base64url_decode TypeError: must be str, not bytes

[rvernica]

Example copied from docs:

>>> from jose.utils import base64url_decode
>>> token = "eyJhbGciOiJIUzI1NiIsImtpZCI6IjAxOGMwYWU1LTRkOWItNDcxYi1iZmQ2LWVlZjMxNGJjNzAzNyJ9.SXTigJlzIGEgZGFuZ2Vyb3VzIGJ1c2luZXNzLCBGcm9kbywgZ29pbmcgb3V0IHlvdXIgZG9vci4gWW91IHN0ZXAgb250byB0aGUgcm9hZCwgYW5kIGlmIHlvdSBkb24ndCBrZWVwIHlvdXIgZmVldCwgdGhlcmXigJlzIG5vIGtub3dpbmcgd2hlcmUgeW91IG1pZ2h0IGJlIHN3ZXB0IG9mZiB0by4.s0h6KThzkfBBBkLspW1h84VsJZFTsPPqMDA7g1Md7p0"
>>> message, encoded_sig = token.rsplit('.', 1)
>>> decoded_sig = base64url_decode(encoded_sig)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/vernica/.local/lib/python3.6/site-packages/jose/utils.py", line 88, in base64url_decode
    input += b'=' * (4 - rem)
TypeError: must be str, not bytes

Environment:

• Python 3.6.2
• jose 1.4.0

[f1yingbanana]

In python 3, you have to encode your input to bytes first, because implicit conversion between str and byte is no longer possible. Try:
base64url_decode(encoded_sig.encode('utf-8'))

[karlmutch]

The append operation within the base64 decode functions is appending bytes not strings resulting in byte arrays being sent to the python base64 functions and failing.

using the encode function on the input strings for padding does not help the root issue.

An example can be seen here:

python-jose/jose/utils.py

Line 88 in e31416a

input += b'=' * (4 - rem)

[karlmutch]

In python 3, you have to encode your input to bytes first, because implicit conversion between str and byte is no longer possible. Try:
base64url_decode(encoded_sig.encode('utf-8'))

The internal functions used for padding will void this fix. See comment below.