Messages in this thread | | | Date | Fri, 2 Nov 2001 10:05:25 +0000 | From | Pavel Machek <> | Subject | Re: [PATCH] (0/4) Entropy accounting fixes |
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Hi!
> > 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.
Pavel -- Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt, details at http://atrey.karlin.mff.cuni.cz/~pavel/velo/index.html.
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