chiark / gitweb /
profile.d/00base: Fix stupid typo.
[distorted-keys] / keys.reveal
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1#! /bin/sh
2###
3### Reveal shares of a secret distributed among keepers
4###
5### (c) 2011 Mark Wooding
6###
7
8###----- Licensing notice ---------------------------------------------------
9###
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10### This file is part of the distorted.org.uk key management suite.
11###
12### distorted-keys is free software; you can redistribute it and/or modify
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13### it under the terms of the GNU General Public License as published by
14### the Free Software Foundation; either version 2 of the License, or
15### (at your option) any later version.
16###
599c8f75 17### distorted-keys is distributed in the hope that it will be useful,
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18### but WITHOUT ANY WARRANTY; without even the implied warranty of
19### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20### GNU General Public License for more details.
21###
22### You should have received a copy of the GNU General Public License
599c8f75 23### along with distorted-keys; if not, write to the Free Software Foundation,
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24### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
25
26set -e
27case "${KEYSLIB+t}" in t) ;; *) echo >&2 "$0: KEYSLIB unset"; exit 1 ;; esac
28. "$KEYSLIB"/keyfunc.sh
29
30defhelp <<HELP
ae0eb898 31[-i INST] RECOV KEEPER
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32Reveal a share of a recovery key distributed among keepers.
33
34If enough shares have been revealed, reconstruct the recovery private key.
d516ebd0 35The keeper nub is read from stdin.
53263601 36HELP
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37
38## Parse the command line.
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39inst=current
40while getopts "i:" opt; do
41 case "$opt" in
42 i) inst=$OPTARG ;;
43 *) usage_err ;;
44 esac
45done
46shift $(( $OPTIND - 1 ))
d516ebd0 47case $# in 2) ;; *) usage_err ;; esac
53263601 48recov=$1 keeper=$2; shift 2
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49checkword "recovery instance" "$inst"
50checkword "recovery key" "$recov"
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51checkword "keeper set label" "$keeper"
52
c47f2aba 53## Check that this is a sensible thing to do.
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54kdir=$KEYS/keeper/$keeper
55if [ ! -f $kdir/meta ]; then
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56 echo >&2 "$quis: unknown keeper set \`$keeper'"
57 exit 1
58fi
ae0eb898 59if [ ! -l $KEYS/recov/$recov/current ]; then
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60 echo >&2 "$quis: unknown recovery key \`$recov'"
61 exit 1
62fi
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63rdir=$KEYS/recov/$recov/$inst
64if [ ! -f $rdir/$keeper.param ]; then
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65 echo >&2 "$quis: recovery key \`$recov' not kept by keeper set \`$keeper'"
66 exit 1
67fi
68
53263601 69## Grab the key, because we'll need to read it several times.
c47f2aba 70mktmp
d516ebd0 71cat >$tmp/secret
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72
73## Read the threshold from the recovery metadata.
ae0eb898 74t=$(sharethresh $rdir/$keeper.param)
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75
76## Find out which keeper index it corresponds to.
ae0eb898 77read n hunoz <$kdir/meta
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78i=0
79foundp=nil
80while [ $i -lt $n ]; do
ae0eb898 81 c_sysprepare $kdir/$i
c47f2aba 82 nubbin=$(nubid <$tmp/secret)
ae0eb898 83 nubid=$(cat $kdir/$i/nubid)
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84 case "$nubbin" in "$nubid") foundp=t; break ;; esac
85 i=$(( $i + 1 ))
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86done
87case $foundp in
c47f2aba 88 nil) echo >&2 "$quis: nub doesn't match keeper \`$keeper'"; exit 1 ;;
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89esac
90
91## Establish the recovery staging area. See whether we've done enough
92## already.
c47f2aba 93reqsafe
ae0eb898 94tag=$recov.$inst
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95mkdir -p -m700 $SAFE/keys.reveal
96reveal=$SAFE/keys.reveal/$tag
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97if [ ! -d $reveal ]; then mkdir -m700 $reveal; fi
98cd $reveal
c47f2aba 99if [ -f nub ]; then
ae0eb898 100 echo >&2 "$quis: recovery key \`$recov/$inst' already revealed"
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101 exit 1
102fi
103
104## Decrypt the share.
599c8f75 105umask 077
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106if [ -f $keeper.$i.share ]; then
107 echo >&2 "$quis: share $i already revealed"
108else
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109 c_sysdecrypt $kdir/$i $tmp/secret \
110 <$rdir/$keeper.$i.share \
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111 >$keeper.$i.new
112 mv $keeper.$i.new $keeper.$i.share
113fi
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114
115## See if there's enough for a recovery.
116n=0
c47f2aba 117for j in $keeper.*.share; do if [ -f "$j" ]; then n=$(( $n + 1 )); fi; done
53263601 118if [ $n -lt $t ]; then
c47f2aba 119 echo >&2 "$quis: share $i revealed; $(( $t - $n )) more required"
53263601 120else
ae0eb898 121 cat $rdir/$keeper.param $keeper.*.share >$keeper.shares
5c30c6e6 122 $bindir/shamir recover <$keeper.shares >nub.new
ae0eb898 123 c_sysprepare $rdir/store
c47f2aba 124 nubbin=$(nubid <nub.new)
ae0eb898 125 nubid=$(cat $rdir/store/nubid)
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126 case "$nubbin" in
127 "$nubid") ;;
53263601 128 *)
c47f2aba 129 echo >&2 "$quis: recovered nub doesn't match stored hash"
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130 exit 1
131 ;;
132 esac
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133 mv nub.new nub
134 rm -f $keeper.*
ae0eb898 135 echo >&2 "$quis: recovery key \`$recov/$inst' revealed"
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136fi
137
138###----- That's all, folks --------------------------------------------------