mirror of
https://github.com/devine-dl/pywidevine.git
synced 2024-10-30 05:29:21 +00:00
69 lines
3.7 KiB
Markdown
69 lines
3.7 KiB
Markdown
# pywidevine
|
|
|
|
Widevine CDM (Content Decryption Module) implementation in Python.
|
|
|
|
## Disclaimer
|
|
|
|
1. This project requires the use of a Google provisioned private key and Client Identification blob.
|
|
2. Neither of them are provided by this project.
|
|
3. Public test provisions are available to use for testing this project.
|
|
4. License Servers have the ability to block requests from test provisions.
|
|
5. This project does not condone piracy or any action against the terms of the DRM systems.
|
|
6. All efforts in this project have been the result of Reverse Engineering and Trial & Error.
|
|
|
|
## Protocol
|
|
|
|
|
|
|
|
*Credit*: w3.org
|
|
|
|
Almost the entire Widevine Protocol seen above is implemented except for Sessions which I will be implementing soon.
|
|
Currently, only one session can be made and used at a time or problems will happen.
|
|
|
|
### Web Server
|
|
|
|
This may be an API/Server in front of a License Server. For example, Netflix's Custom MSL-based API front.
|
|
This is evident by their custom Service Certificate which would only be needed if they had to read the License.
|
|
|
|
### Net, Media Stack and MediaKeySession
|
|
|
|
These generally refer to the Encrypted Media Extensions API on Browsers.
|
|
|
|
Under the assumption of the Android Widevine ecosystem, you can think of `Net` as the Application Code, `Media Stack`
|
|
as the OEM Crypto Library, and `MediaKeySession` as a Session. The orange wrapper titled `Browser` is effectively the
|
|
Application as a whole, while `Platform` (in Green at the bottom) would be the OS or Other libraries.
|
|
|
|
## Key and Output Security
|
|
|
|
*Licenses, Content Keys, and Decrypted Data is not secure in this CDM implementation.*
|
|
|
|
The Content Decryption Module is meant to do all downloading, decrypting, and decoding of content, not just license
|
|
acquisition. This Python implementation only does License Acquisition within the CDM.
|
|
|
|
The section of which a 'Decrypt Frame' call is made would be more of a 'Decrypt File' in this implementation. Just
|
|
returning the original file in plain text defeats the point of the DRM. Even if 'Decrypt File' was somehow secure, the
|
|
Content Keys used to decrypt the files are already exposed to the caller anyway, allowing them to manually decrypt.
|
|
|
|
An attack on a 'Decrypt Frame' system would be analogous to doing an HDMI capture or similar attack. This is because it
|
|
would require re-encoding the video by splicing each individual frame with the right frame-rate, syncing to audio, and
|
|
more.
|
|
|
|
While a 'Decrypt Video' system would be analogous to downloading a Video and passing it through a script. Not much of
|
|
an attack if at all. The only protection against a system like this would be monitoring the provision and acquisitions
|
|
of licenses and prevent them. This can be done by revoking the device provision, or the user or their authorization to
|
|
the service.
|
|
|
|
There isn't any immediate way to secure either Key or Decrypted information within a Python environment that is not
|
|
Hardware backed. Even if obfuscation or some other form of Security by Obscurity was used, this is a Software-based
|
|
Content Protection Module (in Python no less) with no hardware backed security. It would be incredibly trivial to break
|
|
any sort of protection against retrieving the original video data.
|
|
|
|
Though, it's not impossible. Google's Chrome Browser CDM is a simple library extension file programmed in C++ that has
|
|
been improving its security using math and obscurity for years. It's getting harder and harder to break with its latest
|
|
versions only being beaten by Brute-force style methods. However, they have a huge team of very skilled workers, and
|
|
making a CDM in C++ has immediate security benefits and a lot of methods to obscure and obfuscate the code.
|
|
|
|
## License
|
|
|
|
[GNU General Public License, Version 3.0](LICENSE)
|