On 03/20/2017 02:39 PM, Stephan Müller wrote: > Am Montag, 20. März 2017, 14:28:58 CET schrieb Herbert Xu: > > Hi Herbert, > >> On Mon, Mar 20, 2017 at 12:19:32PM +0530, PrasannaKumar Muralidharan wrote: >>> AF_ALG interface for rng does have seeding support. I think hw_random >>> does not provide seeding support intentionally as I understand that >>> True RNG need not require seeding (please correct me if I am wrong). >> Yes. We should be converting PRNGs in hwrng over to algif_rng. > IMHO this not only applies to the PRNGs in drivers/crypto (which should simply > register with crypto_register_rngs) but also to ~/hacking/sources/linux/arch/ > s390/crypto/prng.c which exports a /dev/prandom file. > > For the seeding, it may make sense to follow the example given with crypto/ > drbg.c using the add_random_ready_callback function. > > Ciao > Stephan > I'll have a look on it. Currently the s390/crypto/prng seeds itself with an algorithm based on the jitter of the very fine granular hardware clock of a s390 machine. There were some thoughts and measurements by an mathematician which let to this algorithm. However, long-term the s390 platform will provide some kind of true hardware random number generator and the idea is to use this for seeding the prng. regards Harald Freudenberger
