Research on CRO Technology Based on Mesh Topology Structure

Physical Unclonable Function (PUF) is highly efficient in applications such as device authentication and secure key storage. This paper proposed a design of constructing a configurable ring oscillator unit based on the mesh topology. The dynamic configuration inside the unit increases the number of oscillation frequencies, which increases the complexity of the PUF's challenge-response behavior, thus improving its anti-modeling attack capabilities. According to the analysis of security, as the number of oscillators and frequencies generated by the RO unit increase, the times of attack required breaking the PUF increases exponentially. The experiment shows that the proposed design has higher robustness (99.224%) and uniqueness (50.2%). Introduction The introduction of Physical Unclonable Function (PUF) provides a new idea for solving information security problems. In the digital circuit PUF, the Ring Oscillator-based PUF(ROPUF) breaks through the limitation of the arbiter PUF to require high symmetry in layout routing, and can overcome the requirement that the SRAM PUF generate a response value every time the circuit needs to be restarted, ROPUF can be flexibly applied to security protection [1] . Therefore, research on ROPUF is of great significance. In order to improve the applicability of ROPUF in the application of security protection, domestic and foreign scholars mainly study the key factors affecting the performance of ROPUF, and propose many improved ROPUF structures [2][3][4] . Literature [2] proposed a method for selecting frequency of adjacent RO units to compensate the adverse effects of system process differences on ROPUF uniqueness, and designed a configurable ring oscillator (CRO) Structure to match the noise reduction method. This method increases the constraints of the ROPUF structure, reduces the number of challenge-response pairs (CRP) that can be generated, and does not consider the impact of the design on the ROPUF resistance to attack. Literature [3] proposed an optimal delay algorithm to improve ROPUF resistance to modeling attacks by increasing CRP space. However, the impact of environmental factors on the performance of ROPUF is not taken into consideration, and the frequency of the RO unit structure resulting from its improvement is less, and the efficiency of CRP space expansion is not high. Literature [4] proposed a frequency scheduling scheme based on Lehmer-gray coding for the drawbacks of traditional ROPUF [1] when it was applied to key generation, such as large noise and low entropy density. The module occupies a large amount of resources and has poor applicability to resource-constrained physical entities. Most of the above solutions are based on the static response generation mechanism. The PUF circuit design is not very secure [1] , and there is a general situation of low resource utilization. In view of this, this paper proposes a design of configurable RO based on mesh topology (MC-RO). Through the test experiments, the uniqueness and robustness of ROPUF were quantitatively analyzed. The results showed that the design of MC-RO unit significantly improves PUF security, uniqueness, and robustness.