Re: TPMs and random numbers

[H. Peter Anvin]

This of course has been a long-running debate.  Similarly, we could make much better use of RDRAND if instead of doing data reduction in rngd we could feed it to the pool and just credit fractional bits.  The FIPS tests that rngd runs are weak and obsoleted, but perhaps better than nothing (now when we don't shut down rngd due to false positives.)

Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>On Wed, Sep 11, 2013 at 12:06 PM, Jeff Garzik <jgarzik@xxxxxxxxx>
>wrote:
>> On Wed, Sep 11, 2013 at 2:45 PM, Theodore Ts'o <tytso@xxxxxxx> wrote:
>>> We should definitely do this.  If the TPM driver could fetch some
>>> randomness and then call add_device_randomness() to feed this into
>the
>>> random driver's entropy pool when it initializes itself, that would
>be
>>> ***really*** cool.
>>
>>
>> rngd already does this.
>
>And all those random numbers generated before rngd starts are quite
>possibly crap.
>
>I think that rngd makes sense as a tool to access strange sources of
>entropy and to periodically reseed the pool, but I also think that the
>kernel should really be pulling in easily available entropy on its own
>at startup.
>
>--Andy

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