show that the aging effects can be modeled in terms of variations in delay-difference and arbiter delay. Specifically, with aging, the percent delay-difference variation of each MUX stage can be modeled as a ratio of two correlated Gaussian random variables. This ratio distribution is shown to be approximately Gaussian with zero mean and variance increasing with time. In case of the arbiter, the ratio distribution is modeled as a Gaussian with positive mean. The paper makes three contributions: modeling the effect of aging in terms of percent variations in delay-difference of the MUX stages and arbiter delay, analysis of authentication accuracy with aging, and approaches to increase the PUF's lifetime by either recalibrating it to obtain new delay-difference parameters, or by tuning a threshold based on the total delay-difference. A general approach for selecting the threshold values is described in the paper. It is shown that the authentication accuracy of a PUF is significantly affected due to aging effects of the arbiter itself. Therefore, under the assumption that the variations in arbiter delay are considerably more than in delay-differences, the performance degradation in the case of aging alone is prominent compared to noise alone. We show that the authentication accuracy of a feed-forward PUF is more degraded compared to linear or modified feed-forward PUF. Metrics like Jenson-Shannon and Henze-Penrose divergence are also used to analyze the effect of aging.
|Original language||English (US)|
|Title of host publication||ASP-DAC 2018 - 23rd Asia and South Pacific Design Automation Conference, Proceedings|
|Publisher||Institute of Electrical and Electronics Engineers Inc.|
|Number of pages||8|
|State||Published - Feb 20 2018|
|Event||23rd Asia and South Pacific Design Automation Conference, ASP-DAC 2018 - Jeju, Korea, Republic of|
Duration: Jan 22 2018 → Jan 25 2018
|Name||Proceedings of the Asia and South Pacific Design Automation Conference, ASP-DAC|
|Other||23rd Asia and South Pacific Design Automation Conference, ASP-DAC 2018|
|Country||Korea, Republic of|
|Period||1/22/18 → 1/25/18|
Bibliographical noteFunding Information:
This research has been supported by the National Science Foundation under grant number CNS-1441639 and the semiconductor research corporation under contract number 2014-TS-2560.
∗This research has been supported by the National Science Foundation under grant number CNS-1441639 and the semiconductor research corporation under contract number 2014-TS-2560.
- Divergence metrics
- Physical Unclonable Function
- Statistical Modeling