Watermarking solutions are extensively being used today to secure video content from illegal distribution. These approaches can be implemented either on the client side, server side, or a combination of the two (“hybrid”).
In the client-side watermarking approach, the content server sends a unique content copy to all users through broadcasting channels without the need to generate unique watermarking copies. The use of a broadcasting system eliminates bottlenecks associated with computational burden and bandwidth requirements which are generally faced on the server side and network node. Client-side solutions are securely integrated with media players or embedded in lightweight and versatile hardware. Further, the watermark extraction process can be performed within a minute (compared to up to 15 minutes in server-side applications) making them highly suitable for preventing live sports streaming piracy.
However, since client devices cannot be trusted completely, there is a need to devise solutions that prevent malicious users from accessing the original content or inserting the watermark. Secure video watermarking embedding is a novel approach that has been developed to address this concern. Here, while the server transmits the same encrypted version of the original asset to all the clients, a client-specific secret is used to decrypt the content as well as embed a personalized watermark, thereby creating a uniquely watermarked version of the content.
In addition, client-side watermarking also exposes the watermarking logic which can be tampered with to bypass watermarking. This can be achieved by reverse-engineering the exposed JavaScript code or by modifying the DOM (document object model). DOM modification can be done by changing, introducing, or removing visual elements in the application.
Therefore, additional tamper-proofing solutions must be employed to secure DRM protected content. To tackle JavaScript reverse engineering, the agent’s code must be protected by using JavaScript obfuscation along with anti-debugging and anti-tampering techniques. They break the web layer in the event of an attack and thereby prevent code analysis. DOM tampering, on the other hand, can be addressed by real time monitoring of the DOM to detect and block any kind of watermark tampering attempt. In addition, web page monitoring solutions can be employed to detect modifications in the DOM (changes to HTML elements or CSS properties) irrespective of the delivery mechanism.
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