When it comes to the world of over-the-top (OTT) content, the security of video assets is of the utmost significance. This is because there is a significant demand for premium material in the grey market, where individuals want to watch popular TV shows and movies without paying for access to them. It has an effect on the amount of money that industry leaders such as Netflix, Amazon Prime, Disney+, and others generate in revenue because these companies invest a significant amount of money in order to gain exclusive distribution rights for premium content.
OTT players encrypt video streams with multi-DRM services and manage DRM licences from industry heavyweights such as Google’s Widevine, Apple’s FairPlay, and Microsoft’s PlayReady. These majors include Apple Inc. A reliable multi-DRM service will also safeguard video files by adding a video watermark. This allows the company to more easily identify places of potential leakage and take corrective measures.
The AES-128 encryption standard is used by many players to encrypt video material; nevertheless, the security of the decryption key is a challenge for these players. Even if the encryption standard is of the highest calibre, content leakage and unauthorised usage of video streams may still occur if the decryption key is not properly safeguarded. OTT players have turned to multi-DRM services as a solution to this issue.
Enhanced Security Via Digital Rights Management
The distribution and administration of encryption and decryption keys, in addition to backend licencing servers, are all functionalities of digital rights management, also known as DRM. The Advanced Encryption Standard (AES) is the encryption method that is utilised by commercial DRM systems. It entails encrypting the premium material so that it can only be read with a decryption key that is issued by a third-party digital rights management provider that has been selected by the OTT platform. Because the same key is used for both encryption and decryption, this approach is known as a symmetric key algorithm. The licence server is where the encryption keys are stored for safekeeping.
When encrypting their videos, content owners typically turn to a cryptographic key with 128 bits of AES. The final consumer is going to need to utilise the same key in order to play back the video material. The content can only be accessed by those users who have the key in their possession. The server belonging to the multi-DRM service provider checks to see if the user and the device in question are approved before it sends back a licence response containing a decryption key.
Since digital content needs to be encrypted to prevent it from being misused or any illicit or unauthorised playback, it should be packaged in a format that is compatible with other media, such as MPEG-DASH or HLS. This ensures that the content can be decrypted when it is needed. Both MPEG-DASH and HLS are examples of streaming protocols that are built on top of HTTP. The source files are encoded into various adaptive streaming formats via the cloud encoding system. The files are encrypted using encryption keys received from many DRM vendors by the encoder.
The multi-DRM packager will send a request for an encryption key to the DRM system, such as Google’s Widevine, in order to encrypt any digital material. When the DRM system has finished providing the encryption key, that key will immediately be linked to the media content ID. There are circumstances in which the encryption keys are generated within the packager itself before being transmitted to the DRM system for the purposes of storage and distribution to the users. The material is later encrypted by the packager with the use of the encryption key.
Before the client can play back the content, it must first have its encryption broken. The client is granted access to the decryption key for the specific content ID that was utilised throughout the encryption process of the video through the DRM system. The Content Decryption Module (CDM) is a piece of proprietary software that is either an integral part of the device or the browser. It is responsible for decrypting data. Every device that is compatible with Encrypted Media Extensions (EME) has a CDM built into it. It is responsible for decrypting the video material and making it accessible for usage by the player.
Even though it is technically possible for a studio or content producer to use AES protection for their own content on their own, it is possible that they will not be able to plug the hardware-based leakages or stop the insecure transmission of AES keys between devices or between the server and the client device. When a multi-DRM solution secures video content with an AES layer, it closes this loophole in the security system.
The significance of both AES-CTR and AES-CBC
The most prominent digital rights management (DRM) systems have moved to implement Common Encryption (CENC), a standardised mechanism for providing digital content protection. A single content file-set can be encrypted using CENC just the one time, and then it can be distributed across several devices or platforms, each of which may use a different digital rights management (DRM) system. The CENC encryption standard is compatible with both the cypher block chaining (CBC) and counter (CTR) modes of operation.
The Advanced Encryption Standard (AES) is the most popular algorithm for block encryption. The processes of encrypting and decrypting data are referred to as block cypher protocols. In order to generate a block of ciphertext with the same dimensions as the plaintext block, the plaintext block is first used as a single block. There are 128 individual bits that make up the encryption block. When the plaintext does not provide enough information for a block, a few methods can be used to pad it out; if you employ the CBC mode, you can protect yourself from an attack that uses padding. CTR mode, cypher feedback mode (CFB), and output feedback mode (OFB) are all examples of modes that can be used to support a stream of plaintext in addition to AES mode. Although both AES-CTR and AES-CBC, which are used for the encryption of digital material, serve the same purpose—namely, the encryption of digital content for security and the decryption of digital content via DRM licencing by a player—they are not always compatible with one another. For example, HLS and all Apple devices only support the AES-CBC encryption algorithm.
In order to prevent the video file from being played back, the encryption process involves the use of an algorithm. This is accomplished with the assistance of a key, which is applied in conjunction with the algorithm to accomplish the task of encrypting as well as decrypting the digital content. Every video as well as every asset component, such as audio, standard definition video, and high definition video, uses its own unique key. Encrypting or decrypting a video is an example of symmetric cryptography because of this.
The Benefits of Using Multiple DRMs
A DRM solution allows for the streaming of video content as well as the ability to replay in an environment when the user is not connected to the internet. It handles digital rights management (DRM) packaging of the source content and offers this as a cloud-based solution as a service (SaaS) facility to digital content producers and OTT providers as a service that it provides. It often comes pre-integrated with major cloud services, such as AWS Elemental Media Services through its SPEKE API. This is the case in many circumstances. This brings to light the protocol that should be used for communication between those who encrypt and package media assets and those who distribute DRM keys.
