#!/bin/bash
#
# .---.                  .              .
# |                      |              |
# |--- .--. .-.  .-.  .-.|  .-. .--.--. |.-.  .-. .--.  .-.
# |    |   (.-' (.-' (   | (   )|  |  | |   )(   )|  | (.-'
# '    '     --'  --'  -' -  -' '  '   -' -'   -' '   -  --'
#
#                    Freedom in the Cloud
#
# Encryption key related functions

# License
# =======
#
# Copyright (C) 2015-2016 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 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/>.

function reconstruct_key {
    if [ ! -d /home/$MY_USERNAME/.gnupg_fragments ]; then
        return
    fi
    cd /home/$MY_USERNAME/.gnupg_fragments
    no_of_shares=$(ls -afq keyshare.asc.* | wc -l)
    if (( no_of_shares < 4 )); then
        dialog --title $"Recover Encryption Keys" --msgbox $'Not enough fragments to reconstruct the key' 6 70
        exit 7348
    fi
    apt-get -yq install libgfshare-bin gnupg
    gfcombine /home/$MY_USERNAME/.gnupg_fragments/keyshare*
    if [ ! "$?" = "0" ]; then
        dialog --title $"Recover Encryption Keys" --msgbox $'Unable to reconstruct the key' 6 70
        exit 7348
    fi

    KEYS_FILE=/home/$MY_USERNAME/.gnupg_fragments/keyshare.asc
    if [ ! -f $KEYS_FILE ]; then
        dialog --title $"Recover Encryption Keys" --msgbox $'Unable to reconstruct the key' 6 70
    fi

    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 9654
    fi
    shred -zu $KEYS_FILE

    dialog --title $"Recover Encryption Keys" --msgbox $'Key has been reconstructed' 6 70
}

function interactive_gpg_from_usb {
    dialog --title $"Recover Encryption Keys" \
           --msgbox $'Plug in a USB keydrive containing a copy of your full key or key fragment' 6 70

    HOME_DIR=/home/$MY_USERNAME
    GPG_LOADING="yes"
    SSH_IMPORTED="no"
    GPG_CTR=0
    while [[ $GPG_LOADING == "yes" ]]
    do
        detect_usb_drive

        if [ ! -b $USB_DRIVE ]; then
            if (( GPG_CTR > 0 )); then
                reconstruct_key
                return 0
            fi
            dialog --title $"Recover Encryption Keys" --msgbox $'No USB drive found' 6 30
            exit 739836
        fi

        GPG_USB_MOUNT='/mnt/usb'
        umount -f $GPG_USB_MOUNT
        if [ ! -d $GPG_USB_MOUNT ]; then
            mkdir -p $GPG_USB_MOUNT
        fi

        if [ -f /dev/mapper/encrypted_usb ]; then
            rm -rf /dev/mapper/encrypted_usb
        fi
        cryptsetup luksClose encrypted_usb
        cryptsetup luksOpen $USB_DRIVE encrypted_usb
        if [ "$?" = "0" ]; then
            USB_DRIVE=/dev/mapper/encrypted_usb
        fi
        mount $USB_DRIVE $GPG_USB_MOUNT
        if [ ! "$?" = "0" ]; then
            if (( GPG_CTR > 0 )); then
                rm -rf $GPG_USB_MOUNT
                reconstruct_key
                return 0
            fi
            dialog --title $"Recover Encryption Keys" \
                   --msgbox $"There was a problem mounting the USB drive to $GPG_USB_MOUNT" 6 70
            rm -rf $GPG_USB_MOUNT
            exit 74393
        fi

        if [ ! -d $GPG_USB_MOUNT/.gnupg ]; then
            if [ ! -d $GPG_USB_MOUNT/.gnupg_fragments ]; then
                if (( GPG_CTR > 0 )); then
                    umount -f $GPG_USB_MOUNT
                    rm -rf $GPG_USB_MOUNT
                    reconstruct_key
                    return 0
                fi
                dialog --title $"Recover Encryption Keys" \
                       --msgbox $"The directory $GPG_USB_MOUNT/.gnupg or $GPG_USB_MOUNT/.gnupg_fragments was not found" 6 70
                umount -f $GPG_USB_MOUNT
                rm -rf $GPG_USB_MOUNT
                exit 723814
            fi
        fi

        if [ -d $GPG_USB_MOUNT/.gnupg ]; then
            if [ ! -d $HOME_DIR/.gnupg ]; then
                mkdir $HOME_DIR/.gnupg
            fi
            cp -r $GPG_USB_MOUNT/.gnupg/* $HOME_DIR/.gnupg
            GPG_LOADING="no"
            dialog --title $"Recover Encryption Keys" \
                   --msgbox $"GPG Keyring loaded to $HOME_DIR" 6 70
        else
            if [ ! -d $HOME_DIR/.gnupg_fragments ]; then
                mkdir $HOME_DIR/.gnupg_fragments
            fi
            cp -r $GPG_USB_MOUNT/.gnupg_fragments/* $HOME_DIR/.gnupg_fragments
        fi

        if [[ $SSH_IMPORTED == "no" ]]; then
            if [ -d $GPG_USB_MOUNT/.ssh ]; then
                if [ ! -d $HOME_DIR/.ssh ]; then
                    mkdir $HOME_DIR/.ssh
                fi
                cp $GPG_USB_MOUNT/.ssh/* $HOME_DIR/.ssh
                dialog --title $"Recover Encryption Keys" \
                       --msgbox $"ssh keys imported" 6 70
                SSH_IMPORTED="yes"
            fi
        fi

        umount -f $GPG_USB_MOUNT
        rm -rf $GPG_USB_MOUNT
        if [[ $GPG_LOADING == "yes" ]]; then
            dialog --title $"Recover Encryption Keys" \
                   --msgbox $"Now remove the USB drive. Insert the next drive containing a key fragment, or select Ok to finish" 6 70
        fi
        GPG_CTR=$((GPG_CTR + 1))
    done
}

# NOTE: deliberately there is no "exit 0"