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    SubjectRe: [BUG] perf: bogus correlation of kernel symbols

    * Ray Lee <> wrote:

    > On Mon, May 23, 2011 at 3:49 AM, Ingo Molnar <> wrote:
    > > Well, since entropy does not get reduced on addition of independent variables
    > > the right sequence is (pseudocode):
    > >
    > >        rnd  = entropy_cycles();
    > >        rnd += entropy_rdrand();
    > >        rnd += entropy_RTC();
    > >        rnd += entropy_system();
    > I think you mean concatenation rather than addition? Or perhaps XOR, or a
    > hash? [...]


    In this special case probably concatenation works the best: the above 4 random
    variables have total randomness probably less than 32 bits, so we want to
    create 4 tight random numbers and concatenate them.

    [ XOR would destroy some fair amount of entropy because most of these random
    variables have their randomness in their low bits, and a hash would probably
    lose about 2 bits and would also be slower. A hash would probably be safer
    and more robust though, if we mis-identify any of the random variables. ]


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