The research into ring oscillator physically unclonable functions (RO-PUF) continues to expand due to its simple structure, ease of generating responses, and its promises of primitive security. However, a substantial study has yet to be carried out in developing designs of the FPGA-based RO-PUF, which effectively balances performance and area efficiency. This work proposes a modified RO-PUF where the ring oscillators are connected directly to the counters. The proposed RO-PUF requires fewer RO than the conventional structure since this work utilizes the direct pulse count method. This work aims to seek the ideal routing density of ROs to improve uniqueness. For this purpose, five logic arrangements of a wide range of routing densities of ROs were tested. Upon implementation onto the FPGA chip, the routing density of ROs are varied significantly in terms of wire utilization (higher than 25%) and routing hotspots (higher than 80%). The best uniqueness attained was 52.71%, while the highest reliability was 99.51%. This study improves the uniqueness by 2% subsequent to the application of scenarios to consider ROs with a narrow range of routing density. The best range of wire utilization and routing hotspots of individual RO in this work is 3–5% and 20–50%, respectively. The performance metrics (uniqueness and reliability) of the proposed RO-PUF are much better than existing works using a similar FPGA platform (Altera), and it is as good as the recent RO-PUFs realized on Xilinx. Additionally, this work estimates the minimum runtimes to reduce error and response bit-flip of RO-PUF.

For a long time, random numbers have been used in many fields of application. Much work has been conducted to generate truly random numbers and is still in progress. A popular method for generating random numbers is a linear-feedback shift register (LFSR). Even though a lot of work has been done using this method to search for truly random numbers, it is an area that continues to attract interest. Therefore, this paper proposes a circuit for generating random numbers. The proposed circuit is designed to produce different sequences of numbers. Two segments of Fibonacci LFSR are used to form a generator that can produce more varied random numbers. The proposed design consists of blocks: segment 1, segment 2, and a clock controller. The system produces random numbers based on an external clock. The clock signal for the first segment is that of the external clock, whereas that for the second segment is modified by the clock controller. The second stage (segment 2) is executed only after every 2n1−1 clock cycles. The proposed design can generate different sequences of random numbers compare to those of the conventional methods. The period of the proposed system is less than that of the original Fibonacci LFSR. However, the period is almost equal to the original one when the system is realized in 32-bit or 64-bit form. Finally, the proposed design is implemented on a field-programmable gate array (FPGA). It occupies more area and runs at a lower frequency compared with the original Fibonacci LFSR. However, the proposed design is more efficient than the segmented leap-ahead method concerning space occupancy.

The main issue of ring oscillator physical unclonable functions (RO-PUF) is the existence of unstable ROs in response to environmental variations. The RO pairs with close frequency differences tend to contribute bit flips, reducing the reliability. Research on improving reliability has been carried out over the years. However, it has led to other issues, such as decreasing the uniqueness and increasing the area utilized. Therefore, this paper proposes a uniform RO-PUF, requiring a smaller area than a conventional design, aiming to balance reliability and uniqueness. We analyzed RO runtimes to increase reliability. In general, our method (uniqueness = 47.48%, reliability = 99.16%) performs better than previously proposed methods for a similar platform (Altera), and the reliability is as good as the latest methods using the same IC technology (28 nm). Moreover, the reliability is higher than that of RO-PUF with challenge and response pair (CRP) enhancements. The evaluation was performed in longer runtimes, where the pulses produced by ROs exceeded the counter capacity. This work recommends choosing ranges of the runtime of RO for better performance. For the 11-stage ROs, the range should be 1.598–4.30 ms, or 6.12–8.61 ms, or 12.24–12.91 ms. Meanwhile, for the 20-stage, the range should be 2.717–8.37 ms, or 10.97–16.74 ms, or 21.93–25.10 ms.

The paper discusses the effect of capacitance changes on the ring oscillator to its output wave for a physically unclonable function (PUF) application. The wave quality generated by the ring oscillator (RO) will largely determine the response of PUF. We have analyzed the resulting RO waveforms to determine the capacitor values and the ideal number of RO stages. The peak voltage analysis of the capacitance change has been done with the help of the Mentor Graphics software package. High performance PTM model transistors (16nm, 22nm, 32nm, and 45nm technologies) are selected to form the RO circuit. Based on the results of the study, we recommend that the number of RO stages is at least 5. Then, we also recommend the ideal capacitance value as a compromise between quality and delay. The capacitances should be 0.7fF, 0.8fF, 0.9fF, and 1fF for 16nm, 22nm, 32nm, and 45nm technologies, respectively.

Research on the possibility of using Ring Oscillator (RO) as a Physically Unclonable Function (PUF) has been carried out. However, until now, nothing has been realized because none of them meets the expected reliability. One of the factors that influence its reliability is the variety of routing hotspots. This paper proposes a technique for uniformizing routing hotspots in all RO locations. Ten ROs are placed close to each other, and each of them is equipped with a counter. Four variations in the arrangement of RO inside a Logic Array Blocks (LAB) are created. Then, routing hotspots in all RO locations are designed to be uniform. The uniformity process is done by rearranging the location of the logic fan-in and fan-out of the RO and counter. RO is activated vary from 0.4ms to 2ms. The number of pulses generated by ROs are recorded. Based on experiments on four Cyclone V chips, the average uniqueness was 43.79% and 46.04% for 5-stage and 11-stage RO, respectively. Reliability of 11-stage RO is higher when tested between 25°C and 40°C.

The increasing of mobile applications makes it easier for humans to get up to date information. Users are accustomed to searching for an answer from the virtual world, including health problems. This paper discusses the mobile application of skin disease analysis based on the image. The system requires two images, unhealthy and healthy skin images. The system designed to analyze the unhealthy image and use the second one as a reference. Edge detection of the two images will be compared by finding the difference in Mean value. The difference in mean value will be put forward in the decision-making against suspected unhealthy skin that being analyzed. The app was built with Android Studio with an OpenCV library for implementing the Canny edge detection. Android-based mobile applications have been successfully created, and it is able to analyze the skin image. However, base on analysis, it is required further testing to find the appropriate parameters.