from numbthy import *
import random

size = 8
pad = 32

def Encode(p, q, plain):
    cipher = ""
    N = p * q
    phi = (p-1)*(q-1)
    # for e in reversed(xrange(2, phi)):
    #   if gcd(e, phi) == 1:
    #       break
    while True:
        e = random.randint(2, phi)
        if gcd(e, phi) == 1:
            break
        pass
    print "e : " + str(e)
    for i in range(0, len(plain), size):
        M = int(plain[i:i+size], 2)
        cipher += bin(pow(M, e, N))[2:].rjust(pad , "0")
    return cipher, e

def Decode(cipher, p , q, e):
    N = p * q
    phi = (p - 1) * (q - 1)
    d = invmod(e, phi)
    plain = ""
    for i in range(0, len(cipher), pad):
        C = int(cipher[i:i+pad], 2)
        plain += hex(pow(C, d, N))[2:].decode("hex")
    return plain


file = "plain.txt"
f = open(file, 'rb').read()
plain = ''.join(format(ord(x), 'b').rjust(8, "0") for x in f)

p = 859
q = 997

cipher, e  = Encode(p, q, plain)
print "cipher : " + cipher

plaintext = Decode(cipher, p, q, e)
print "plaintext : " + plaintext