Physical random number generators for cryptographic application in mobile devices

We present small random number generators using silicon devices that generate large fluctuating signal as noise source devices. Since the noise signal of these devices is very large, the noise signal can be directly input to an RC oscillator or a differential amplifier without preamplifiers. In this paper, we present a small physical random number generator using an astable multivibrator and post-processing circuits, which can generate excellent quality random numbers suitable for cryptographic applications. We also introduce the concept of random number generator using a filter circuit and a differential amplification for high bit rate application.