Collecting entropy from device_attach() times.

[David O'Brien]

On Wed, Sep 19, 2012 at 03:34:59PM -0700, David O'Brien (@FreeBSD) wrote:
> On Tue, Sep 18, 2012 at 11:14:22PM +0200, Pawel Jakub Dawidek wrote:
> > I experimented a bit with collecting entropy from the time it takes for
> > device_attach() to run (in CPU cycles). It seems that those times have
> > enough variation that we can use it for entropy harvesting. It happens
> > even before root is mounted, so pretty early.
> 
> I like it.  Microsoft harvests from something like 900 events/things.

Some of this is documented in 'Windows 7 CNGSYS FIPS Security Policy.docx' 
Section 5.3.2 "SystemPrng".
[http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/140sp1328.pdf]

should this give anyone more ideas...

-- 
-- David