Chapter 1 Overview of Arm® TrustZone® TRNG
This chapter provides an overview of the Arm® TrustZone® TRNG and its characterization.
Arm TrustZone TRNG collects entropy from a physical entropy source (a component capable of generating an unpredictable or random output bit stream). The collected entropy is used to seed the cryptographic random bits generator with a secure initial state.
NoteUsually, the physical process used for collecting entropy is an inverter timing jitter that is collected from a dedicated on-chip free-running ring oscillator.
The TRNG can be used in one of two modes, each requiring a different driver:
- The operating mode of the Arm implementation of the FE TRNG driver is compliant with the BSI AIS-31: Functionality Classes and Evaluation Methodology for True Random Number Generators standard, as a true random number generator that outputs full-entropy bits at a relatively low rate.
- The operating mode of the Arm implementation of the 800-90B TRNG driver is compliant with the NIST SP 800-90B: Recommendation for the Entropy Sources Used for Random Bit Generation standard, as a true random number generator.
It contains the following sections: