HLS Encryption and DRM Techniques for Secure Video Delivery

The company aims to increase potential user scale, user value, and revenue by offering video courses that build financial awareness and trust, making video protection a critical component of the user conversion funnel.

Common video encryption solutions in online education are often insufficient, leading to piracy where paid videos can be purchased cheaply on other platforms.

Anti-leech technology attempts to prevent downloads by allowing only online playback, but it can be bypassed by mimicking browser requests and forging referer headers.

HLS encryption (m3u8 segment encryption) uses AES encryption, which is secure in theory but vulnerable because the decryption key can be easily obtained if not properly protected.

Private per‑frame encryption algorithms provide stronger security by requiring a proprietary player, though reverse engineering can still expose the algorithm.

Digital Rights Management (DRM) offers a more robust solution, with major schemes such as Microsoft PlayReady, Google Widevine, and Apple FairPlay, each tailored to specific operating systems and browsers.

DRM can be implemented via multiple schemes, but custom requirements led to a HLS‑based DRM implementation.

In HLS encryption, the original video is segmented, each segment is encrypted (typically with AES‑128), and an index (M3U8) file is generated to reference the segments.

HLS, introduced by Apple, delivers media over HTTP by splitting streams into small TS segments referenced by an M3U8 playlist.

The M3U8 file contains an EXT‑X‑KEY tag specifying the encryption method, URI for the key, and IV; the key can be retrieved and used to decrypt the TS segments via Media Source Extensions.

Key encryption protection methods include protecting the key URL, using authenticated cookies, and encrypting the key itself before delivery.

To strengthen protection, the solution combines these methods: token‑based validation for key URIs, double encryption of index and key files with a modified client player, and asymmetric encryption of the key using a public‑private key pair.

Because Apple does not support Media Source Extensions, custom encryption for Apple HLS requires FairPlay, necessitating two encryption schemes to achieve cross‑platform protection.

The article concludes that further topics such as dynamic encryption, watermarking, and H5 screen‑recording protection remain to be explored.