Developer: One time pad

Well this week I have to make a program using the one time pad method.

What I have to do?

First, I have to create x number of keys, this keys have to be binary numbers
Second, the program asks the user for a message to encrypt. This program writes the key that use and the cypher text in a file
Third, the program using another function opens the file with the cypher text and the key and decrypt the cypher text.

For this program I use the xor function to encrypt the message, so the program takes each value of the binary text and each value of the key and applies them the xor function

An example could be if the binary message is 0100101 and the key 0001101, the cypher text would be:

message: 0100101

key: 0001101

cypher: 0101000

Here is my program:

(Note: due to time I couldn't make the function to decrypt the message, I just only implement the function to encrypt the message)

	#!/usr/bin/python

	import random
	from numpy import *

	def gen_keys():
	i = 0
	j = 0
	keys = open("notebook.txt","w")#file for the keys

	while i < 10:
	while j < 7:
	rand = random.randint(0,2)#random integer beetween 0 and 2
	keys.write(str(rand))#write the random integer in the file
	j = j+1
	keys.write("\n")#newline
	j=0
	i = i+1
	keys.close()

	def cipher():
	key = open("notebook.txt","r")#open file just for reading it
	msg = raw_input("Mensaje: ")#reads a message from the user
	size = len(msg)#size of the message
	y = 0
	cipher_text = []
	x = 0
	while x < 1:
	dato = key.readline()#read just the first line, that is the key tha we are going to use
	x = x+1
	cipher_key = str(dato[:7])

	while y < size:
	letter = ord(msg[y])#convert into a integer number each character of the message
	binary = bin(letter)#convert into binary value each integer number
	aux = binary[2:]#bin() function adds two values that we dont need at the beginning
	str(aux)#convert into string the binary value
	print "binary: ", aux
	print "key: ", cipher_key
	i=0
	while i < len(aux):
	bit = int(aux[i]) ^ int(cipher_key[i])#xor function between the key and the binary message
	cipher_text = cipher_text + [str(bit)]#concatenate all the values
	i = i+1
	y = y + 1
	cipher_text=display_bits(cipher_text)#display as string
	#int(cipher_text)
	print len(cipher_text)
	key.close()#close the file
	bob = open("cipher.txt","w")#file for the key and cipher text
	bob.write(cipher_key)#writes the key into the file
	bob.write("\n")
	bob.write(cipher_text)#writes the cypher text into de file
	bob.close()

	#function to display the bits as string
	def display_bits(b):
	return ''.join(str(i) for i in b)

	#not working. This is going to be to display the each character of the cypher text as text not as binary
	def algorithm(bit):
	assert len(bit) == 7
	ascii = 0
	for e in bit:
	ascii = (ascii * 2) + int(e)
	print unichr(ascii)
	f = open("cypher.txt", "a")
	f.write(unichr(ascii))
	f.write(" ")
	f.close
	return str(ascii)

	#function to display the cipher text into normal text
	def bits_to_string(bits):
	return ' '.join([algorithm(bits[i:i + 7])
	for i in range(0, len(bits), 7)])

	gen_keys()
	cipher()