decrypt.py 文件源码

def decrypt_file(key, in_filename, out_filename=None, chunksize=24*1024):

    # Split .crypt extension to restore file format
    if not out_filename:
        out_filename = os.path.splitext(in_filename)[0]

    with open(in_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(out_filename, 'wb') as outfile:
            while True:
                chunk = infile.read(chunksize)
                if len(chunk) == 0:
                    break
                outfile.write(decryptor.decrypt(chunk))

        # Truncate file to original size
            outfile.truncate(origsize)