| 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 -------------------------------------------------- |