[cryptography] Hardware Randomizer (SE Android)

coderman coderman at gmail.com
Mon Mar 5 00:34:11 EST 2012

On Sun, Mar 4, 2012 at 5:12 PM, Jeffrey Walton <noloader at gmail.com> wrote:
> Hi All,
> I've been reading SE Android's Mobile Capabilities Package
> (http://www.nsa.gov/ia/_files/Mobility_Capability_Pkg_(Version_1.1U).pdf).
> I'm interested in seeing how the NSA collects entropy and produces
> bits.
> So far, the only item of interest is a "hardware randomizer" mentioned
> in section 4.4.4. Thinking about it, I'm not sure what a "hardware
> randomizer" is.

the hardware random source is just a component in application layer
entropy availability, but it would be similar to what you'd in the
twin high bitrate hardware noise sources in the entropy key or the VIA
padlock instructions, and other on die and bus noise sources.

the other elements of applying hardware noise sources are the
bios/kernel driver support, the userspace entropy daemon sanity
checking, processing, mixing, compressing, and feeding into OS entropy
pool, and finally the application layer libraries that consume
/dev/random or /dev/urandom (which now provides /dev/random quality
entropy all the time) without limitation on rate consumed by key
generation, ephemeral rekeying, or high session rates.

there are plenty of ways to screw up at any of these points in the
process. the particulars of what they implement are obviously not
forthcoming :)

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