Proposal and Analysis of a Novel Class of PUFs Based on Galois Ring Oscillators

Abstract

In this paper, the possibility of using Galois ring oscillators to construct physically unclonable functions (PUFs) has been studied. The idea is to use novel PUF architectures, similar as the ring oscillator PUFs that, instead of comparing frequencies, compare the statistical bias of pairs of oscillators implemented in different locations. To study the viability of these systems, three different Galois oscillators have been implemented in several locations in several FPGAs and we have studied the main properties of their bias: repeatability, variability with the location, variability with the FPGA and spatial autocorrelation. Based on this study, we have determined that the bias of these oscillators meet the requirements that are needed to be used to construct a PUF. Finally, a PUF based on comparing the bias of neighboring 7-LUT Galois ring oscillators have been implemented and analyzed. The experimental results show that this PUF generates uniform responses that are highly reproducible and unique, making this PUF suitable for being used in identification applications. INDEX TERMS Fibonnaci ring oscillators, FPGA, Galois ring oscillators, hardware security, physically unclonable function, ring oscillator. Identificability Random variations due to manufacturing process Physical unclonability PUF Challenges Responses • Easy implementation • Low-power consumption • "Volatile secret"

Suitability of Generalized GAROs on FPGAs as PUFs or TRNGs Considering Spatial Correlations

“…In [18], it was shown experimentally that the bias of GAROs changed with their location in a reproducible way and, therefore, they could be used to construct a PUF. As a proof of concept, a 7-LUT PUF that compared the bias of neighboring GAROs was implemented achieving an average Intra-chip Hamming Distance (Intra-HD) of ~1 % and an average Inter-chip Hamming Distance (Inter-HD) of ~39 %.…”

“…Furthermore, some works have proven that the behavior of these systems can greatly depend on the location within the FPGA so that, in certain locations, these systems can present poor randomness results [17]. Based on this fact, [18] studied the possibility of using the variations with the location presented by the GAROs to construct a PUF. That work showed that the bias of these systems varied with the location in a similar manner as the frequencies of a ring oscillator and, therefore, it was possible to use GAROs to construct a PUF in an analogous manner as an RO-PUF but comparing biases instead of frequencies.…”

Review of Physically Unclonable Functions (PUFs): Structures, Models, and Algorithms

“…In order to increase the CRP space and hence improve security we propose a modified RO derived form a Galois linear feedback shift register (LFSR). A complementary design can be found in Garcia-Bosque et al (2020). In the design of Garcia-Bosque et al ( 2020) the inverters and XOR gates are connected in series and are always in the path of the system.…”

Physical Unclonable Function Based on the Internal State Transitions of a Fibonacci Ring Oscillator

“…It uses complex XOR feedback that is analogous to the Galois, thus creating Galois ring oscillators (GAROs). It is well known that the oscillators implemented in different locations in an integrated circuit present statistically significant differences [ 15 ]. Consequently, a GARO-based PUF compares the value of the bias of the GARO’s state instead of the frequencies of ring oscillators.…”