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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 | ### | |
10 | ### This program is free software; you can redistribute it and/or modify | |
11 | ### it under the terms of the GNU General Public License as published by | |
12 | ### the Free Software Foundation; either version 2 of the License, or | |
13 | ### (at your option) any later version. | |
14 | ### | |
15 | ### This program is distributed in the hope that it will be useful, | |
16 | ### but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ### GNU General Public License for more details. | |
19 | ### | |
20 | ### You should have received a copy of the GNU General Public License | |
21 | ### along with this program; if not, write to the Free Software Foundation, | |
22 | ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
23 | ||
24 | set -e | |
25 | case "${KEYSLIB+t}" in t) ;; *) echo >&2 "$0: KEYSLIB unset"; exit 1 ;; esac | |
26 | . "$KEYSLIB"/keyfunc.sh | |
27 | ||
28 | defhelp <<HELP | |
29 | RECOV KEEPER [KEY] | |
30 | Reveal a share of a recovery key distributed among keepers. | |
31 | ||
32 | If enough shares have been revealed, reconstruct the recovery private key. | |
33 | The key is read from KEY, or stdin if KEY is omitted or \`-'. | |
34 | HELP | |
35 | dohelp | |
36 | ||
37 | ## Parse the command line. | |
38 | case $# in | |
39 | 2) if [ -t 0 ]; then echo >&2 "$quis: stdin is a terminal"; exit 1; fi ;; | |
40 | 3) ;; | |
41 | *) echo >&2 "$usage"; exit 1 ;; | |
42 | esac | |
43 | recov=$1 keeper=$2; shift 2 | |
44 | case "$recov" in | |
45 | *[!-0-9a-zA-Z_!%@+=/]* | */ | /* | \ | |
46 | *[!-0-9a-zA-Z_!%@+=]*/* | */*[!-0-9a-zA-Z_!%@+=]*) | |
47 | echo >&2 "$quis: bad recovery key label \`$recov'" | |
48 | exit 1 | |
49 | ;; | |
50 | */*) | |
51 | ;; | |
52 | *) | |
53 | recov=$recov/current | |
54 | esac | |
55 | checkword "keeper set label" "$keeper" | |
56 | ||
57 | ## Grab the key, because we'll need to read it several times. | |
58 | tmp=$(mktmp); cleanup rmtmp | |
59 | secret=$(cat "$@") | |
60 | pub=$(ec_public /dev/stdin <<EOF | |
61 | $secret | |
62 | EOF | |
63 | ) | |
64 | ||
65 | ## Read the threshold from the recovery metadata. | |
66 | read param <$KEYS/recov/$recov/$keeper.param | |
67 | case "$param" in | |
68 | shamir-params:*) ;; | |
69 | *) | |
70 | echo >&2 "$quis: secret sharing parameter file damaged (wrong header)" | |
71 | exit 1 | |
72 | ;; | |
73 | esac | |
74 | t=";${param#*:}" | |
75 | case "$t" in | |
76 | *";t="*) ;; | |
77 | *) | |
78 | echo >&2 "$quis: secret sharing parameter file damaged (missing t)" | |
79 | exit 1 | |
80 | ;; | |
81 | esac | |
82 | t=${t#*;t=} | |
83 | t=${t%%;*} | |
84 | ||
85 | ## Find out which keeper index it corresponds to. | |
86 | read n hunoz <$KEYS/keeper/$keeper/meta | |
87 | i=0 | |
88 | foundp=nil | |
89 | while [ $i -lt $n ]; do | |
90 | read cand <$KEYS/keeper/$keeper/$i.pub | |
91 | case "$pub" in "$cand") foundp=t; break ;; esac | |
92 | i=$(( i + 1 )) | |
93 | done | |
94 | case $foundp in | |
95 | nil) echo >&2 "$quis: key doesn't match keeper \`$keeper'"; exit 1 ;; | |
96 | esac | |
97 | ||
98 | ## Establish the recovery staging area. See whether we've done enough | |
99 | ## already. | |
100 | mem=$(userv root claim-mem-dir) | |
101 | tag=$(echo $recov | tr / .) | |
102 | if [ -d $mem/keys.reveal.$tag ]; then | |
103 | echo >&2 "$quis: secret $recov already revealed" | |
104 | exit 1 | |
105 | fi | |
106 | reveal=$mem/keys.reveal.$tag.$keeper | |
107 | if [ ! -d $reveal ]; then mkdir -m700 $reveal; fi | |
108 | cd $reveal | |
109 | if [ -f share.$i ]; then | |
110 | echo >&2 "$quis: share $i already revealed" | |
111 | exit 1 | |
112 | fi | |
113 | ||
114 | ## Decrypt the share. | |
115 | ec_decrypt /dev/stdin \ | |
116 | -i$KEYS/recov/$recov/$keeper.$i.share \ | |
117 | -oshare.$i.new <<EOF | |
118 | $secret | |
119 | EOF | |
120 | mv share.$i.new share.$i | |
121 | ||
122 | ## See if there's enough for a recovery. | |
123 | n=0 | |
124 | for j in share.*; do if [ -f "$j" ]; then n=$(( n + 1 )); fi; done | |
125 | if [ $n -lt $t ]; then | |
126 | echo >&2 "$quis: share $i revealed; $(( t - n )) more required" | |
127 | else | |
128 | cat $KEYS/recov/$recov/$keeper.param share.* | shamir recover >secret | |
129 | pubx=$(ec_public secret) | |
130 | puby=$(cat $KEYS/recov/$recov/pub) | |
131 | case "$pubx" in | |
132 | "$puby") ;; | |
133 | *) | |
134 | echo >&2 "quis: recovered secret key doesn't match public key" | |
135 | exit 1 | |
136 | ;; | |
137 | esac | |
138 | cd .. | |
139 | mv keys.reveal.$tag.$keeper keys.reveal.$tag | |
140 | echo >&2 "$quis: secret $recov revealed" | |
141 | fi | |
142 | ||
143 | ###----- That's all, folks -------------------------------------------------- |