Encryption program for a messenger app I am building an encryption program for a messenger app I am developing. 

I was wondering if the code looks clean and succinct, and at the same times is safe and secure:

import random
import os
import time

key = os.urandom(64)

def encrypt(_key, message):
    letter_map_message = []
    ascii_msg_value = ''.join(str(ord(c)) for c in message)
    for c in message:
        ''.join(str(ord(c)))
        letter_map_message.append(ord(c))
    ascii_key_value = ''.join(str(ord(x)) for x in str(_key))
    new_msg_encrypted = int(ascii_msg_value) * int(ascii_key_value)
    returned = (new_msg_encrypted, letter_map_message)
    return returned;

def decrypt(_key, message, letter_map):
    ascii_key_value = ''.join(str(ord(x)) for x in str(_key))
    msg_ascii_divided = int(message)/int(ascii_key_value)
    letters = []
    for c in range(len(letter_map)):
        li = letter_map[c]
        c = int(li)
        letter = chr(c)
        letters.append(letter)
    new_msg_decrypted = ''.join(letters)
    return new_msg_decrypted;

encrypted = encrypt(key, "HEHHEHEHHE")
print(encrypted[0])
decrypted = decrypt(key, encrypted[0], encrypted[1])
print(decrypted)
This is not a secure system.

I haven't actually read your code, but unless you have a team of at least 10 security researchers who have been doing nothing other than testing this encryption scheme, you should not use it in production code. You should be using a crypto library built by someone that knows what they are doing. I would recommend cryptography. Docs are here https://cryptography.io/en/latest/. Good luck