Lawful Interception Codec Matching for Encrypted VoIP Media
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Solution Overview
Problem
Current lawful interception methods in mobile communications networks, particularly in IMS-based VoIP systems, face challenges in accurately identifying network nodes for call content interception and managing codec types and encryption keys, leading to difficulties in delivering intercepted media to law enforcement agencies.
Innovation Solution
The method involves identifying network nodes that provide call content interception, determining the codec type used at these nodes, and sending appropriate codec types and session description protocol security keys to the delivery function, depending on the interception location within the network, ensuring that intercepted call content is either encrypted or decrypted as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If codec type information is determined at the network node for call content interception, then the accuracy of intercepted media delivery is improved, but the device complexity increases due to additional determination and matching functions
Solution Approach 1:
The patent introduces an intermediary function that acts as a bridge between the network node performing interception and the delivery function. This intermediary handles the codec type determination and matching, allowing the core interception system to remain simple while achieving accurate codec identification through the mediating component that translates between different codec representations.
2Adaptability or versatility
If session description protocol security description keys are sent to the delivery function, then the ability to deliver encrypted intercepted media is improved, but the loss of information increases due to key management overhead and potential key leakage risks
Solution Approach 1:
The patent applies local quality by making the security key handling adaptive to the specific interception scenario. Session description protocol security description keys are sent to the delivery function only when the intercepted media requires encrypted delivery, rather than universally. This localized approach enables encrypted media delivery capability where needed while avoiding unnecessary key management overhead and information loss in scenarios where encryption is not required.
3Measurement precision
If the location of call content interception is determined at the network node, then the precision of media delivery is improved, but the difficulty of detecting and measuring increases due to multiple possible interception points
Solution Approach 1:
The patent segments the network into distinct functional zones with defined interception capabilities. By dividing the network infrastructure into specific nodes (such as media gateways, border gateway anchors, and delivery functions) with clearly assigned roles, the system achieves precise location identification without the complexity of continuously monitoring all possible interception points. Each segment handles determination of its own interception location, simplifying the overall measurement process.
Data Source
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AI summary
Certain embodiments of the invention generally relate to lawful interception of communications for IP Multimedia System-based (IMS- based) voice over IP (VoIP). For example, some embodiments relate to interception of communications including interception for encrypted, transcoded media. A method may include identifying a network node that provides call content interception. The method may also include determining a codec type used at a location of the call content interception at the network node. The method may further include sending a matched codec of the codec type used at the location of the call content interception at the network node to a delivery function in the communications network.