#! /bin/sh
###
### Generate a new recovery key and split it among keepers
###
### (c) 2011 Mark Wooding
###

###----- Licensing notice ---------------------------------------------------
###
### This file is part of the distorted.org.uk key management suite.
###
### distorted-keys is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### distorted-keys is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with distorted-keys; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

set -e
case "${KEYSLIB+t}" in t) ;; *) echo >&2 "$0: KEYSLIB unset"; exit 1 ;; esac
. "$KEYSLIB"/keyfunc.sh

defhelp <<HELP
RECOV [KEEPER:K ...]
Generate a new recovery secret, and split it among the available keepers.

The new secret will be called RECOV.  For each KEEPER set, the private key
wil be split into shares, and encrypted with the KEEPER's public keys; any K
of these shares can be used to reveal the original key.

If there is already a recovery key called RECOV then it will be rolled over.
The previous key must already be revealed.  If KEEPERs are listed, these
replace the existing keeper sets; otherwise the same keepers as before are
used.

If there is not a recovery key called RECOV then at least one keeper set must
be specified.
HELP
dohelp

## Parse the command line.
case $# in 0) echo >&2 "$usage"; exit 1 ;; esac
recov=$1; shift
checkword "recovery key label" "$recov"
for k in "$@"; do
  case "$k" in
    *:*) ;;
    *) echo >&2 "$quis: bad keeper spec \`$k'"; exit 1 ;;
  esac
  keeper=${k%:*} t=${k#*:}
  checkword "keeper set label" "$keeper"
  checknumber "keeper quorum" "$t"
done

## Establish the keeper parameters.
rdir=$KEYS/recov/$recov
if [ ! -d $rdir ]; then mkdir -m755 -p $rdir; fi
case $# in
  0)
    kparam=$rdir/keepers
    ;;
  *)
    for k in "$@"; do
      keeper=${k%:*} t=${k#*:}
      echo $keeper $t
    done >$rdir/keepers.new
    kparam=$rdir/keepers.new
    ;;
esac
if [ ! -f $kparam ]; then echo >&2 "$quis: no keepers specified"; exit 1; fi

## Make the new key and issue the shares.
tmp=$(mktmp); cleanup rmtmp
rm -rf $rdir/new
mkdir -m755 $rdir/new
cd $tmp
ec_keygen secret $rdir/new/pub
while read keeper k; do
  read n hunoz <$KEYS/keeper/$keeper/meta
  shamir issue $k/$n secret | {
    read param
    echo "$param" >$rdir/new/$keeper.param
    i=0
    while read share; do
      echo $share |
	ec_encrypt $KEYS/keeper/$keeper/$i.pub -o$rdir/new/$keeper.$i.share
      i=$(( i + 1 ))
    done
  }
done <$kparam
rm -f secret

## If there's an existing instance of this key, transfer the recovery blobs.
if [ ! -d $rdir/current ]; then
  seq=0
else
  seq=$(readlink $rdir/current)
  mem=$(userv root claim-mem-dir </dev/null)
  reveal=$mem/keys.reveal/$recov.current/secret
  if [ ! -f $reveal ]; then
    echo >&2 "$quis: current $recov key not revealed"
    exit 1
  fi

  find $rdir/current/ -type f -name '*.recov' -print | while read name; do
    name=${name#$rdir/current/}
    case "$name" in */*) mkdir -p -m755 $rdir/new/${name%/*} ;; esac
    ec_decrypt $reveal -i$rdir/current/$name |
      ec_encrypt $rdir/new/pub -o$rdir/new/$name
  done
  rm -r $mem/keys.reveal/$recov.current
fi

## Tidy up and commit.  Repointing the symlink is grim because, according to
## POSIX rules, `mv foo bar' should rename `foo' to `bar/foo' is `bar' is a
## symlink to a directory -- and there's no way of turning this behaviour
## off.  The subterfuge here is due to Colin Watson.
cd $rdir
while [ -d $seq ]; do seq=$(( seq + 1 )); done
case $kparam in *.new) mv keepers.new keepers ;; esac
rm -f next
ln -s $seq next
mv new $seq
mkdir hack; mv next hack/current; mv hack/current .; rmdir hack

###----- That's all, folks --------------------------------------------------