PaperKey with Bash

paperkey.sh

#!/bin/bash
# Hello HN!
# to read back the chunks, use zbarcam.

if [ "$#" -ne "1" ]; then
    echo "Please specify the private key file (should be in PEM format)"
    exit 1
fi

private_key=$1

rm private_key_*.txt
rm private_key_split_*.txt.png
rm page_*.ps


# split key in 260 byte chunks, above that zbarcam has difficulty reading the Qr codes
split -a 2 --additional-suffix=.txt -b 256 -d "$private_key" private_key_split_

# encode in qr code
for i in private_key_split_*.txt
do
    echo "Encoding $1 in $i.png"
    qrencode -l H -o "$i.png" < "$i"
done

# Do a 4x4 montage of pages
echo "Printing all images in ps files."
montage -label '%f' -tile 2x2 -geometry "100%x100%" ./*.png page_%d.ps

# shasum the key into a txt file
shasum=$(sha256sum "$private_key")
echo "sha256sum of $private_key is $shasum" > private_key_sha256.txt

# montage to print the actual base64 key with the SHA256 sum for last-resort
a2ps -4 -A fill private_key_split_*.txt private_key_sha256.txt -o page_clear.ps

nb_pages=$(find . -name "page_*.ps" | wc -l)
read -r -p "Do you want to print all $((nb_pages * 2 + 1)) pages [yN]" yesno

# prints all pages if user answers yes
if [ "$yesno" = "y" ]; then

    for i in *.ps
    do
        lp "$i"
    done

fi