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    SubjectRe: [PATCH] (0/4) Entropy accounting fixes

    > > What entropy can be measured from disk timings are very often leaked
    > > by immediately relaying data to web, shell, or X clients. Further,
    > > patterns of drive head movement can be remotely controlled by clients
    > > talking to file and web servers. Thus, while disk timing might be an
    > > attractive source of entropy, it can't be used in a typical server
    > > environment without great caution.
    > This is something to be concerned about, to be sure. But generally a
    > client won't have complete control of the drive head movement ---
    > there are other clients involved --- and the adversary generally won't
    > have complete knowledge of the block allocation of files, for example,
    > so he/she would not be able to characterize the disk drive timings to
    > the degree of accuracy required.

    You seem assume that adversary is on remote system. That's not neccessarily
    the case.

    Imagine you wanting to generate gpg key while I have normal user account
    on the machine. I can sample /proc/interrupts, measure disk speeds etc...
    Perhaps we are alone on [otherwise idle] machine. You still don't want me
    to guess your key.

    Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt,
    details at

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