Videoconference Liveness Protocol With Clock Drift Correction
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Solution Overview
Problem
Videoconferencing systems often fail to enforce liveness requirements, allowing attackers to arbitrarily delay communications, which poses a threat to the security and integrity of real-time videoconferences.
Innovation Solution
Implement a liveness protocol that enforces a liveness constraint by transmitting heartbeat messages with a send time stamp, allowing participant devices to compute an estimated send time and maintain or disconnect from the conference based on clock drift correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liveness protocol is implemented to enforce liveness constraints, then the security and integrity of the videoconference is improved, but the device complexity increases
Solution Approach 1:
The protocol employs heartbeat messages that continuously feedback the current time from the leader device to participant devices. This feedback mechanism enables participants to verify liveness by comparing the current time with the last known time, allowing automatic disconnection if the time difference exceeds a threshold, thus ensuring security without requiring complex continuous monitoring systems
Solution Approach 2:
Each participant device independently performs liveness verification using its own local clock and the heartbeat messages received from the leader. The verification process is self-contained at the participant level, with each device autonomously determining whether to disconnect based on the time difference calculation, eliminating the need for centralized control or complex inter-device coordination
2Measurement precision
If clock drift correction is implemented to account for time differences between devices, then the accuracy of liveness verification is improved, but the measurement precision requirements increase
Solution Approach 1:
The protocol introduces an intermediary approach by using the leader device as a reference point for time synchronization. Instead of requiring precise synchronization between all participant devices, the system uses the leader's timestamped heartbeat messages as an intermediary reference that all participants can reliably compare against their local clocks, simplifying the synchronization requirements while maintaining verification accuracy
Solution Approach 2:
The protocol changes the parameter approach from requiring absolute time synchronization to using relative time differences. By focusing on the time difference between current time and last known time rather than absolute clock accuracy, the system accommodates clock drift between devices while maintaining sufficient precision for liveness verification through the heartbeat mechanism
3Reliability
If heartbeat messages with timestamps are transmitted to enforce liveness, then the reliability of real-time communication is improved, but the loss of time increases
Solution Approach 1:
The protocol uses periodic heartbeat messages transmitted at regular intervals from the leader device to participant devices. This periodic action allows liveness verification to be performed continuously without requiring constant communication, reducing the time overhead compared to continuous verification while maintaining reliable liveness detection through the rhythmic heartbeat signals
Data Source
AI summary
In one example, a participant device can receive a heartbeat message from a leader device associated with a videoconferencing meeting. The participant device can correspond to a participant in the videoconferencing meeting. The participant device can determine a current time, extract a send time from the heartbeat message, and determine an offset value indicating a difference between a first clock of the participant device and a second clock of the leader device. The participant device can then determine a last heartbeat message time based on the send time and the offset value. Based on the current time and the last heartbeat message, the participant device can determine whether to disconnect from or stay connected to the videoconferencing meeting.