83 lines
2.1 KiB
Bash
83 lines
2.1 KiB
Bash
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#!/bin/bash
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#####
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#
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# Author: Kevin Douglas <douglk@gmail.com>
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#
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# Simple command line script to backup ascii armor gpg keys to paper. You can
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# use the following commands to export your keys in ascii armor format:
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#
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# gpg --armor --export > pgp-public-keys.asc
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# gpg --armor --export-secret-keys > pgp-private-keys.asc
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# gpg --armor --gen-revoke [your key ID] > pgp-revocation.asc
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#
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# These can then be used to restore your keys if necessary.
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#
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# This script will allow you to convert the above ascii armor keys into a
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# printable QR code for long-term archival.
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#
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# This script depends on the following libraries/applications:
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#
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# libqrencode (http://fukuchi.org/works/qrencode/)
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#
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# If you need to backup or restore binary keys, see this link to get started:
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#
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# https://gist.github.com/joostrijneveld/59ab61faa21910c8434c#file-gpg2qrcodes-sh
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#
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#####
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# Maximum chuck size to send to the QR encoder. QR version 40 supports
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# 2,953 bytes of storage.
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file_split_size=2800
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# Prefix string for the PNG images that are produced
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image_prefix="QR"
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# Argument/usage check
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if [ $# -ne 1 ]; then
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echo "usage: `basename ${0}` <ascii armor key file>"
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exit 1
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fi
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asc_key=${1}
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if [ ! -f ${asc_key} ]; then
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echo "key file not found: ${asc_key}"
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exit 1
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fi
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# Create a temp file to use as a pattern for splitting the input key file.
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# This helps protect against file collisions in the current directory.
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export TMPDIR=""
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tmp_file=$(mktemp keyparts.XXXXXX)
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if [ $? -ne 0 ]; then
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echo "failed to create temporary file"
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exit 1
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fi
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# Split the key file into usable chunks that the QR encoder can consume
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split -b ${file_split_size} ${asc_key} "${tmp_file}."
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# For each chunk, encode it into a qc image
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index=1
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for file in ${tmp_file}.*; do
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img="${image_prefix}${index}.png"
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echo "generating ${img}"
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cat ${file} | qrencode -o ${img}
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if [ $? -ne 0 ]; then
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echo "failed to encode image"
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exit 2
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fi
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index=$((index+1))
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done
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# Find the correct secure deletion utility (srm on Mac, shred on Linux)
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sec_del="srm"
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which ${sec_del} 2>&1 1>/dev/null
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if [ $? -ne 0 ]; then
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sec_del="shred --remove"
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fi
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# Securely clean up temporary files
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${sec_del} ${tmp_file}
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${sec_del} ${tmp_file}.*
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