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#!/bin/sh -e
# Copyright (c) 2021, la-ninpre
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
# ---------------------------------------------------------------------- #
#
# small script to backup secret gpg keys using paperkey and qrencode.
#
# basic usage:
#
# $ paperbackup -u user@email.com
#
# by default exports minimized public key and paperkeyed secret key
# to qr-encoded images, which then are combined into one image for
# easy printing.
#
# dependencies:
# - gpg (obviously)
# - paperkey
# - qrencode
# - imagemagick (optional, use -n to disable montage)
usage() {
echo "usage: ${0##*/} [OPTIONS]"
echo
echo "options:"
echo " -u, --uid {UID}"
echo " gpg keyid or uid (this is mandatory)"
echo " -l, --level {L,M,Q,H}"
echo " qrencode correction level"
echo " -t, --term"
echo " output to terminal instead of png image"
echo " -n, --nomontage"
echo " disable composing qrcodes to one image"
echo " -h, --help"
echo " print usage information"
echo
}
check_uid() {
[ -z "$1" ] && echo "uid could not be empty" && exit 1
if ! gpg -K "$1" >/dev/null
then
exit 1
fi
PB_UID="$1"
}
check_corr_lvl() {
case "$1" in
l|L|m|M|q|Q|h|H)
PB_CORR_LVL="$1"
;;
*)
echo "correction level should be one of L,M,Q,H"
usage
exit 1
;;
esac
}
qr_encode() {
PB_QRENCODE_FLAGS="-8 -l $PB_CORR_LVL -t $PB_TYPE"
case "$PB_TYPE" in
png)
PB_QRENCODE_FLAGS="$PB_QRENCODE_FLAGS -o $1"
;;
UTF8)
;;
*)
exit 1
;;
esac
# i don't know if it is safe to do so, but it's very convenient
# shellcheck disable=SC2086
qrencode $PB_QRENCODE_FLAGS
}
get_pubkey() {
[ -n "$1" ] && gpg --export --export-options export-minimal "$1" \
| qr_encode "$1-pubkey.png"
}
get_seckey() {
[ -n "$1" ] && gpg --export-secret-key "$1" \
| paperkey --output-type raw | qr_encode "$1-seckey.png"
}
montage_keys() {
montage \
-pointsize 18 \
-title "\nsecret key backup for $PB_UID\n$PB_DATE" \
-label pubkey "$PB_UID-pubkey.png" \
-label seckey "$PB_UID-seckey.png" \
-mode concatenate \
"$PB_UID-keys.png"
rm -f "$PB_UID-pubkey.png" "$PB_UID-seckey.png"
}
main() {
PB_TYPE="png"
PB_CORR_LVL="H"
PB_DATE=$(date "+%F %T")
PB_MONTAGE=1
while [ -n "$1" ]
do
case "$1" in
--uid|-u)
shift
check_uid "$1"
;;
--level|-l)
shift
check_corr_lvl "$1"
;;
--term|-t)
PB_TYPE="UTF8"
;;
--nomontage|-n)
PB_MONTAGE=0
;;
--help|-h)
echo "backup secret gpg key using paperkey and qrencode"
echo
usage
exit
;;
*)
usage
exit 1
;;
esac
shift
done
[ -z "$PB_UID" ] && echo "please specify uid or keyid" && exit 1;
get_pubkey "$PB_UID" && get_seckey "$PB_UID"
[ "$PB_TYPE" = "png" ] \
&& [ "$PB_MONTAGE" -eq 1 ] \
&& montage_keys
exit 0
}
main "$@"
|
