decrypt.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#

import os, time
from Crypto.Cipher import AES
from Crypto.Hash import SHA256
from Crypto import Random


def decrypt(key, filename):
	chunksize = 64 * 1024
	outputFile = filename.split('en')[1]

	with open(filename, 'rb') as infile:
		filesize = int(infile.read(16))
		IV = infile.read(16)
		decryptor = AES.new(key, AES.MODE_CBC, IV)

		with open(outputFile, 'wb') as outfile:
			while True:
				chunk = infile.read(chunksize)

				if len(chunk) == 0:
					break

				outfile.write(decryptor.decrypt(chunk))
			outfile.truncate(filesize)


def getkey(password):
	hasher = SHA256.new(password.encode('utf-8'))
	return hasher.digest()
	

key = "sahay"

filename = "enim_msg.txt" #the output file would be "im_msg.txt"

decrypt(getkey(key), filename)