NXP Semiconductors K32 L2A Series, Reference Manual, Page: 1211 / 1379

Chapter 48
SA-TRNG Standalone
48.1 Standalone True Random Number Generator (SA-
TRNG).
The Standalone True Random Number Generator (SA-TRNG) is a hardware accelerator
module that generates a 512-bit entropy as needed by an entropy-consuming module or
by other post-processing functions. A typical entropy consumer is a pseudo random-
number generator (PRNG) that can be implemented to achieve both true randomness and
cryptographic-strength random numbers using the TRNG output as its entropy seed. The
PRNG is not part of this module.
The entropy generated by a TRNG is intended for direct use by functions that generate
secret keys, per-message secrets, random challenges, and other similar quantities used in
cryptographic algorithms. In each of these cases, it is important that a random number be
difficult to guess or predict. It is important that a random number is at least as difficult to
predict as it is difficult to break the cryptographic algorithm with which it is being used.
This stringent requirement is particularly difficult to fulfill if the entropy source from a
TRNG contains bias and/or correlation. To increase the trustworthiness/quality of the
generated random data, PRNGs are often used to post process the output of a TRNG.
This document describes only the TRNG design functionality and usage.
Note that before entropy can be obtained from the TRNG, it must be initialized and
instantiated in a particular mode by setting the appropriate TRNG registers.
The TRNG contains the following sub modules: IP Slave bus (SkyBlue bus) interface, the
TRNG Core and the free running oscillator (OSC).
48.1.1 Standalone True Random Number Generator Block
Diagram
The following figure is a top-level diagram of the True Random Number Generator.
K32 L2A Reference Manual, Rev. 2, 01/2020
NXP Semiconductors 1211