A High Security Encryption Circuit Based on Ring Oscillator PUF and Secure Scan Chain

In this paper, a high security encryption circuit based on ring oscillator PUF and secure scan chain is proposed. The circuit is composed of three parts: self-reference ring oscillator, test vectors input and decision module and secure scan chain circuit. The key protection is divided into two stages. In the key generation period, the unique identification information of the chip is generated by a self-reference ring oscillator. In the key transmission phase, the XOR value of the correct scan test vectors and the obfuscation vectors generated by the linear feedback shift register are input into the secure scan chain, which further obfuscates the data. Compared with conventional schemes, the area of the proposed self-reference ring oscillator PUF is effectively reduced. In this event, the innovative combination of PUF and secure scan chain proposed in this paper have limited area to a certain extent, and greatly improved the security. The probability of cracking the key is merely $\left(\frac{1}{32 !}\right)^4 \frac{1}{\left(2^n * 2\right)^{256} * 2^n} \frac{1}{2^n}$.