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    SubjectRe: /dev/random in 2.4.6
    On Mon, 20 Aug 2001, Helge Hafting wrote:

    > Oliver Xymoron wrote:
    > >
    > > Can I propose an add_untrusted_randomness()? This would work identically
    > > to add_timer_randomness but would pass batch_entropy_store() 0 as the
    > > entropy estimate. The store would then be made to drop 0-entropy elements
    > > on the floor if the queue was more than, say, half full. This would let us
    > > take advantage of 'potential' entropy sources like network interrupts and
    > > strengthen /dev/urandom without weakening /dev/random.
    > It seems to me that it'd be better with an
    > add_interrupt_timing_randomness() function.
    > This one should modify the entropy pool, and add no more to the
    > entropy count than the internal interrupt timing allow,
    > i.e. assume that "the ouside" observed the event that
    > trigged the interrupt. How much is architecture dependent:
    > A machine with a clock-counter, like a pentium, can add
    > a number of bits from the counter, as the timing is
    > documented variable. (There could be several interrupts
    > queued up, the interrupt stacks and routines
    > may or may not be in level-1 cache) Even a conservative approach
    > assuming a lot of worst cases would end up adding _some_.

    Until you've spent a while trying to mount a serious timing attack, I
    think any arguments as to how much entropy is there are just a bunch of
    handwaving. Interrupt generation on an otherwise quiescent machine is
    extremely deterministic.

    "Love the dolphins," she advised him. "Write by W.A.S.T.E.."

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