From mboxrd@z Thu Jan 1 00:00:00 1970 From: smueller@chronox.de (Stephan =?ISO-8859-1?Q?M=FCller?=) Date: Mon, 20 Mar 2017 14:39:47 +0100 Subject: Question - seeding the hw pseudo random number generator In-Reply-To: <20170320132858.GA27044@gondor.apana.org.au> References: <20170318092554.lggkhfg5eko23o3k@kozik-lap> <20170320132858.GA27044@gondor.apana.org.au> Message-ID: <1509135.hmo2UhaKWe@tauon.atsec.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Am Montag, 20. M?rz 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