over_simplified_async_encryption.py

from binascii import a2b_base64 as b64decode, b2a_base64 as b64encode

a, b = 13, 7
PUB = 5
PRIV = 29
MAX = a * b

def cycleBit(v, c, m):
    v2 = v
    for i in range(c - 1):
        v2 = (v2 * v) % m
    return v2

def crypt(s, k, m):
    ret = []
    for v in map(ord, s):
        ret.append(cycleBit(v, k, m))

    return "".join(map(chr, ret))

def encrypt(message, key, m):
    b = crypt(message, key, m)
    return b64encode(b)

def decrypt(message, key, m):
    s = b64decode(message)
    return crypt(s, key, m)

MySecret = "HELLO, WORLD"

print "Encrypting message: " + MySecret

c = encrypt(MySecret, PUB, MAX)
print "Encrypted message is: " + c

m = decrypt(c, PRIV, MAX)
print "Decrypted message is: " + m