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#! /bin/sh
### BEGIN INIT INFO
# Provides: urandom
# Required-Start: $local_fs mountvirtfs
# Required-Stop: $local_fs
# Default-Start: S
# Default-Stop: 0 6
# Short-Description: Save and restore the random seed
# Description: Save the random seed on shutdown and restore it on boot,
# to ensure that the seed isn't predicable on startup
# (because the boot process is predictable)
### END INIT INFO
test -c /dev/urandom || exit 0
. /etc/default/rcS
case "$1" in
start|"")
test "$VERBOSE" != no && echo "Initializing random number generator..."
# Load and then save 512 bytes,
# which is the size of the entropy pool
if test -f /var/lib/urandom/random-seed
then
cat /var/lib/urandom/random-seed >/dev/urandom
fi
rm -f /var/lib/urandom/random-seed
umask 077
dd if=/dev/urandom of=/var/lib/urandom/random-seed count=1 \
>/dev/null 2>&1 || echo "urandom start: failed."
umask 022
;;
stop)
# Carry a random seed from shut-down to start-up;
# see documentation in linux/drivers/char/random.c
test "$VERBOSE" != no && echo "Saving random seed..."
umask 077
dd if=/dev/urandom of=/var/lib/urandom/random-seed count=1 \
>/dev/null 2>&1 || echo "urandom stop: failed."
;;
*)
echo "Usage: urandom {start|stop}" >&2
exit 1
;;
esac
exit 0
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