base64 that actually encodes URL safe (no '=' nonsense)

encode.py

"""
base64's `urlsafe_b64encode` uses '=' as padding.
These are not URL safe when used in URL paramaters.
Functions below work around this to strip/add back in padding.

See:
https://docs.python.org/2/library/base64.html
https://mail.python.org/pipermail/python-bugs-list/2007-February/037195.html
"""

import base64


def base64_encode(string):
    """
    Removes any `=` used as padding from the encoded string.
    """
    encoded = base64.urlsafe_b64encode(string)
    return encoded.rstrip("=")


def base64_decode(string):
    """
    Adds back in the required padding before decoding.
    """
    padding = 4 - (len(string) % 4)
    string = string + ("=" * padding)
    return base64.urlsafe_b64decode(string)

example

>>> test = "helloworld"
>>> encode_base64(test)
'aGVsbG93b3JsZA'
>>> e = encode_base64(test)
>>> decode_base64(e)
'helloworld'
>>> test = "Hello World"
>>> encoded = encode_base64(test)
>>> print encoded
SGVsbG8gV29ybGQ
>>> decoded = decode_base64(encoded)
>>> decoded
'Hello World'
>>> decoded == test
True