I was wondering if there happens to be any available documentation or report concerning the pseudo-random number generator functionality within the cryptographic security engine of the S32K1 microcontroller?
①Random numbers shall be generated by a deterministic random bit generator (DRBG), also known as a cryptographically safe pseudo random number generator (CSPRNG) or generated directly by a Hardware Rando Number Generator (TRNG).
If a TRNG is not used, the random number generator used shall be one of the hash based or block cipher base generators approved by NIST, see SP 800-90A. That is Hash_DRBG, HMAC_DRBG or CTR_DRBG. The generator Dual_EC_DRBG must not be used.
②The output from the random number generator shall be tested with the tool Dieharder. When tested, no test shall fail independent of ECU mode (like after a reboot).
③The output from the entropy source used as a seed to the DRBG must be tested using the tool ENT. The entropy generated when tested with ENT MUST be:
- - Entropy: At least 7.5 bits per character or higher.
- - Compression: 0%
- - Chi-Square: Between 200 and 400 and randomly exceed more than 10% and less than 90% of the time.
- - Mean value: Between 126 and 128
- - Monte Carlo: Max 0.5% error
- - Serial correlation: 0.1 or lower
④The Deterministic Random Bit Generator (DRBG) must be initially seeded and periodically reseeded with entropy provided by the entropy source. The reseeding of the DRBG shall be performed in accordance with NIST, SP 800-90A for the used DRBG mechanism.
The initial seed to the DRBG must not be static and shall be different after every reset.
