>> > > OTOH, why people don't just read a pile of bytes from /dev/audio
Yep this is what I do. I have a host with a sound card located in a busy
office. I grab sound samples from this system at regular intervals.
The script below takes care of the grunt work and may be of use
to others wanting a reasonable source of randomness. Only works
for *nix - sorry.
--sjg
[the missing funcs.sh etc are included in
ftp://ftp.quick.com.au/pub/unix/config-sh.cpio.gz]
:
# NAME:
# getnoise - get some random noise
#
# DESCRIPTION:
# Grab some sound bytes from a machine with a sound card.
# The random? noise from the sound card is compressed and
# appended to a big file.
#
# We then take sequential 1k chunks from the start of the random
# store to update all the .rand files we know of. The idea is
# that it should be difficult to predict when the sound sample
# in any given .rand file was actually collected.
#
# Each 1k chunk of random data is used only once and the random
# storage file is kept from growing too big by stripping of used
# and excess data at the start of the file. The skipping of
# excess data means there is no guarantee that any particular
# sample will be used.
#
# AUTHOR:
# Simon J. Gerraty <[EMAIL PROTECTED]>
# RCSid:
# $Id: getnoise,v 1.8 1998/11/19 14:00:51 sjg Exp $
#
# @(#) Copyright (c) 1997 Simon J. Gerraty
#
# This file is provided in the hope that it will
# be of use. There is absolutely NO WARRANTY.
# Permission to copy, redistribute or otherwise
# use this file is hereby granted provided that
# the above copyright notice and this notice are
# left intact.
#
# Please send copies of changes and bug-fixes to:
# [EMAIL PROTECTED]
#
Myname=getnoise
# pick up zap()
RC_D=${RC_D:-/etc/rc_d}
. $RC_D/funcs.sh
source .${Myname}rc $Mydir $RC_D /etc
case "$NOISE_HOST" in
""|localhost*|${DEST_HOST:-$HOST})
RSH="/bin/sh -c";;
*) RSH="${SSHELL:-SSLrsh -zcert=/etc/host.cert} $NOISE_HOST";;
esac
NOISE_STORE=${NOISE_STORE:-/.random}
TF=${TMP:-/tmp}/gn$$
if [ -s $NOISE_STORE ]; then
# grab a reasonable sample
count=${NOISE_SAMPLE:-12}
# Work out how much to skip to keep the file under $NOISE_KEEP
sz=`du $K -s $NOISE_STORE`
sz=`set -- $sz; echo $1`
skip=`expr ${sz:-0} - ${NOISE_KEEP:-120}`
[ $skip -lt 0 ] && skip=0
else
# grab a bigger sample to start us off.
count=${NOISE_SAMPLE1:-32}
fi
# this works whether /dev/audio is local or not
# we compress first so we know how much data we get...
eval $RSH "'compress < ${DEV_AUDIO:-/dev/audio} | dd bs=1k count=$count'" >>
$NOISE_STORE 2> $TF
egrep -v 'records|bytes' $TF >&2
[ -s $NOISE_STORE ] && (locate .rand; locate .rnd) | grep -v $NOISE_STORE | awk '{
print "test -s", $0, "&& dd bs=1k skip=" NR, "count=1 <", NOISE, ">", $0 } END { print
"mv", NOISE, NOISE ".old && dd bs=1k skip=" NR + SKIP, "<", NOISE ".old >", NOISE }'
NOISE=$NOISE_STORE SKIP=${skip:-0} - | sh > /dev/null 2>&1
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