Custom base64 encoder/decoder

custom_base64.py

#!/usr/bin/env python3

import base64

custom_b64 = "CDEFGHIJKLMNOPQRSTUVWXYZABcdefghijklmnopqrstuvwxyzab0123456789+/"
original_b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"


def encode(clear_text):
    b64 = base64.b64encode(clear_text)
    encoded_text = ""
    for ch in b64:
        ch = chr(ch)
        if ch in custom_b64:
            encoded_text += custom_b64[original_b64.find(ch)]
        elif ch == '=':
            encoded_text += "="
    return encoded_text


def decode(encoded_text):
    base64_eq = ""
    for ch in encoded_text:
        if ch in custom_b64:
            base64_eq += original_b64[custom_b64.find(ch)]
        elif ch == "=":
            base64_eq += "="
    return base64.b64decode(base64_eq.encode("ascii"))


if __name__ == "__main__":
    text = b"dir\n"
    encoded = encode(text)
    decoded = decode(encoded)
    print("Encoded : {}, Decoded : {}".format(encoded, decoded))