lkml.org 
[lkml]   [2007]   [May]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Seeding /dev/random not working
    > > > 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...

    And add readings from lm-sensors as well? I guess harddisk and cpu
    temperatures (lower bits) and such are pretty random?


    Folkert van Heusden

    --
    MultiTail est un flexible tool pour suivre de logfiles et execution de
    commandements. Filtrer, pourvoir de couleur, merge, 'diff-view', etc.
    http://www.vanheusden.com/multitail/
    ----------------------------------------------------------------------
    Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-05-29 22:09    [W:0.022 / U:184.924 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site