helpers.py

import base64
import json

def get_payload_from_token(token) -> dict:
    if not token:
        return {}
    payload = token.split('.')[1]
    payload += "=" * ((4 - len(payload) % 4) % 4) # solve the padding issue of the base64 python lib
    return json.loads(base64.urlsafe_b64decode(payload).decode())


def get_header_from_token(token) -> dict:
    if not token:
        return {}
    header = token.split('.')[0]
    header += "=" * ((4 - len(header) % 4) % 4) # solve the padding issue of the base64 python lib
    return json.loads(base64.urlsafe_b64decode(header).decode())


def alg(key):
    key = json.loads(key) if isinstance(key, str) else key
    if key['kty'] == 'EC':
        if key['crv'] in ['secp256k1', 'P-256K']:
            key['crv'] = 'secp256k1'
            return 'ES256K'
        elif key['crv'] == 'P-256':
            return 'ES256'
        elif key['crv'] == 'P-384':
            return 'ES384'
        elif key['crv'] == 'P-521':
            return 'ES512'
        else:
            raise Exception("Curve not supported")
    elif key['kty'] == 'RSA':
        return 'RS256'
    elif key['kty'] == 'OKP':
        return 'EdDSA'
    else:
        raise Exception("Key type not supported")