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Python script to decode SHC-encoded JWTs generated by SmartHealth Cards.
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| #!/usr/bin/env python3 | |
| from sys import stdin, stdout, stderr | |
| import base64 | |
| import re | |
| import zlib | |
| import argparse | |
| ap = argparse.ArgumentParser() | |
| ap.add_argument('--header', action='store_true', help='Output the JWT header instead of the payload') | |
| args = ap.parse_args() | |
| def b64dec(data): | |
| nipad = len(data) % 4 | |
| if nipad > 0: | |
| data += "=" * (4 - nipad) | |
| return base64.urlsafe_b64decode(data) | |
| def readSHC(): | |
| result = "" | |
| while True: | |
| n = stdin.read(2) | |
| if not n: | |
| break | |
| try: | |
| n = int(n) + 45 | |
| result += chr(n) | |
| except ValueError: | |
| pass | |
| return result | |
| scheme = stdin.read(5) | |
| if scheme != "shc:/": | |
| print("Input is not in SHC scheme format", file = stderr) | |
| sys.exit(1) | |
| result = readSHC() | |
| m = re.match("^([\w\d\.\-_]+)\.([\w\d\.\-_]+)\.([\w\d\.\-_]+)$", result) | |
| if m: | |
| parts = m.groups() | |
| else: | |
| print("Encoded SHC is not a valid JWT", file = stderr) | |
| sys.exit(2) | |
| if args.header: | |
| header = b64dec(parts[0]).decode('utf-8') | |
| print (header) | |
| else: | |
| payload = b64dec(parts[1]) | |
| payload = zlib.decompress(payload, wbits = -15) | |
| payload = payload.decode("utf-8") | |
| print (payload) |
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Basic Usage Instructions
zbarimgto decode the QR codeQR-Code...)shc-jwt.pyyqExample:
zbarimg path-to-qrcode.jpg | sed 's/^QR-Code://' | shc-jwt.py | yq -y .