Re: [PATCH] API for true Random Number Generators to add entropy (2.6.11)

[Jeff Garzik <jgarzik@pobox.com>]

Evgeniy Polyakov wrote:
> On Thu, 2005-03-24 at 23:23 +1000, David McCullough wrote:
>
> > Jivin Jeff Garzik lays it down ...
> >
> > > Evgeniy Polyakov wrote:
> > >
> > > > On Thu, 2005-03-24 at 14:27 +1000, David McCullough wrote:
> > > >
> > > >
> > > > > Hi all,
> > > > >
> > > > > Here is a small patch for 2.6.11 that adds a routine:
> > > > >
> > > > > 	add_true_randomness(__u32 *buf, int nwords);
> > > > >
> > > > > so that true random number generator device drivers can add a entropy
> > > > > to the system.  Drivers that use this can be found in the latest release
> > > > > of ocf-linux,  an asynchronous crypto implementation for linux based on
> > > > > the *BSD Cryptographic Framework.
> > > > >
> > > > > 	http://ocf-linux.sourceforge.net/
> > > > >
> > > > > Adding this can dramatically improve the performance of /dev/random on
> > > > > small embedded systems which do not generate much entropy.
> > > >
> > > >
> > > > People will not apply any kind of such changes.
> > > > Both OCF and acrypto already handle all RNG cases - no need for any kind
> > > > of userspace daemon or entropy (re)injection mechanism.
> > > > Anyone who want to use HW randomness may use OCF/acrypto mechanism.
> > > > For example here is patch to enable acrypto support for hw_random.c
> > > > It is very simple and support only upto 4 bytes request, of course it
> > > > is 
> > > > not interested for anyone, but it is only 2-minutes example:
> > >
> > > If you want to add entropy to the kernel entropy pool from hardware RNG, 
> > > you should use the userland daemon, which detects non-random (broken) 
> > > hardware and provides throttling, so that RNG data collection does not 
> > > consume 100% CPU.
> > >
> > > If you want to use the hardware RNG directly, it's simple:  just open 
> > > /dev/hw_random.
> > >
> > > Hardware RNG should not go kernel->kernel without adding FIPS tests and 
> > > such.
> >
> > For reference,  the RNG on the Safenet I am using this with is
> > FIPS140 certified.  I believe the HIFN part  is also but I place the doc that
> > says so.
>
>
> At least HIFN 795x is certified.
>
> Idea to validate entropy data is good in general, 
> but it should be implemented in a way allowing external both in-kernel
> and userspace
> processes to contribute data.
> So for in-kernel use we need such a mechanism, and userspace gkernel
> daemon
> should use it(as the latest "step") too.

See the earlier discussion, when data validation was -removed- from the 
original Intel RNG driver, and moved to userspace.


> Your changes are correct, ioctl(RNDADDENTROPY) could even use it instead
> of direct
> add_entropy_words()/credit_entropy_store(), but without external entropy
> contributors
> it will not be applied by maintainers.

No changes are needed, as the system is currently functional without 
these changes.

	Jeff


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