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    SubjectRe: [PATCH] API for true Random Number Generators to add entropy (2.6.11)
    On Mar 29, 2005, at 17:02, Bill Davidsen wrote:
    > Wait a minute, if it fails the system drops back to software,

    Does it? It would seem that if it fails and begins returning
    all zeroes, then the seed function would (depending on the
    implementation) be called like this:

    add_random_bytes("\0\0\0\0".... , 4096);
    add_random_bytes("\0\0\0\0".... , 4096);


    add_random_bytes("\0\0\0\0".... , 4096);
    add_random_bytes(soft_random() , 64);
    add_random_bytes("\0\0\0\0".... , 4096);
    add_random_bytes(soft_random() , 64);

    In either case, it's very bad, and will likely return cause
    some _very_ predictable data to be emitted.

    > I'm not sure you would get people to agree what should be
    > done if a hardware RNG fails, other than make the failure
    > information available to user space.

    How do you know if it fails? You know when your disk fails
    and begins giving bad data because the filesystem detects
    that the data is invalid, but how do you tell when your
    random number generator starts giving bad data? AFAIK, the
    only way to do that is to continuously monitor the random
    data produced and _immediately_ stop the data flow when
    you start getting bad data. That should only be done from
    a userspace rngd-type daemon.

    Kyle Moffett

    Version: 3.12
    GCM/CS/IT/U d- s++: a18 C++++>$ UB/L/X/*++++(+)>$ P+++(++++)>$
    L++++(+++) E W++(+) N+++(++) o? K? w--- O? M++ V? PS+() PE+(-) Y+
    PGP+++ t+(+++) 5 X R? tv-(--) b++++(++) DI+ D+ G e->++++$ h!*()>++$ r
    ------END GEEK CODE BLOCK------

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