How DRM Encryption Protects Video Content

Digital rights management and DRM encryption go hand in hand; however, understanding how they work together is key to keeping your media protected.

What Is DRM encryption?

DRM encryption occurs when someone uses digital rights management software and sends video content either internally or externally; once transmitted, that content is encrypted so only authorized users will be allowed to view it.

DRM encryption is one of the fundamental ways in which DRM works and operates. DRM encryption uses encryption algorithms and key management techniques to secure intellectual property and digital copyrighted content.

What Is Digital Rights Management and How Does It Work?

Digital rights management encompasses the digital techniques and software strategies used to secure digital content, like video, from piracy and other unauthorized use. DRM is particularly important if you have an online video distribution architecture.

DRM prevents your content from being copied or illicitly used, while also making itself invisible and least intrusive to the customer. DRM is also useful to protect offline copyright where content is packaged in the form of BluRays, CDs, and DVDs.

All DRM content passes through encryption and decryption cycles. But encryption is only the first step in a multifaceted cycle, especially when DRM is applied to video content.

What Is DRM Video Encryption?

The abundance of streaming services and the explosion of podcasts as entertainment mediums have brought video content distribution to an all-time high. This has also heightened the necessity for security around video content and with it the importance of DRM technology.

To protect the integrity of their product, video streaming platforms use encryption to transmit their content. When it comes to audio or video content, the metadata isn’t encrypted; only the data within the segment is.  

Typically, standard content encryption is achieved through AES. This encryption algorithm is used in combination with 128-bit keys and a block cipher.

AES is fast and secure and is widely implemented for encrypting sensitive data. It has been adopted for government computer security, electronic data protection, and cybersecurity. AES is publicly available, with the National Security Agency recommending it and using it for top-secret communications.

How the DRM Encryption Process Works

For DRM video encryption to occur, there needs to be a robust key management system that doesn’t expose private keys to hackers. This encryption has to be supported by a key exchange protocol on the device the video content is being played. This license key taps into either some hardware or software-based security protocol that resides on video streaming’s playback platform, which in turn, enforces the DRM rights.

So, to deploy DRM, the video content is encrypted during packaging with AES 128-bit encryption. A special key protocol is required to facilitate both the encryption and decryption process.

Part of the essence of DRM video content streaming is to ensure the private key is hidden. So, in addition to the AES algorithm, the encryption process is supported by a secure key exchange protocol to protect the 128-bit length symmetric key from hackers.

DRM’s Secure Key Exchange Mechanism

The DRM video “security cycle” starts with encrypting the communication between the license server and the requesting playback software.

• The process is initiated when a customer clicks a button or performs an action to play a video. The action subsequently triggers the video player to request a key from a license server. The keys required for encryption are not stored with or exposed to the customer. 
   
• So, instead of exposing the symmetric key to users, the DRM protection mechanism sends the AES encryption protocol in the header file as metadata, along with the video content. 
   
• Next, this metadata is “reverse-engineered” to create a license request by a piece of software that resides on the device or browser known as Content Decryption Module. When the device/browser receives the metadata, the CDM creates another request, but this time, it is sent to the remote license server. 
   
• A detailed license is returned along with the content keys necessary for the CDM to decrypt the content. When this process is complete, the video content becomes available and ready for the user to play. 
   

Moreover, it’s important to note that throughout this DRM process, both the license information and the license request aren’t accessible to the user. The process is handled by an API called Encrypted Media Extensions API which provides the interfaces to control the playback of content.

After video content is encrypted and packaged, it is subjected to various DRM protection technologies to ensure it provides device compatibility.

These are the most common DRM technologies currently used:

• Apple’s FairPlay: This scheme uses cipher block chaining encryption. This is the only option available for Apple devices, such as the Safari browser on OS X, AppleTVs, iPhones, and iPads.
• Google’s Widevine: Initially developed by Widevine Technologies, Widevine was later bought by Google. It is used natively on Android devices, on web browsers such as Chrome and Edge, and devices like Smart TVs and Roku.
• Microsoft’s PlayReady: Microsoft developed this technology; therefore, it is supported by Windows and associated products like Xbox, Windows Phone, Edge browsers, and so on.
   

The licensing information delivered by Widevine or FairPlay differs from that of PlayReady, and vice versa. However, compatibility is assured by using the Common Encryption Scheme (CENC). This scheme ensures there’s a common format used by all DRM systems. It does this by specifying standard key mapping methods and encryption for the related metadata required to decrypt protected video and audio streams.

CENC is neither proprietary nor tied to any specific DRM system. It covers ISO base media file format files and MPEG systems technologies to provide neutrality by allowing various key mapping methods for different digital rights and key management systems.

By permitting multi-DRM and key management systems to decrypt the same file and video content, CENC expands the range of reachable clients from one content stream.

Why Is DRM Encryption Better than Standard Encryption?

While encryption is a crucial component in DRM, it’s only a single step in the holistic strategy to manage and protect digital rights.

DRM is a holistic concept that encompasses the strategies to protect the rights of digital content, with encryption as the first step in its deployment. It’s an important phase since the encryption component provides the ability to create rights around the content. The license key that’s subsequently sent to the video playing device, which is used in conjunction with the device’s security, expresses and enforces those rights.

DRM encryption is better than standard encryption because it’s more ideally suited to protect media and entertainment assets such as video content. It involves a more intricate process geared to both protecting your copyright without degrading the user experience of your customers.