GPG to Printable Datamatrix

gpg-key-to-datamatrix.sh

#!/bin/bash

add_caption() {
 convert "${1}" \
   -quality 100 \
   -units PixelsPerInch \
   -resize 200% \
    \( -background white -fill black -size x48 \
       label:"${2}" -trim +repage \
       -bordercolor white -border 10 \
    \) -gravity South -append \
    -density 300 \
    "caption_${1}" \
    && mv "caption_${1}" "${1}"
}

generate_image() {
  dmtxwrite --margin=80 --resolution=300 --output="${1}.jpg" -e8 "${1}"
  add_caption "${1}.jpg" "${1}"
}

secret_key_to_image() {
  local key="${1}"
  gpg --export-secret-keys "${key}" | split -a1 -b1556 -d - secret.gpg.
  for i in secret.gpg.[0-9]; do
    generate_image "${i}" && rm "${i}"
  done
}

public_key_to_image() {
  local key="${1}"
  gpg --export "${key}"             | split -a1 -b1556 -d - public.gpg.
  for i in public.gpg.[0-9]; do
    generate_image "${i}" && rm "${i}"
  done
}

image_to_key() {
  local name="${1}"
  shift
  ( for i in $@; do dmtxread "${i}"; done ) > "${name}.gpg"
}

generate_pdf() {
  local output="${1}"
  shift
  local resolution="2480x3508";
  convert -resize "${resolution}" -extent "${resolution}" \
    -background white -gravity Center -border 30 -bordercolor white \
    $@ \
    "${output}"
}

import() {
  gpg --import < "${1}"
}

import_from_pdf() {
  local pdf="${1}"
  convert "${pdf}" "all.png"
  image_to_key public all-0.png all-1.png
  image_to_key revocation-certificate all-2.png
  image_to_key secret all-3.png all-4.png all-5.png
  import public.gpg
  import secret.gpg
  # revocation certificate is not imported, because it revokes the key when
  # imported
}

export_to_pdf() {
  local key="${1}"
  secret_key_to_image "${key}"
  public_key_to_image "${key}"
  # FIXME generate revocation-certificate
  generate_pdf all.pdf \
    public.gpg.[0-9].jpg \
    secret.gpg.[0-9].jpg
}

action="${1}"
shift

case ${action} in
  save) key_to_image $@;;
  load) image_to_key $@;;
  add_caption) add_caption $@;;
  generate_image) generate_image $@;;
  generate_pdf) generate_pdf $@;;
  import) import $@;;
  import_from_pdf) import_from_pdf $@;;
  export_to_pdf) export_to_pdf $@;;
esac