STMicroelectronics STM32WL5 Series - Page 632

True random number generator (RNG) RM0453
632/1450 RM0453 Rev 5
22 True random number generator (RNG)
22.1 Introduction
The RNG is a true random number generator that provides full entropy outputs to the
application as 32-bit samples. It is composed of a live entropy source (analog) and an
internal conditioning component.
The RNG is a NIST SP 800-90B compliant entropy source that can be used to construct a
nondeterministic random bit generator (NDRBG).
The RNG true random number generator has been precertified NIST SP800-90B. It has
also been tested using the German BSI statistical tests of AIS-31 (T0 to T8).
22.2 RNG main features
• The RNG delivers 32-bit true random numbers, produced by an analog entropy source
conditioned by a NIST SP800-90B approved conditioning stage.
• It can be used as the entropy source to construct a nondeterministic random bit
generator (NDRBG).
• In the NIST configuration, it produces four 32-bit random samples every 412 AHB clock
cycles if f
AHB
< f
threshold
(256 RNG clock cycles otherwise).
• It embeds startup and NIST SP800-90B approved continuous health tests (repetition
count and adaptive proportion tests), associated with specific error management
• It can be disabled to reduce power consumption, or enabled with an automatic low
power mode (default configuration).
• It has an AMBA
®
AHB slave peripheral, accessible through 32-bit word single
accesses only (else an AHB bus error is generated, and the write accesses are
ignored).