Investigation of ROPUF with Improved Temperature Performance on FPGA

Author Name(s): Aman Pandey, Sandeepkumar Pandey
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Physically Unclonable Function (PUF) is one of the better known security tool used for safety of electronic devices. Among several PUF designs, Ring Oscillator Physically Unclonable Function (ROPUF) is one of the most favoured PUF design and it can be easily implemented in Field Programmable Gate Array (FPGA). It is evident from the literature that change in the temperature causes more error in the PUF responses. In this work, our aim is to make a ROPUF which can be implemented on FPGA with better temperature performance in output PUF bit generation. Designs are implemented on same FPGA and its reliability is checked at varying room temperatures. In fact, due to temperature variations further uniqueness can be achieved which will help to build stronger ROPUF. Spartan 6 FPGA boards were used to test the proposed PUF architecture and the system outputs were statistically evaluated proving the suitability of the proposed PUF design for device identification in real world.

Keywords Physically Unclonable Function (PUF), FPGA, Ring Oscillator


Mobile and various electronics devices are omnipresent as they are interconnected for several day to day tasks. Overwhelming growth in Electronics and Internet of Things (IoT’s) has resulted in multiple issues regarding security. IoT will become established element of our life making security concern more important. Hence to resolve this problem Cryptography is used, which uses a secret key but Cryptography is a classical approach. Cryptography uses a secret key, which is stored in non-volatile memory. As the secret key is stored in Non-Volatile memory, the secret key is domitable. This eventually means that such security measures are not reliable and there is a necessity of a safer and indomitable method. In past few years Physical Unclonable Function (PUFs) is considered as propitious security application. The interest in PUF has increased exponentially which has made it a talking point in the field of hardware security. It works on the principle of Process Variations and these Process Variations can neither be duplicated nor they are controllable but can be evaluated and used for device identification effectively.



In this paper, RO based PUF with improved temperature performance is proposed, which is providing unique output bits despite change in room temperature or change in temperature due to operation of device. Hence this ROPUF is not strongly dependent on change in temperature. Since there is differential structure in architecture, this cancels out common mode disturbances (ex Temperature) in operating conditions. ROPUF is also not dependent on placement of RO on FPGA implying that it is easy to implement under any operating conditions. This way output bit patterns which are more immune to environmental variations is obtained. This ROPUF design selects suitable bits for PUF from counter values obtained from the measurements on various RO pairs. Using this technique, bits from each RO pair were obtained which as a result are stable and unique bit. Therefore more reliable PUF can be implemented. According to the results, it is evident that this ROPUF design is suitable for addressing problem of identification of Integrated circuits in real world as PUF runs with full effectiveness even under environmental variations in temperature.

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