encrypt.py

#!/usr/bin/python

from getpass import getpass
import os, random
from Crypto.Cipher import AES
from Crypto.Hash import SHA256
def encrypt(key, filename):
	chunksize = 64*1024
	outputFile = '(encrypted)'+filename
	filesize = str(os.path.getsize(filename)).zfill(16)
	IV = ""
	for i in range(16):
		IV += chr(random.randint(0,0xFF))
	encryptor = AES.new(key, AES.MODE_CBC, IV)
	with open(filename, 'rb') as infile:
		with open (outputFile, 'wb') as outfile:
			outfile.write(filesize)
			outfile.write(IV)
			while True:
				chunk = infile.read(chunksize)
				if len (chunk) == 0:
					break
				elif len(chunk) % 16 != 0 :
					chunk += ' ' * (16 - (len(chunk) % 16))

				outfile.write(encryptor.encrypt(chunk))
def decrypt(key, filename):
	chunksize = 64*1024
	outputFile = filename[11:]
	with open(filename, 'rb') as infile:
		filesize = long(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)
	return hasher.digest()
def main():
	print '#'*30
	print '\tencrypt files'
	print '#'*30+'\n'
	choice = raw_input('world you like to (E)ncrypt or (D)ecrypt ? ')
	if choice == 'E':
		filename = raw_input('File to encrypt : ')
		passw = getpass('Password : ')
		password = passw
		encrypt(getKey(password), filename)
		print "Done."
	elif choice == 'D':
		filename = raw_input('File to decrypt : ')
		passw = getpass('Password : ')
		password = passw
		decrypt(getKey(password), filename)
		print "Done."
	else:
		print "No option selected, closing..."

if __name__=='__main__':
	main()