Implementation of One Time Pad Cipher in Python

one_time_pad.py

import os
import base64

class OneTimePad:
    def encode_cipher(self,_string, key):
        key = base64.b64decode(key)
        retval = []
        for k, v in zip(_string, key):
            retval.append(int(ord(k) ^ v))
        return base64.b64encode(bytes(retval))

    def decode_cipher(self,encoded, key):
        retval = []
        encoded = base64.b64decode(encoded)
        key = base64.b64decode(key)
        for k, v in zip(encoded, key):
            retval.append(int(k ^ v))
        return bytes(retval)

plaintext = "hello how are you"
key = base64.b64encode(os.urandom(len(plaintext)))

cipher = OneTimePad()
ciphertext = cipher.encode_cipher(plaintext,key)
plaintext2 = cipher.decode_cipher(ciphertext,key)
print("Encrypted:",ciphertext)
print("Decrypted:",plaintext2)

This is not a practical cipher but highly secure since the encryption key is random every time and has same length as that of the message