Am Donnerstag, 23. März 2017, 09:03:23 CET schrieb Harald Freudenberger: Hi Harald, > 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. It takes a page and simply writes 512 times the high-res time stamp using get_tod_clock_fast into it. Effectively it uses the same fundamental noise source as the jitterentropy. (A couple of months ago I had to perform an SP800-90B assessment on exactly that code path. :-) ) > 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. The question is just that it provides a device file nobody else provides. And the question is whether to consolidate it. If it is a DRNG, the discussion is about consolidating it behind AF_ALG. If it is an RNG with its own noise source (i.e. it provides entropic data by itself), it should rather be placed into drivers/char/hw_random and use the hw-random framework. This framework will also ensure that it may seed the /dev/random device kernel-internally. Ciao Stephan
