Decrypt Hulu SAMI (.smi) subtitles

decrypt.py

# Don't use this, just grab WebVTT subtitles instead loool
# This was just how I spent a lazy Sunday evening

from Crypto.Cipher import AES
from Crypto.Util import Padding
import binascii

import glob
import os
from xml.etree import ElementTree

KEY = binascii.unhexlify("4878B22E76379B55C962B18DDBC188D82299F8F52E3E698D0FAF29A40ED64B21")
IV = b"WA7hap7AGUkevuth"
DIRECTORY = "decrypted"

if not os.path.exists(DIRECTORY):
    os.makedirs(DIRECTORY)

for file in glob.glob("*.smi"):
    tree = ElementTree.parse(file)
    encrypted_syncs = tree.findall(".//*[@Encrypted='true']")
    if len(encrypted_syncs) == 0:
        continue
    for sync in encrypted_syncs:
        cipher = AES.new(KEY, AES.MODE_CBC, IV)
        ciphertext = binascii.unhexlify(sync.text.strip())
        plaintext = Padding.unpad(cipher.decrypt(ciphertext), AES.block_size).decode()
        subtree = ElementTree.fromstring(plaintext)
        sync.text = None
        sync.append(subtree)
        sync.attrib.pop("Encrypted", None)

    tree.write(os.path.join(DIRECTORY, file), encoding="unicode", short_empty_elements=False)