Encrypt a Folder

encrypt_folder.py

from hashlib import md5
from Crypto.Cipher import AES
from Crypto import Random
import base64
import os


def derive_key_and_iv(password, salt, key_length, iv_length):
    d = d_i = ''
    while len(d) < key_length + iv_length:
        d_i = md5(d_i + password + salt).digest()
        d += d_i
    return d[:key_length], d[key_length:key_length+iv_length]

def encrypt(in_file, out_file, password, key_length=32):
    bs = AES.block_size
    salt = Random.new().read(bs - len('Salted__'))
    key, iv = derive_key_and_iv(password, salt, key_length, bs)
    cipher = AES.new(key, AES.MODE_CBC, iv)
    #print in_file
    in_file = file(in_file, 'rb')
    out_file = file(out_file, 'wb')
    out_file.write('Salted__' + salt)
    finished = False
    while not finished:
        chunk = in_file.read(1024 * bs)
        if len(chunk) == 0 or len(chunk) % bs != 0:
            padding_length = bs - (len(chunk) % bs)
            chunk += padding_length * chr(padding_length)
            finished = True
        out_file.write(cipher.encrypt(chunk))
    in_file.close()
    out_file.close()

def decrypt(in_file, out_file, password, key_length=32):
    bs = AES.block_size

    in_file = file(in_file, 'rb')
    out_file = file(out_file, 'wb')
    salt = in_file.read(bs)[len('Salted__'):]
    key, iv = derive_key_and_iv(password, salt, key_length, bs)
    cipher = AES.new(key, AES.MODE_CBC, iv)
    next_chunk = ''
    finished = False
    while not finished:
        chunk, next_chunk = next_chunk, cipher.decrypt(in_file.read(1024 * bs))
        if len(next_chunk) == 0:
            padding_length = ord(chunk[-1])
            if padding_length < 1 or padding_length > bs:
                raise ValueError("bad decrypt pad (%d)" % padding_length)
            # all the pad-bytes must be the same
            if chunk[-padding_length:] != (padding_length * chr(padding_length)):
                # this is similar to the bad decrypt:evp_enc.c from openssl program
                raise ValueError("bad decrypt")
            chunk = chunk[:-padding_length]
            finished = True
        out_file.write(chunk)    
    in_file.close()
    out_file.close()

def encode(in_file, out_file):
    in_file = file(in_file, 'rb')
    out_file = file(out_file, 'wb')
    data = in_file.read()
    out_file.write(base64.b64encode(data))    
    in_file.close()
    out_file.close()

def decode(in_file, out_file):
    in_file = file(in_file, 'rb')
    out_file = file(out_file, 'wb')
    data = in_file.read()
    out_file.write(base64.b64decode(data))    
    in_file.close()
    out_file.close()

def create_new_file( _file):
    return _file.replace('.','__e.')

def restore_file( _file):
    return _file.replace('__e.','.')

def encrypt_folder( path, password):
    for i in os.walk(path):
        for _file in i[2]:
            try:
                print "File Encrypting is ",path+_file 
                new_file = path+create_new_file(_file)
                old_file = path+_file
                encrypt(old_file,new_file,password) 
                print "Deleting old file"
                os.remove(old_file)
            except:
                print "Please check your input files"
                pass
def decrypt_folder(path, password):
    for _files in os.walk(path):
        for _file in _files[2]:
            try:
                print "Decrypting the file", path+_file
                new_file = path+restore_file(_file)
                old_file = path+_file
                decrypt(old_file,new_file,password)
                print "Deleting the encrypted file"
                os.remove(old_file)
            except:
                print "Please check your input files"
                pass

__password = raw_input("Please provide a password:\n")
__path = raw_input("Please provide a path to the folder to Encrypt/Decrypt")
print "1. Encrypt"
print "2. Decrypt"
print "Please note that do not encrypt the encrypted files"
print "The path you provided is:\n", __path
option = input("Please provide an option only in Integers ")
if option == 1:
    encrypt_folder(__path, __password)
if option == 2:
    decrypt_folder(__path, __password)