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    SubjectRe: [PATCH, RFC 10/12] random: cap the rate which the /dev/urandom pool gets reseeded
    On Sun, Sep 22, 2013 at 03:45:11PM -0700, H. Peter Anvin wrote:
    > I understand the motivation, but I question basing it in a fixed amount of time.

    We already have a threshold based on the amount of the entropy in the
    input pool. I could increase that threshold, but then instead of
    having the entropy hover between say, 192 and 128, it would hover
    between say, 576 and 512. What that means in practice is that there
    will be a higher baseline, but we will still end up reseeding every 10
    seconds or so (that being approximately how much entropy I've seen
    flowing into the input pool on my laptop system --- 64 bits every 10
    seconds or so).

    By basing it on a time-based threshold, it means that the input pool
    can build up faster such that over time, such that entropy pool ends
    up hovering around 3400 bits.

    What is your concern is about having it being time-based --- or more
    accurately, being partially time-based, since we also keep the entorpy
    count based threshold? I'll note that the Fortuna Random Number
    Generator, devised by Bruce Schneier and Niels Ferguson also uses as
    part of its design a time-based reseed limit.

    - Ted


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