Group Call End-to-End Encryption and the Challenges of Encrypting Large Calls

on YouTube ↗17m

" summary

Group calls use an SFU so media is routed server-side but is encrypted end-to-end with SFrame and per-sender symmetric sender keys (AES) negotiated via public keys; a 100-person join can mean a 25 kilobyte public key blob and public-key decryption latency that grows linearly (2–8 seconds observed for 100 participants). Leaving triggers a quadratic key churn (≈10k key messages for 101 users, ~640 KB at 64 bytes each). Mitigations: cache public keys, multithread/key batching, prioritize active-speaker keys, ratchet on join, and send keys over high-throughput media channels.

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" chapters (3)

1. 0:00Introduction
2. 1:03Encryption Architecture
3. 7:36Scaling Group Calls

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