from Crypto.Cipher import AES
import os, random, struct
def decrypt_file(key, filename, chunk_size=24*1024):
output_filename = os.path.splitext(filename)[0]
with open(filename, 'rb') as infile:
origsize = struct.unpack('<Q', infile.read(struct.calcsize('Q')))[0]
iv = infile.read(16)
decryptor = AES.new(key, AES.MODE_CBC, iv)
with open(output_filename, 'wb') as outfile:
while True:
chunk = infile.read(chunk_size)
if len(chunk) == 0:
break
outfile.write(decryptor.decrypt(chunk))
outfile.truncate(origsize)
decrypt_file('abcdefghji123456', 'sample-file.txt.encrypted');
