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Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

1.8.0 - 2023-12-22

Added

  • Added py.typed file to support PEP561 and silence Mypy.

Changed

  • Dropped support for Python 3.7.
  • Recompiled protobuffers for version 4.25.

Fixed

  • Missing yaml dependency as it was only installed alongside the serve extras group.
  • Duplicate Concatenated SignedMessages no longer throw a verification failure in Cdm.set_service_certificate(). To ensure security of the messages, verification will still fail if any of the SignedMessages do not match each other.

New Contributors

1.7.0 - 2023-11-21

  • Supported Serve API: v1.4.3 or newer

Added

  • Ability to specify output filename by specifying a full path or a relative file name in CLI command create-device.
  • Add the staging privacy certificate (staging.google.com) to Cdm.staging_privacy_cert.
    • Similar to common_privacy_cert which would be used on Google's production license server,
    • Though this one is used on Google's staging license server (a production-ready testing server).

Changed

  • Raise an error if a file already exists at the output path in CLI command create-device.
  • Use std-lib xml instead of lxml to reduce dependencies and support ARM (#35).
  • Lessen restriction on Python version to any Python version >=3.7, but <4.0.
    • I was hoping to do ^3.7, but some dependencies also require <4.0 therefore I cannot, for now.
  • Move Key ID parsing to static PSSH.parse_key_ids() method.
  • The shaka-packager subprocess call's return code is now returned from Cdm.decrypt().
  • The flags variable of a Device now defaults to a dict, even if not set.
  • Heavily improve initializing of protobuf objects, improving readability, typing, and linting quite a bit.
  • Renamed Device's _Types enum class to DeviceTypes.

Removed

  • Removed Device.Types class variable alias to _Types enum class as a static linter cannot recognize a class variable as a type. Instead, the actual _Types (now named DeviceTypes) enum should be imported and used instead.

Fixed

  • Ensure output directory exists before creating new .wvd files in CLI command create-device.
  • Ignore empty Key ID values in v4.0.0.0 PlayReadyHeaders.
  • Remove Cdm.system_id class variable as it conflicted with the cdm.system_id class instance variable of the same name. It's also generally not needed. The same data can be gotten via Cdm.uuid.bytes.
  • Casting of type_ when passed a non-int value in Cdm.get_license_challenge().
  • Pass a PSSH object in test CLI command instead of a string.
  • Lower-case and setup __all__ correctly, add missing __all__ in some of the modules.
    • For the longest time I thought it was __ALL__ and an iterable of objects/variables.
    • However, its actually __all__ and explicitly a list of Strings...

New Contributors

1.6.0 - 2023-02-03

  • Supported Serve API: v1.4.3 or newer

Added

  • Support Python 3.11.
  • New CLI command export-device to export WVD files back as files. I.e., a private key and client ID blob file.

1.5.3 - 2022-12-27

  • Supported Serve API: v1.4.3 or newer

Added

  • New utility load_xml() to parse XML data with lxml ignoring Namespaces.
  • PSSH class now have __str__ and __repr__ methods to print the object in more Human-friendly ways.
    • str(pssh) is now identical to pssh.dumps().
    • repr(pssh) or just pssh in some cases will result in a nice overview of the PSSHs contents.
  • New to_playready() method to convert Widevine PSSH Data to PlayReady PSSH Data. Please note that the Checksums for AES-CTR and COCKTAIL KIDs cannot be calculated as the Content Encryption Key would be needed.

Changed

  • The System ID must now be explicitly specified when creating a new PSSH box in PSSH.new().
    • This allows you to now create PlayReady PSSH boxes.
  • The playready_to_widevine() method has been renamed to just to_widevine().

Fixed

  • Correct capitalization of the key_IDs field when making the new box in PSSH.new().
  • Correct the value type of key_IDs value when creating a new box in PSSH.new().
  • Ensure Key IDs are list of UUIDs instead of bytes in PSSH.new().
  • Create v0 PSSH boxes by only setting the key_IDs field when the version is set to 1 in PSSH.new().
  • Fix loading of PlayReadyHeaders (and PlayReadyObjects) as PSSH boxes. It would previously load it under the Widevine SystemID breaking all PlayReady-specific code after construction.
  • Parse Key IDs within PlayReadyHeaders by using the new load_xml() utility to ignore namespaces so that xpath can correctly locate any and all KID tags.
  • Support parsing PlayReadyObjects with more than one PlayReadyHeader (more than one record).

1.5.2 - 2022-10-11

  • Supported Serve API: v1.4.3 or newer

Fixed

  • Fixed license signature calculation for newer Widevine Server licenses on OEM Crypto v16.0.0 or newer. The oemcrypto_core_message data needed to be part of the HMAC ingest if available.

1.5.1 - 2022-10-23

  • Supported Serve API: v1.4.3 or newer

Added

  • Support for big-int Key IDs in PSSH. All integer values are converted to a UUID and are loaded big-endian.
  • Import path shortcuts in the __init__.py package constructor to all the user classes.
    • Now you can do e.g., from pywidevine import PSSH instead of from pywidevine.pssh import PSSH.
    • You can still do it the full direct way if you want.
  • Parsing check to the raw DrmCertificate in Cdm.set_service_certificate().

Changed

  • Service Certificates are now stored in the session as a SignedDrmCertificate.
    • This is to keep the signature with the Certificate, without wrapping it in a SignedMessage unnecessarily.
  • Reduced the maximum concurrent Cdm sessions from 50 to 16 as it seems to be a more common limit on more up-to-date devices and versions of OEMCrypto. This also helps encourage people to close their sessions when they are no longer required.

Fixed

  • Acquisition of the Certificate's provider_id in Cdm.set_service_certificate() in some edge cases, but also when you try to remove the certificate by setting it to None.
  • When exporting a PSSH object it will now do so in the same version it was initially loaded or created in. Previously it would always dump as a v1 PSSH box due to a cascading check in pymp4. It now also honors the currently set version in the case it gets overridden.
  • Improved reliability of computing License Signatures by verifying the signature against the original raw License message instead of the re-serialized version of the message.
    • Some license messages when parsed would be slightly different when re-serialized against my protobuf, therefore the computed signature would have always mismatched.

1.5.0 - 2022-09-24

  • Supported Serve API: v1.4.3 or newer

Changed

  • Updated protobuf dependency to v4.x branch with recompiled proto-buffers, specifically v4.21.6.

1.4.4 - 2022-09-24

  • Supported Serve API: v1.4.3 or newer

Security

1.4.3 - 2022-09-10

  • Supported Serve API: v1.4.3 or newer

Added

  • Serve's /get_license_challenge endpoint can now disable privacy mode per-request, even if a service certificate is set, as long as privacy mode is not enforced in the Serve API config.
  • New Cdm method get_service_certificate() to get the currently set service certificate of a Session.

Changed

  • All f-string formatting in log statements have been replaced with logging formatting to save performance when that log wouldn't have been printed.
  • The Serve APIs /open endpoint's function has been renamed from open() to open_() to prevent shadowing the built-in open.

Security

Removed

  • The Protocol image has been removed from the README as it is too broad to Browser scenarios and some stuff on it is too broad. If the viewer is really interested they can Google it to get a much better view into the Protocol.

1.4.2 - 2022-09-05

  • Supported Serve API: v1.4.0 to v1.4.2

Changed

  • Sessions in Cdm.open() are now initialized with a unique session number.
  • Android Cdm Devices now use a Request ID formula similar to OEMCrypto library when generating a Challenge. This formula has yet to be fully confirmed and ironed out, but it is closer than the Chrome Cdm formula.
  • Device no longer throws ValueError exceptions on DecodeErrors if it fails to parse the provided Client ID, or it's VMP data if any. It will now re-raise DecodeError.

Fixed

  • Parsed Proto Messages now go through an elaborate yet efficient verification, it must parse and serialize back to it's received form, byte-for-byte, or it will be rejected.
    • This prevents protobuf from parsing a message that could be a different message depending on the starting bytes.
    • It was possible to bypass some minor checks by providing specially crafted messages that parsed as other messages. However, I haven't noticed any way where this would lead to a vulnerability or anything bad. It mostly just lead to Serve API crashes or just rejected messages down the chain as they wouldn't have the right data within them.

1.4.1 - 2022-08-17

  • Supported Serve API: v1.4.0 to v1.4.2

Changed

  • Rework PSSH.overwrite_key_ids() as an instance method now named PSSH.set_key_ids().
  • Rework PSSH.get_key_ids() as a property method named PSSH.key_ids. This allows swift access to all the Key IDs of the current PSSH object data.
  • Rework PSSH.from_playready_pssh() as an instance method now named PSSH.playready_to_widevine() that now converts the current instances values directly. This allows you to more easily instance as any PSSH, then convert after wards and only if wanted and when needed.

1.4.0 - 2022-08-06

  • Supported Serve API: v1.4.0 to v1.4.2

Added

  • New PSSH boxes can now be manually crafted with PSSH.new().
    • The box can be crafted from arbitrary init_data and/or key_ids.
    • If only key_ids is supplied a new Widevine CENC Header will be created and the key IDs will be put into it.
    • This allows you to make compliant v0 or v1 boxes with as little data as just a Key ID.
  • PSSH boxes can now be exported as MP4 Box objects using pymp4 with PSSH.dump().
  • PSSH boxes can now also be exported as Base64 strings with PSSH.dumps().
  • License Keys can now be obtained from a Cdm session with a parsed license using Cdm.get_keys().
    • This is the alternative to manually accessing the keys from the Cdm._sessions object.
    • It is also available on the Serve API through the new /get_keys endpoint.

Changed

  • PSSH.get_as_box() has been merged into the PSSH constructor, simplifying usage of the PSSH class.
  • PSSH.from_playready_pssh() is now a class method and returns as a PSSH object.
  • Only PSSH objects are now accepted by Cdm.get_license_challenge().
    • You can no longer provide it anything else, that includes base64 or bytes form.
    • You should first parse or make a new PSSH with the PSSH class, and then pass that object.
    • This is to simplify typing and repetition across the codebase.
  • Serve's /challenge endpoint has been changed to /get_license_challenge, and /keys to /parse_license.
    • This is to be consistent with the method names of the underlying Cdm class.
  • Serve now passes the license type value as-is (as a string) instead of parsing it to an integer.
  • Serve now passes the key type value as-is (as a string) instead of parsing it to an integer.
  • Serve no longer returns license keys in the response of the /parse_license endpoint.
    • Once parsed, the /get_keys endpoint should be used to retrieve keys.
  • Privatized the Cdm._sessions class instance variable even more to Cdm.__sessions.
    • If you still need something from it, while not advised, you can call it via cdm._Cdm__sessions.

Removed

  • PSSH.from_key_ids() has been removed entirely, you should now use PSSH.new(key_ids=...) instead.
  • Unnecessary parsing of the license message received by RemoteCdm is now skipped. Parsing should be done by the Serve API as it will be able to actually decrypt and verify the message.
  • All uses of a local Session object has been removed from RemoteCdm. The session is now fully controlled by the remote API and de-synchronization by external alteration or unexpected exceptions is no longer a possibility.

Fixed

  • Correct the WidevinePsshData proto field name from key_id to key_ids in the PSSH class.
  • Handle DecodeError and SignatureMismatch exceptions in the Serve /set_service_certificate endpoint.
  • Handle InvalidInitData and InvalidLicenseType exceptions in the Serve /get_license_challenge endpoint.
  • Handle various exceptions in the Serve /parse_license endpoint.
  • Handle various client-side runtime errors in RemoteCdm with improved error handling.

1.3.1 - 2022-08-04

  • Supported Serve API: v1.3.0 to v1.3.1

Added

  • String value support to the device_type parameter in Cdms constructor.

Changed

  • Serve no longer requires force_privacy_mode to be defined in the config file. It now assumes a default of false.
  • Serve now uses pywidevine serve ... instead of the full project url in the Server header.
  • RemoteCdms Server version check is now case-insensitive.

Fixed

  • RemoteCdms Server version check now ignores other Server/Proxy names prepended or appended to the Server header.
    • For example, if reverse-proxied through Caddy it may have prepended "Caddy" to the Server header.

1.3.0 - 2022-08-04

  • Supported Serve API: v1.3.0 to v1.3.1

Added

  • New Client for using the Serve API; RemoteCdm class. It has an identical interface as the original Cdm class.
    • However, the constructor is different. Instead of passing a Widevine device object, you need to pass information about the API like its host (including port if not on a reverse-proxy), and info about the device like its name and security level.
    • Other than that, once the RemoteCdm object is created, you use it exactly the same. Magic!
    • Any time there's a change or fix to Cdm in this update or any in the future, will also be done to RemoteCdm.
  • New Serve endpoint /set_service_certificate as an improved way of setting (or unsetting) the service certificate.

Changed

  • Cdms constructor now uses more direct values, so you don't have to use the Device class or .wvd files.
    • To continue using .wvd files you must now use Cdm.from_device() instead.
  • You can now unset the Service certificate by providing None to `Cdm.set_service_certificate().

Removed

  • Serve's /challenge endpoint no longer accepts a service_certificate item in the JSON payload.
    • Instead, use the new /set_service_certificate endpoint before calling /challenge.
    • You do not need to set it every time. Once per session is enough unless you now want to use a different certificate.

1.2.1 - 2022-08-02

Added

  • Support SignedDrmCertificate and SignedMessages messages in Cdm.encrypt_client_id(). This is mainly as a convenience for any scripts wanting to encrypt their Client ID with a service certificate manually.
  • All License Keys from Serve's /keys endpoint can now be received by providing ALL as the key type.
    • This adds support for systems needing more than two types of keys from the license, e.g., Netflix MSL.
    • For faster response times it is best to still ask for only CONTENT keys if that's all you need.
  • Serve now has a /close endpoint to close a session. All clients should close the session once they are finished with it or the user will eventually hit a limit of 50 sessions per user and the server will hog memory til it restarts.
  • Serve now verifies that all Devices in config actually exist before starting the server.
  • Serve now responds with a Server header denoting that pywidevine serve is being used, and it's version.
    • This allows Clients to selectively support APIs based on version; verify the API as being supported.

Changed

  • Lessened version pin on lxml from ^4.9.1 to >=4.8.0 to support projects using pycaption.
  • Service Certificate is now saved in the session as a SignedMessage with a SignedDrmCertificate instead of the raw DrmCertificate. The SignedMessage is unsigned as the SignedDrmCertificate within it, is signed. This is so anything inheriting or using the Cdm (e.g., serve) can verify the certificate down the chain and keep it signed.
  • Serve now constructs one Cdm object for each user+device combination so one user cannot fill or overuse the CDM session limit.
  • All of Serve's endpoints now have a /{device} prefix. E.g., instead of /challenge/STREAMING, it's now /device_name/challenge/STREAMING. This is to support the previous change.

Fixed

  • Handle server crash when the session limit is reached in Serve's /open endpoint by returning a 400 error.
  • Serve now correctly updates (or rather now makes a new Cdm object) if a user switches from one Device to another.
    • Previously it would reuse an existing Cdm object, but would forget to switch device if they changed.
    • Note: It does still leave the previous Cdm with the older Device in memory.
  • Handle IOError when parsing bytes as MP4 Box to allow arbitrary data to be made as new boxes in PSSH.get_as_box().

1.2.0 - 2022-07-30

Added

  • New CLI command serve that hosts a CDM API that can be externally accessed with authentication. This can be used to access and/or share your CDM without exposing your Widevine device private key, or even it's identity by enforcing Privacy Mode.
    • Requires installing with the serve extras, i.e., pip install pywidevine[serve].
    • The default host of 127.0.0.1 blocks access outside your network, even if port-forwarded. Use -h 0.0.0.0 to allow remote access.
    • Setup requires the use of a config file for configuring the CDM and authentication. An example config file named serve.example.yml in the project root folder has verbose documentation on available options.
  • Batch migration of WVD files by passing a folder as the path to the CLI command migrate.
  • Strict mode to PSSH.get_as_box() to raise an Exception if passed data is not already a box, as it has been improved to create a new box if not detected as a box already.

Changed

  • Elevated the Development Status Classifier from 4 (Beta) to 5 (Production/Stable).
  • License messages passed to Cdm.parse_license() are now rejected if they are not of LICENSE type.
  • Service Certificates passed to Cdm.set_service_certificate() are now verified. This patches a trivial "exploit" that allows an attacker to recover the plaintext Client ID from a license under Privacy Mode. See https://gist.github.com/rlaphoenix/74acabdd7269a21845e18b621c5860ef.
  • Data passed to PSSH.get_as_box() now supports arbitrary and box data automatically as it tries to detect if it is a valid box, otherwise makes a new box.
  • Renamed the Cdm constructor's parameter pssh to init_data, as that's what the Cdm actually wants and uses, whereas a PSSH is an mp4 atom (aka box) containing init_data (a Widevine CENC Header). The full PSSH is never kept nor ever used. It still accepts PSSH box data.
  • Service Certificate's Provider ID is now returned by Cdm.set_service_certificate() instead of the passed certificate, of which they would already have.
  • The Cdm class now works more closely to the official CDM model. Instead of using one Cdm object per-request having to provide device information each time,
    • You now initialize the Cdm with the Widevine device you wish to use and then open sessions with Cdm.open().
    • You will receive a session ID that are then passed to other methods of the same Cdm object.
    • The PSSH/init_data that used to be passed to the constructor is now passed to Cdm.get_license_challenge().
    • This allows initializing one Cdm object with up to 50 sessions open at the same time. Session limits seem to fluctuate between libraries and devices. 50 seems like a permissive value.
    • Once you are finished with DRM operations, discard all session (and key) data by calling Cdm.close(session_id).
  • License Keys are no longer returned by Cdm.parse_license() and now must be obtained directly from cdm._sessions.
    • For example, for key in cdm._sessions[session_id].keys: print(f"[{key.type}] {key.kid.hex}:{key.key.hex()}").
    • This is to detach the action of parsing a license as just for getting keys, as it isn't. It can be and should be used for a lot more data like security requirements like HDCP, expiration, and more.
    • It is also to detour users from directly using the keys over the Cdm.decrypt() method.
  • Various std-lib exceptions have been replaced with custom exceptions under pywidevine.exceptions.
  • License responses can now only be parsed once by Cdm.parse_license(). Any further attempts will raise an InvalidContext exception.
    • This is as license context data is cleared once used to reduce data lingering in memory, otherwise the more license requests you make without closing the session, the more and more memory is taken up.
    • Open multiple sessions in the same Cdm object if you need to request and parse multiple licenses on the same device.

Removed

  • Direct DrmCertificates are no longer supported by Cdm.set_service_certificate() as they have no signature. See the 3rd Change above. Provide either a SignedDrmCertificate or a SignedMessage containing a SignedDrmCertificate. A SignedMessage containing a DrmCertificate will also be rejected.
  • PSSH.from_init_data(), use PSSH.get_as_box().
  • raw parameter of Cdm constructor, as well as CLI commands as it is now handled upstream by the PSSH creation.

Fixed

  • Detection of Widevine CENC Header data encoded as bytes in PSSH.get_as_box().
  • Custom ValueError on missing contexts instead of the generic KeyError in Cdm.parse_license().
  • Typing of type_ parameter in Cdm.get_license_challenge().
  • Value of type_ parameter if is a string in Cdm.get_license_challenge().

1.1.1 - 2022-07-22

Fixed

  • The -v/--vmp parameter of the test CLI command is now optional.

1.1.0 - 2022-07-21

Added

  • WVD (Widevine Device file) Version 2 bringing reduced file sizes by up to 30%~.
  • New CLI command create-device to create .wvd files (Widevine Device files) from RSA PEM/DER Private Keys and Client ID blobs. You can also provide VMP (FileHashes) data which will be merged into the Client ID blob.
  • New CLI command migrate that uses Device.migrate() and dump() to migrate older v1 Widevine Device files to v2.
  • New Device method migrate() to load an older Widevine Device file format. It is recommended to then use the dumps() method to save it as a new v2 Widevine Device file, which can then be loaded normally.
  • Support SignedDrmCertificate and DrmCertificate messages in Cdm.set_service_certificate(). Services can provide the certificate as a SignedMessage, SignedDrmCertificate, or a DrmCertificate. Only SignedMessage and SignedDrmCertificate are signed.
  • Privacy Mode can now be used in the test CLI command with the -p/--privacy flag.

Changed

  • Moved all .wvd Widevine Device file structures from Device to a _Structures class in device.py. The _Structures class can be imported and used directly, or via Device.structures.
  • Moved the majority of Widevine Device file migration code from the CLI command migrate to Device.migrate(). The CLI command migrate now internally uses Device.migrate().
  • Set Service Certificates are now stored as DrmCertificates instead of a SignedMessage as the signature and other data in the message is unused and unneeded.

Removed

  • Unused Widevine Device file flag send_key_control_nonce from v1 and v2 Structures as it was only used before initial release, and isn't a necessary nor useful flag.

Fixed

  • Correct the type argument name from type to type_ in Device.dump().

Security

  • Even though support for more kinds of Service Certificate Signatures were added, they are still unverified as the signing public key is Unknown.

1.0.1 - 2022-07-21

Changed

  • Moved the License Type parameter from the Cdm constructor to it's get_license_challenge() method.
  • Every License request now uses a unique random value instead of the CDM Session ID.
  • Only the Context Data of License requests are now stored in the Session instead of the full message.
  • Session ID formula now uses a random 16-byte value for both Chrome and Android provisions.

Removed

  • Unused and unnecessary Cdm.raw class instance variable.

Fixed

  • Re-raise DecodeErrors instead of a new ValueError on DecodeErrors in Cdm.set_service_certificate().
  • Creating a new License request no longer overwrites the context data of the previous challenge.

1.0.0 - 2022-07-20

Initial Release.

Security

  • Service Certificate Signatures are unverified as the signing public key is Unknown.