Producing printable QR codes for persistent storage of GPG private keys

gpg2qr.sh

#!/bin/bash
# Main credit goes to joostrijneveld on github:
# Ref: https://gist.github.com/joostrijneveld/59ab61faa21910c8434c
# adopted to "I want to have a pdf with a textual AND QR key to directly
# print it and put it in the bank safe" needs by Jan Stuehler,
# 2015-10-05. 

if [ $# -lt 2 ]
then
   echo "Please specify [Key ID] and an arbitrary [Name]"
   exit 1
fi

TEMPDIR=gpg2qrtmp
KEYID=$1
KEYNAME=$2

echo "Creating temporary directory $TEMPDIR"
mkdir $TEMPDIR
echo "Changing directory to $TEMPDIR"
cd $TEMPDIR

# Ref: http://stackoverflow.com/a/677212
command -v gpg >/dev/null 2>&1 || { echo >&2 "I require gpg but it's not installed.  Aborting."; exit 1; }
command -v paperkey >/dev/null 2>&1 || { echo >&2 "I require paperkey but it's not installed.  Aborting."; exit 1; }
command -v qrencode >/dev/null 2>&1 || { echo >&2 "I require qrencode but it's not installed.  Aborting."; exit 1; }
command -v convert >/dev/null 2>&1 || { echo >&2 "I require convert (ImageMagick) but it's not installed.  Aborting."; exit 1; }
command -v zbarimg >/dev/null 2>&1 || { echo >&2 "I require zbarimg (zbar) but it's not installed.  Aborting."; exit 1; }
command -v a2ps >/dev/null 2>&1 || { echo >&2 "I require a2ps but it's not installed.  Aborting."; exit 1; }
command -v ps2pdf >/dev/null 2>&1 || { echo >&2 "I require ps2pdf but it's not installed.  Aborting."; exit 1; }


### EXPORT KEY
gpg --export-secret-key $KEYID | paperkey --output-type raw | base64 > $KEYNAME

### GENERATE TITLE PAGE
echo "$KEYNAME:\n" > titlepage.txt
cat $KEYNAME >> titlepage.txt

### GENERATE SCRIPT PAGE
echo "This output was generated by the following code:" > scriptpage.txt
cat ../${0} >> scriptpage.txt


### SPLIT KEY INTO PARTS
# Ref: https://gist.github.com/joostrijneveld/59ab61faa21910c8434c
split -l 12 -a 2 -d --additional-suffix=.txt $KEYNAME


### GENERATE QR CODES FROM KEY PARTS
# qrencode -l H and qrencode -l Q caused problems when reading with zbarimg
for f in x*; do cat $f | head -c -1 | qrencode -o qr-$f.png; done

### CROSS CHECK QR CODES
echo "Cross checking QR codes:"
for f in x*; do
    echo "Reading QR code qr-$f.png:"
    zbarimg --raw qr-$f.png > temp
    echo "Diff-comparing output of qr-$f.png with $f:"
    # Ref: http://stackoverflow.com/a/23497594
    diff temp $f 2>&1
    if [ $? != 0 ]
    then
        echo "Uh oh... difference found in qr-$f.png... exiting.\n"
        exit 1
    fi
done


### CONVERT TEXT KEYS TO PNG FOR PAGE GENERATION
# Ref: http://www.imagemagick.org/script/command-line-options.php#family
echo "Converting textual key parts to png:"
for f in x*.txt; do convert -family 'Courier New' text:$f txt-$f.png; done

### PAGE GENERATION
# Ref: http://www.imagemagick.org/Usage/annotating/#gravity_image
# convert hintergrundtext -gravity vordergrundqr -geometry platz ...

# find files without extension
# Ref: http://unix.stackexchange.com/a/144209
# for f in `find . -type f ! -name "*.*"`; do echo $f; done
# Ref: http://unix.stackexchange.com/a/87665
# find . -maxdepth 1 ! -name "*.*" -o -name ".*[^.]*"
echo "Generate single pages"
i=1
for f in x*; do
    echo "Preparing page $i: $f"
    convert txt-$f.png -gravity north -annotate +10+10 "$f" \
    -gravity South -annotate +10+35 "$f" \
    -gravity South qr-$f.png -geometry +10+40 -compose Bumpmap -composite \
    -annotate +10+10 "Page $i" \
    out$i-$f.png
    i=$(($i + 1))
done


### PDF COMPOSITION
echo "Compose pages to ps"
a2ps -1 -o $KEYNAME.ps titlepage.txt scriptpage.txt `find . -name "out*" | sort`
echo "Converting to pdf"
ps2pdf $KEYNAME.ps

### CROSS CHECK PDF
echo "Cross checking QR codes in pdf with original key"
zbarimg --raw $KEYNAME.pdf > temp
diff temp $KEYNAME 2>&1
if [ $? != 0 ]
then
    echo "Uh oh... difference found in $KEYNAME.pdf... exiting.\n"
    exit 1
fi

echo "Moving $KEYNAME.pdf to script folder"
mv $KEYNAME.pdf ../
cd ..
echo "Removing temporary directory $TEMPDIR"
rm -r $TEMPDIR