On Wednesday 24 August 2011 00:53:06 Michael Uleysky wrote: > 2011/8/24, luxInteg <[email protected]>: > > Greetings , > > > > I would be grateful if someone could advise on the saving and > > retrieving of > > the random seed on a BLFS installation and if the random-seed cant > > be saved how does one generate one on boot from say time sources or > > whatever. ( > > when the only writable area is /tmp) > > Do you mean seed for /dev/urandom? > If so, you can use following script > > # Get number of seconds since epoch (or date in any other format). > D=`date +%s` > # Get some (pseudo)random data (better to use /dev/random instead of > /dev/urandom but this may be dangerous if /dev/random does'nt have > sufficiently amount of random data). > R=`dd if=/dev/urandom count=64 bs=1 2>/dev/null` > # Calculate sha512 hash of concatenation of our two data. It will be > our random seed. > St=`echo -n "$R$D"|sha512sum -b|sed "s/ .*//"` > # Convert hash to string with hexes. > S=`echo $St|sed -r 's/([0-9a-f]{2})/\\\\x\1/g'` > # Write our seed in binary form to /dev/urandom. > echo -ne $S>/dev/urandom > > So, you generate a seed which depends on current time and random data. > > Michael Uleysky
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