Scritpts to handle Digital Green Certificates

decode-dgc_hupdf.py

#!/usr/bin/env python3

import binascii
import json
import sys
import zlib
 
import base45
import base64
import cbor2
import PyPDF2

from cose.messages import CoseMessage
from pyzbar import pyzbar
from PIL import Image


with open(sys.argv[1], 'rb') as f:
    pdf = PyPDF2.PdfFileReader(f)
    qrobject = pdf.getPage(0)['/Resources']['/XObject']['/Im5']
    qrimage = Image.frombytes('1', (qrobject['/Width'], qrobject['/Height']), qrobject.getData())
    qrdata = pyzbar.decode(qrimage)
    decoded = base45.b45decode(qrdata[0].data[4:])
    decompressed = zlib.decompress(decoded)
    cose_message = CoseMessage.decode(decompressed)

    sig = cose_message.signature
    r = int(binascii.hexlify(sig[:32]), 16)
    s = int(binascii.hexlify(sig[32:]), 16)
    print(f"signature: {base64.b64encode(sig).decode('utf-8')}\n\tr: {r}\n\ts: {s}")

    payload = cbor2.loads(cose_message.payload)
    print(f"payload: \n{json.dumps(payload, indent=4)}")

decode-dgc_img.py

#!/usr/bin/env python3

import binascii
import json
import sys
import zlib
 
import base45
import base64
import cbor2

from cose.messages import CoseMessage
from pyzbar import pyzbar
from PIL import Image


qrimage = Image.open(sys.argv[1])
qrdata = pyzbar.decode(qrimage)
decoded = base45.b45decode(qrdata[0].data[4:])
decompressed = zlib.decompress(decoded)
cose_message = CoseMessage.decode(decompressed)

sig = cose_message.signature
r = int(binascii.hexlify(sig[:32]), 16)
s = int(binascii.hexlify(sig[32:]), 16)
print(f"signature: {base64.b64encode(sig).decode('utf-8')}\n\tr: {r}\n\ts: {s}")

payload = cbor2.loads(cose_message.payload)
print(f"payload: \n{json.dumps(payload, indent=4)}")

generate-invalid-dgc_hupdf.py

#!/usr/bin/env python3

import json
import sys
import zlib
 
import base45
import cbor2
import PyPDF2
import qrcode

from cose.messages import CoseMessage
from pyzbar import pyzbar
from PIL import Image


with open(sys.argv[1], 'rb') as f:
    pdf = PyPDF2.PdfFileReader(f)
    qrobject = pdf.getPage(0)['/Resources']['/XObject']['/Im5']
    qrimage = Image.frombytes('1', (qrobject['/Width'], qrobject['/Height']), qrobject.getData())
    qrdata = pyzbar.decode(qrimage)
    decoded = base45.b45decode(qrdata[0].data[4:])
    decompressed = zlib.decompress(decoded)

    decompressed = decompressed.replace(b'Budapest', b'xxxxxxxx')
    compressed = zlib.compress(decompressed)
    encoded = base45.b45encode(compressed)
    qr = qrcode.QRCode(
            version=1,
            error_correction=qrcode.constants.ERROR_CORRECT_H,
            box_size=10,border=4)
    qr.add_data(b'HC1:' + encoded)
    qr.make(fit=True)
    img = qr.make_image(fill_color="black", back_color="white")
    img.save("wrong.png")