ST STM32L4+ Series Reference Manual page 1088

True random number generator (RNG) applied to STM32L4P5xx and STM32L4Q5xx only RM0432
33.6 RNG entropy source validation
33.6.1 Introduction
In order to assess the amount of entropy available from the RNG, STMicroelectronics has
tested the peripheral using German BSI AIS-31 statistical tests (T0 to T8), and NIST SP800-
90B test suite. The results can be provided on demand or the customer can reproduce the
tests.
33.6.2 Validation conditions
STMicroelectronics has tested the RNG true random number generator in the following
conditions:
•
RNG clock rng_clk= 48 MHz
•
RNG configurations described in
certified NIST SP800-90B.
RNG
NISTC RNG_CONFIG1
Config
bit
A 0
B 1
1. When writing this register magic number 0x17590ABC must be written immediately before the indicated value
33.6.3 Data collection
In order to run statistical tests it is required to collect samples from the entropy source at raw
data level as well as at the output of the entropy source. For details on data collection and
the running of statistical test suites refer to "STM32 microcontrollers random number
generation validation using NIST statistical test suite" application note (AN4230) available
from www.st.com.
Contact STMicroelectronics if above samples need to be retrieved for your product.
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Table 223. RNG configurations
RNG_CR bits
CLKDIV RNG_CONFIG2
[5:0] [3:0]
0x0F 0x0
0x18 0x0
Table 223. Note that only configuration A can be
RNG_CONFIG3
[2:0] [3:0]
0x0 0xD
0x0
RM0432 Rev 6
Nb
loop
CED
(N)
bit
0 2
0x0 0 2
RNG_HTCR
(1)
register
0x0000
A2B3