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    SubjectRe: /dev/urandom uses uninit bytes, leaks user data
    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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      Last update: 2007-12-18 05:11    [W:0.032 / U:0.148 seconds]
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