#!/bin/bash
#
# .---.                  .              .
# |                      |              |
# |--- .--. .-.  .-.  .-.|  .-. .--.--. |.-.  .-. .--.  .-.
# |    |   (.-' (.-' (   | (   )|  |  | |   )(   )|  | (.-'
# '    '     --'  --'  -' -  -' '  '   -' -'   -' '   -  --'
#
#                    Freedom in the Cloud
#
# Makes a USB drive containing a gpg key fragment
#
# License
# =======
#
# Copyright (C) 2015-2017 Bob Mottram <bob@freedombone.net>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

PROJECT_NAME='freedombone'

export TEXTDOMAIN=${PROJECT_NAME}-keydrive
export TEXTDOMAINDIR="/usr/share/locale"

USB_DRIVE=/dev/sdb1
USB_MOUNT=/mnt/usb
KEY_FRAGMENTS=3
FRAGMENTS_DIR=$USB_MOUNT/.gnupg_fragments
MY_USERNAME=$USER
MASTER_DRIVE="no"
FORMAT="no"

function show_help {
    echo ''
    echo $"${PROJECT_NAME}-keydrive -u [username] -d [device, eg. sdb] --master [yes/no] -n [no of fragments] --format [yes/no]"
    echo ''
    exit 0
}

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

    case $key in
        -h|--help)
            show_help
            ;;
        -u|--user)
            shift
            MY_USERNAME="$1"
            ;;
        -d|--dev)
            shift
            if [[ "${1}" != '/dev/'* ]]; then
                USB_DRIVE=/dev/${1}1
            else
                USB_DRIVE=${1}
            fi
            ;;
        -m|--master)
            shift
            MASTER_DRIVE="$1"
            ;;
        -n|--fragments)
            shift
            KEY_FRAGMENTS=$1
            ;;
        -f|--format)
            shift
            FORMAT="yes"
            ;;
        *)
            # unknown option
            ;;
    esac
    shift
done

if [ ! $MY_USERNAME ]; then
    echo $'No username given'
    exit 69350
fi

if [ ! -d /home/$MY_USERNAME ]; then
    echo $"Home directory for $MY_USERNAME not found. This user may not exist on the system"
    exit 72378
fi

if [ ! -b $USB_DRIVE ]; then
    echo $'Please attach a USB drive'
    exit 65743
fi

umount -f $USB_MOUNT
if [ ! -d $USB_MOUNT ]; then
    mkdir $USB_MOUNT
fi
if [ -f /dev/mapper/encrypted_usb ]; then
    rm -rf /dev/mapper/encrypted_usb
fi
cryptsetup luksClose encrypted_usb

# optionally format the drive
if [[ $FORMAT == "yes" ]]; then
    ${PROJECT_NAME}-format ${USB_DRIVE::-1}
    if [ ! "$?" = "0" ]; then
        exit 36823
    fi
fi

cryptsetup luksOpen $USB_DRIVE encrypted_usb
if [ "$?" = "0" ]; then
    USB_DRIVE=/dev/mapper/encrypted_usb
fi
mount $USB_DRIVE $USB_MOUNT
if [ ! "$?" = "0" ]; then
    echo $"There was a problem mounting the USB drive to $USB_MOUNT"
    rm -rf $USB_MOUNT
    exit 78543
fi

# optionally create a master drive which contains the full GPG keyring
if [[ $MASTER_DRIVE == "yes" || $MASTER_DRIVE == "y" || $MASTER_DRIVE == "1" ]]; then
    if [ ! -d /home/$MY_USERNAME/.gnupg ]; then
        echo $"No .gnupg directory was found for $MY_USERNAME"
        umount -f $USB_MOUNT
        rm -rf $USB_MOUNT
        exit 73025
    fi

    # export the gpg key and backup key as text
    # so that it may be imported at the beginning of new installs
    GPG_TTY=$(tty)
    export GPG_TTY

    USER_EMAIL_ADDRESS=$MY_USERNAME@$HOSTNAME
    GPG_ID=$(su -m root -c "gpg --list-keys $USER_EMAIL_ADDRESS | sed -n '2p' | sed 's/^[ \t]*//'" - $MY_USERNAME)
    GPG_BACKUP_ID=$(su -m root -c "gpg --list-keys \"(backup key)\" | sed -n '2p' | sed 's/^[ \t]*//'" - $MY_USERNAME)

    gpgerrstr=$'error'
    gpgkey=$(gpg --homedir=/home/$MY_USERNAME/.gnupg --armor --export $GPG_ID)
    if [[ "$gpgkey" == *"$gpgerrstr"* ]]; then
        echo $'Problem exporting public gpg key'
        echo "$gpgkey"
        exit 735282
    fi
    echo ''
    echo $'Enter your gpg private key passphrase:'
    gpgprivkey=$(gpg --homedir=/home/$MY_USERNAME/.gnupg --armor --export-secret-key $GPG_ID)
    if [[ "$gpgprivkey" == *"$gpgerrstr"* ]]; then
        echo $'Problem exporting private gpg key'
        echo "$gpgprivkey"
        gpgprivkey=
        exit 629362
    fi

    # Dummy password to get around not being able to create a key without passphrase
    BACKUP_DUMMY_PASSWORD='backup'

    backupgpgkey=$(gpg --homedir=/home/$MY_USERNAME/.gnupg --armor --export $GPG_BACKUP_ID)
    if [[ "$backupgpgkey" == *"$gpgerrstr"* ]]; then
        echo $'Problem exporting public gpg backup key'
        echo "$backupgpgkey"
        exit 735282
    fi
    backupgpgprivkey=$(echo "$BACKUP_DUMMY_PASSWORD" | gpg --batch --passphrase-fd 0 --homedir=/home/$MY_USERNAME/.gnupg --armor --export-secret-key $GPG_BACKUP_ID)
    if [[ "$backupgpgprivkey" == *"$gpgerrstr"* ]]; then
        echo $'Problem exporting private gpg backup key'
        echo "$backupgpgprivkey"
        backupgpgprivkey=
        exit 629362
    fi

    echo "$gpgkey" > $USB_MOUNT/.mastergpgkey
    echo "$gpgprivkey" >> $USB_MOUNT/.mastergpgkey
    echo "$backupgpgkey" > $USB_MOUNT/.backupgpgkey
    echo "$backupgpgprivkey" >> $USB_MOUNT/.backupgpgkey

    cp -rf /home/$MY_USERNAME/.gnupg $USB_MOUNT

    if [ -d /etc/letsencrypt ]; then
        cp -rf /etc/letsencrypt $USB_MOUNT
        echo $"LetsEncrypt keys copied to $USB_DRIVE"
    fi
    if [ -d $USB_MOUNT/.gnupg ]; then
        echo $"GPG Keyring copied to $USB_DRIVE. You may now remove the drive."
    else
        echo $"Unable to copy gpg keyring to $USB_DRIVE"
    fi
    umount -f $USB_MOUNT
    rm -rf $USB_MOUNT
    exit 0
fi

# Don't use the USB drive if it already contains a full keyring
if [ -d $USB_MOUNT/.gnupg ]; then
    echo $'A full GPG keyring already exists on the USB drive.'
    echo $'Either reformat the USB drive or use a different drive.'
    umount -f $USB_MOUNT
    rm -rf $USB_MOUNT
    exit 3392
fi

# Append the username as a subdirectory.
# This has a down side in that it does identify a given fragment
# as belonging to a given user, but has the convenience upside
# of being able to carry key fragments for multiple friends on
# the same USB drive
FRAGMENTS_DIR=$FRAGMENTS_DIR/$MY_USERNAME

# make a directory to contain the fragments
if [ ! -d $FRAGMENTS_DIR ]; then
    mkdir -p $FRAGMENTS_DIR
    echo $"Made directory $FRAGMENTS_DIR"
fi
if [ ! -d $FRAGMENTS_DIR ]; then
    echo $"There was a problem making the directory $FRAGMENTS_DIR"
    umount -f $USB_MOUNT
    rm -rf $USB_MOUNT
    exit 6843
fi

cd $FRAGMENTS_DIR
no_of_usb_shares=$(ls -afq keyshare.asc.* | wc -l)
if [ ! "$?" = "0" ]; then
    no_of_usb_shares=0
fi
if (( no_of_usb_shares > 0 )); then
    echo $"A key fragment already exists on the drive for the user $MY_USERNAME"
    cd ~/
    umount -f $USB_MOUNT
    rm -rf $USB_MOUNT
    exit 58945
fi

# copy a random fragment to the drive
LOCAL_FRAGMENTS_DIR=/home/$MY_USERNAME/.gnupg_fragments

if [ ! -d $LOCAL_FRAGMENTS_DIR ]; then
    ${PROJECT_NAME}-splitkey -u $MY_USERNAME -n $KEY_FRAGMENTS
fi

cd $LOCAL_FRAGMENTS_DIR
no_of_local_shares=$(ls -afq keyshare.asc.* | wc -l)
if [ ! "$?" = "0" ]; then
    no_of_local_shares=0
fi
if (( no_of_local_shares < 3 )); then
    ${PROJECT_NAME}-splitkey -u $MY_USERNAME -n $KEY_FRAGMENTS
    cd $LOCAL_FRAGMENTS_DIR
    no_of_local_shares=$(ls -afq keyshare.asc.* | wc -l)
    if [ ! "$?" = "0" ]; then
        no_of_local_shares=0
    fi
fi

if (( no_of_local_shares < 3 )); then
    echo $"Not enough key fragments available ${no_of_local_shares}"
    cd ~/
    umount -f $USB_MOUNT
    rm -rf $USB_MOUNT
    exit 63386
fi

share_files=($LOCAL_FRAGMENTS_DIR/keyshare.asc.*)
SHARE_FILENAME=${share_files[RANDOM % ${#share_files[@]}]}

cp -f $SHARE_FILENAME $FRAGMENTS_DIR
cd $FRAGMENTS_DIR
no_of_usb_shares=$(ls -afq keyshare.asc.* | wc -l)
echo $"Number of fragments on the drive: ${no_of_usb_shares}"
if (( no_of_usb_shares > 1 )); then
    echo $"Too many key fragments exist in $FRAGMENTS_DIR"
    ls $FRAGMENTS_DIR
    cd ~/
    umount -f $USB_MOUNT
    rm -rf $USB_MOUNT
    exit 54292
fi
if (( no_of_usb_shares <= 0 )); then
    echo $"There was a problem copying the key fragment to $USB_DRIVE"
    echo $"Files found: ${no_of_usb_shares}"
    ls $FRAGMENTS_DIR
    cd ~/
    umount -f $USB_MOUNT
    rm -rf $USB_MOUNT
    exit 54292
fi

cd ~/
umount -f $USB_MOUNT
rm -rf $USB_MOUNT
echo $"Key fragment copied to $USB_DRIVE. You may now remove the drive."

exit 0