Method to generate true random numbers in HDD without additional hardware

A novel method is provided for true random number generation in a hard disc drive (HDD). The method is based on the back electromotive force (BEMF) of voice coil motor (VCM) of a HDD with actuator vibrating on the ramp, whose value is dominated by electrical noise from PCB, electrical components parameters change with environment and servo-mechanical system. With this phenomenon, a BEMF value is used to generate a bit of the random number by determining whether the value is odd or even. The multi-dimensional chi-squared test method is used to verify the randomness of the data. The method is to use just the existing HDD hardware thus without any additional cost, and it can be applied for the application where HDD is not required to spin up during system boot up.