#!/bin/bash
#
# .---.                  .              .
# |                      |              |
# |--- .--. .-.  .-.  .-.|  .-. .--.--. |.-.  .-. .--.  .-.
# |    |   (.-' (.-' (   | (   )|  |  | |   )(   )|  | (.-'
# '    '     --'  --'  -' -  -' '  '   -' -'   -' '   -  --'
#
#                    Freedom in the Cloud
#
# A script which recovers a user's gpg key from a number of fragments

# License
# =======
#
# Copyright (C) 2015 Bob Mottram <bob@robotics.uk.to>
#
# This program 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 3 of the License, or
# (at your option) any later version.
#
# This program 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 this program. If not, see <http://www.gnu.org/licenses/>.

function show_help {
    echo ''
    echo 'freedombone-recoverkey -u [username]'
    echo ''
    exit 0
}

while [[ $# > 1 ]]
do
key="$1"

case $key in
    -h|--help)
    show_help
    ;;
    -u|--user)
    shift
    MY_USERNAME="$1"
    ;;
    *)
    # unknown option
    ;;
esac
shift
done

if [ ! $MY_USERNAME ]; then
    show_help
fi
if [ ! -d /home/$MY_USERNAME ]; then
    echo "User $MY_USERNAME does not exist on the system"
    exit 7270
fi

if [ ! $MY_USERNAME ]; then
    echo 'No username given'
    exit 3578
fi
if [ ! -d /home/$MY_USERNAME ]; then
    echo "User $MY_USERNAME does not exist on the system"
    exit 7270
fi
FRAGMENTS_DIR=/home/$MY_USERNAME/.gnupg_fragments
if [ ! -d $FRAGMENTS_DIR ]; then
    echo 'No fragments have been recovered, so the key cannot be recovered'
    exit 7483
fi

# join the fragments
if [ ! -d /home/$MY_USERNAME/.tempgnupg ]; then
    mkdir /home/$MY_USERNAME/.tempgnupg
fi
KEYS_FILE=/home/$MY_USERNAME/.tempgnupg/tempfile.asc
cat $FRAGMENTS_DIR/data* > $KEYS_FILE.gpg
if [ ! "$?" = "0" ]; then
    echo 'Unable to find key fragments'
    exit 8727
fi

# decrypt the file
cd /home/$MY_USERNAME/.tempgnupg
gpg -d $KEYS_FILE.gpg -o $KEYS_FILE
if [ ! "$?" = "0" ]; then
    echo 'Unable to decrypt data. This may mean that not enough fragments are available'
    exit 6283
fi
shred -zu $KEYS_FILE.gpg
if [ ! -f $KEYS_FILE ]; then
    echo 'Unable to find decrypted key file. This may mean that not enough fragments are available'
    exit 8358
fi
echo 'Key fragments decrypted'

# import the gpg key
su -c "gpg --allow-secret-key-import --import $KEYS_FILE" - $MY_USERNAME
if [ ! "$?" = "0" ]; then
    echo 'Unable to import gpg key'
    shred -zu $KEYS_FILE
    rm -rf /home/$MY_USERNAME/.tempgnupg
    exit 3682
fi
shred -zu $KEYS_FILE
chown -R $MY_USERNAME:$MY_USERNAME /home/$MY_USERNAME/.gnupg
chmod -R 600 /home/$MY_USERNAME/.gnupg
rm -rf /home/$MY_USERNAME/.tempgnupg

echo 'GPG key was recovered'

exit 0