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    SubjectRe: Seeding /dev/random not working
    On 5/29/07, Pavel Machek <pavel@ucw.cz> wrote:
    > Hi!
    >
    > > > I have two embedded boards (one ARM, one PowerPC), running two
    > > > different versions of 2.6. They have no hard drives, keyboards or
    > > > mice. They each have a NIC, but I understand these make no
    > > > contribution to the entropy pool.
    > > >
    > > > if [ -f $random_seed ]; then
    > > > cat $random_seed >/dev/urandom # should seed the pool
    > > > fi
    > > > dd if=/dev/urandom of=$random_seed count=1 2>/dev/null # save some
    > > > data from urandom for next boot
    > > >
    > > > I have rebooted my boards many times, and after each boot I read the
    > > > contents of $random_seed. Whilst it does not happen every time, the
    > > > contents of $random_seed are /often the same/. To give you a feel:
    > > > rebooted 11 times, got a total of 3 different outputs.
    > >
    > > Ok, so this is telling me a couple of things. First of all, if you're
    > > only getting three outputs, it means that you don't have any
    > > peripherals feeding entropy into the system from the boot sequence.
    > > Without any hard drives, keyboards or mice, and a NIC whose device
    > > driver hasn't been configured to feed entropy, you're definitely
    > > hosed.
    >
    > Can we get at least time-of-boot from rtc clock to the pool? We really
    > should not be getting identical outputs...

    Ah yes that is one thing I forgot to mention - when you turn these
    boards off, you really do turn them off - no battery means no clock.
    They wake up every time in 1970.

    I am planning on providing my own entropy to this system by feeding
    /dev/random (which leads to the problem of it not working...).
    -
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