from Crypto.Cipher import AES
import os
def encrypt_file(key, filename):
chunksize = 64 * 1024
outputFile = "(encrypted)"+filename
filesize = str(os.path.getsize(filename)).zfill(16)
IV = os.urandom(16)
encryptor = AES.new(key, AES.MODE_CBC, IV)
with open(filename, 'rb') as infile:
with open(outputFile, 'wb') as outfile:
outfile.write(filesize.encode('utf-8'))
outfile.write(IV)
while True:
chunk = infile.read(chunksize)
if len(chunk) == 0:
break
elif len(chunk) % 16 != 0:
chunk += b' ' * (16 - (len(chunk) % 16))
outfile.write(encryptor.encrypt(chunk))
def decrypt_file(key, filename):
chunksize = 64 * 1024
outputFile = filename[11:]
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)
key = b'Sixteen byte key'
filename = 'example.txt'
encrypt_file(key, filename)
encrypted_filename = "(encrypted)example.txt"
decrypt_file(key, encrypted_filename)