feat: Add support for AES-encrypted video offline playback

[Balamurugan-Testpress]

• Offline playback failed for AES-protected videos because the player did not fetch, persist, or serve encryption keys when offline.
• Added AES content-protection support with secure key storage during download and key cleanup on video deletion.
• Persisted protection type in offline schema for proper key resolution.

[gemini-code-assist]

Summary of Changes

Hello @Balamurugan-Testpress, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the video playback capabilities by introducing robust support for AES-encrypted videos in offline mode. It resolves a critical issue where such videos could not be played without an internet connection, by implementing secure storage and retrieval mechanisms for encryption keys. The changes ensure a seamless and secure offline viewing experience for users of AES-protected content.

Highlights

• AES Offline Playback Support: Implemented full support for offline playback of AES-encrypted videos, addressing previous failures where encryption keys were not fetched, persisted, or served when offline.
• Secure Key Storage: Introduced a new EncryptionKeyRepository to securely store AES encryption keys using Keychain during video download and ensure their cleanup upon video deletion.
• Content Protection Type Persistence: Modified the LocalOfflineAsset model to persist the contentProtectionType (DRM or AES), enabling the player to correctly resolve and apply the appropriate key management strategy during offline playback.
• Refactored Key Fetching Logic: Updated the ResourceLoaderDelegate to intelligently handle key requests, distinguishing between online fetching via ContentProtectionAPI and offline serving from the EncryptionKeyRepository.

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Changelog

• Source/Constants/ContentProtectionConstants.swift
  • Added new file to define ContentProtectionType enum and constants for encryption key paths and endpoints.
• Source/Database/Models/OfflineAssetEntity.swift
  • Added contentProtectionType property to LocalOfflineAsset to store the type of content protection.
  • Updated initializers and conversion methods to include the new contentProtectionType.
• Source/Database/TPStreamsDownloadManager.swift
  • Initialized EncryptionKeyRepository for managing encryption keys.
  • Modified startDownload to pre-fetch and save AES encryption keys for AES-encrypted videos.
  • Updated createLocalOfflineAsset to store the content protection type.
  • Added preFetchEncryptionKey and saveEncryptionKey methods to handle AES key fetching and storage.
  • Integrated deleteEncryptionKeys calls into cancelDownload and deleteOfflineAsset for key cleanup.
  • Added a new private method deleteEncryptionKeys to remove stored encryption keys.
• Source/Managers/EncryptionKeyRepository.swift
  • Added new file to provide a secure repository for saving, retrieving, and deleting encryption keys using Keychain.
• Source/Managers/ResourceLoaderDelegate.swift
  • Refactored the delegate to support both online and offline key fetching.
  • Added isPlaybackOffline and offlineAssetId properties to manage offline playback state.
  • Implemented serveOfflineEncryptionKey to retrieve keys from the EncryptionKeyRepository for offline content.
  • Updated setEncryptionKeyResponse to handle optional key data.
• Source/Network/ContentProtectionAPI.swift
  • Added new file to handle API requests for fetching AES encryption keys.
• Source/Network/Models/Video.swift
  • Added contentProtectionType property and isAESEncrypted computed property to the Video struct.
• Source/Network/Parsers/StreamsAPIParser.swift
  • Updated parseVideo to correctly parse and assign the contentProtectionType.
• Source/Network/Parsers/TestpressAPIParser.swift
  • Updated parseVideo to correctly parse and assign the contentProtectionType based on drm_enabled or encryption_enabled.
• Source/TPAVPlayer.swift
  • Modified the offline initializer to correctly instantiate ResourceLoaderDelegate with offline playback parameters.
• Source/TPStreamsSDK.swift
  • Incremented the Realm database schema version from 4 to 5.
• Source/Utils/VideoURLParser.swift
  • Added new file with a utility struct to extract video IDs from URLs.
• StoryboardExample/MainViewController.swift
  • Updated sample assistId and accessToken for testing purposes.
• iOSPlayerSDK.xcodeproj/project.pbxproj
  • Added new file references for VideoURLParser.swift, ContentProtectionAPI.swift, EncryptionKeyRepository.swift, and ContentProtectionConstants.swift to the Xcode project.

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[gemini-code-assist]

Code Review

This pull request introduces support for AES content protection alongside existing DRM, involving the addition of a ContentProtectionType enum and related constants. The LocalOfflineAsset model is updated to store the contentProtectionType, though a reviewer suggested a more robust storage type than an optional string. A new EncryptionKeyRepository is implemented to securely save and retrieve AES encryption keys from the Keychain. The TPStreamsDownloadManager is enhanced to pre-fetch and manage these AES keys for offline content, including their deletion when assets are removed, with a reviewer questioning the dual saving of keys for assetId and videoId. The ResourceLoaderDelegate is refactored to handle both online and offline key requests, utilizing a new ContentProtectionAPI for online fetching and the EncryptionKeyRepository for offline keys. A new VideoURLParser is introduced to extract video IDs from URLs, but reviewers noted potential brittleness in its heuristic and the reliance on url.lastPathComponent for offline key identification. Additionally, the Video model and API parsers are updated to incorporate the new content protection type, and the Realm database schema version is incremented.

[Balamurugan-Testpress]

/gemini review

[gemini-code-assist]

Code Review

This pull request successfully adds support for offline playback of AES-encrypted videos. The changes are well-structured, introducing secure key storage using Keychain, updating the data models, and creating a new API for fetching keys. I've made a few suggestions to improve code clarity and performance, such as removing an unused parameter and using a lazy sequence for key lookups. Overall, this is a great enhancement.

[Balamurugan-Testpress]

/gemini review

[gemini-code-assist]

Code Review

This pull request adds support for offline playback of AES-encrypted videos. The changes are comprehensive, introducing logic to fetch, securely store in the Keychain, and serve encryption keys. New components like EncryptionKeyRepository and ContentProtectionAPI are well-designed. My review highlights a critical issue regarding a mismatch in key identifiers that could prevent the feature from working as intended, along with a couple of medium-severity suggestions to enhance error handling in the new Keychain repository.

[Balamurugan-Testpress]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces significant functionality for AES-encrypted video offline playback. The changes are comprehensive, touching data models, download management, network layers, and the player itself. The implementation of key fetching, secure storage in the Keychain, and manifest hardening for offline playback is well-thought-out. I've identified a few areas for improvement regarding error handling, code clarity, and redundancy, which are detailed in the specific comments. Overall, this is a solid implementation of a complex feature.

[harinath01]

I think we can extract the keychain manipulation logic into a separate util class.

[harinath01]

If we extract the keychain into separte util class, we don't need the repository class i think.

We could handle the repository logic in this class itself.