Messages in this thread | | | Date | Tue, 18 Dec 2007 14:39:00 +1030 | From | David Newall <> | Subject | Re: /dev/urandom uses uninit bytes, leaks user data |
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Theodore Tso wrote: > On Tue, Dec 18, 2007 at 01:43:28PM +1030, David Newall wrote: > >> On a server, keyboard and mouse are rarely used. As you've described it, >> that leaves only the disk, and during the boot process, disk accesses and >> timing are somewhat predictable. Whether this is sufficient to break the >> RNG is (clearly) a matter of debate. >> > > In normal operaiton, entropy is accumlated on the system, extracted > via /dev/urandom at shutdown, and then loaded back into the system > when it boots up.
Thus, the entropy saved at shutdown can be known at boot-time. (You can examine the saved entropy on disk.)
> If you have a server, the best thing you can do is use a hardware > random number generator, if it exists. Fortunately a number of > hardware platforms, such as IBM blades and Thinkpads, come with TPM > modules that include hardware RNG's. That's ultimately the best way > to solve these issues.
Just how random are they? Do they turn out to be quite predictable if you're IBM?
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