sasuke-duck/wks-key

wks-key's Issues

Ciphertext with incorrect length

I get this error witch certain PSSH. Example:

License URL: https://lic.drmtoday.com/license-proxy-widevine/cenc/

Input MPD URL: https://dash.hoopladigital.com/via_hdnfy207a/Manifest.mpd

Generating PSSH:.....

PSSH: AAAAVHBzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAADQIARIQmrqeB0TpzjSbHIDSSLtrehoIY2FzdGxhYnMiEJq6ngdE6c40mxyA0ki7a3oqAlNE
/home/removed/Downloads/wks-keys_v3/pywidevine/L3/cdm/cdm.py:260: RuntimeWarning: Unexpected end-group tag: Not all data was converted
  license.ParseFromString(base64.b64decode(license_b64))
Traceback (most recent call last):
  File "./keys.py", line 46, in <module>
    correct, keys = WV_Function(pssh, lic_url)
  File "./keys.py", line 42, in WV_Function
    wvdecrypt.update_license(license_b64)
  File "/home/removed/Downloads/wks-keys_v3/pywidevine/L3/decrypt/wvdecryptcustom.py", line 58, in update_license
    self.cdm.provide_license(self.session, license_b64)
  File "/home/removed/Downloads/wks-keys_v3/pywidevine/L3/cdm/cdm.py", line 275, in provide_license
    session.session_key = oaep_cipher.decrypt(license.SessionKey)
  File "/home/removed/.local/lib/python3.8/site-packages/Cryptodome/Cipher/PKCS1_OAEP.py", line 167, in decrypt
    raise ValueError("Ciphertext with incorrect length.")
ValueError: Ciphertext with incorrect length.

Suggestion:-

You've taken a decision to parse the MPD to get PSSH with option for a manual input on failing to find it. All sensible stuff.

Why not go the extra mile if PSSH isn't found,? Find and create the PSSH from the Default Kid instead. There are Kid to pssh decoders around since forever. Hee is one.

import base64

def createpsshfromkid(kid_value):
kid_value = kid_value.replace('-', '')
assert len(kid_value) == 32 and not isinstance(kid_value, bytes), "wrong KID length"
array_of_bytes = bytearray(b'\x00\x00\x002pssh\x00\x00\x00\x00')
array_of_bytes.extend(bytes.fromhex("edef8ba979d64acea3c827dcd51d21ed"))
array_of_bytes.extend(b'\x00\x00\x00\x12\x12\x10')
array_of_bytes.extend(bytes.fromhex(kid_value.replace("-", "")))
return base64.b64encode(bytes.fromhex(array_of_bytes.hex())).decode('utf-8')

kid = input("Enter the KID:")

print(createpsshfromkid(kid))