envoyproxy/envoy

Dynamic Per-Connection Certificates for QUIC in Envoy

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#42,063 opened on Nov 17, 2025

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enhancementhelp wanted

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Description

Hi all,

I’m exploring a setup where Envoy should present different TLS certificates on a per-QUIC-connection basis, depending on the SNI. Because some clients use ECH, the inner SNI may be encrypted, id like to instead infer the intended SNI from dynamic metadata we set at the listener filter.

A couple of questions:

Is there a recommended approach for selecting certificates dynamically for QUIC based on per-connection metadata (rather than the SNI visible to Envoy)?

Is there any experimental support or planned API to give the QUIC handshake access to FilterState, dynamic metadata, or similar Conn-level information during certificate selection?

Any guidance, design pointers, or examples would be greatly appreciated. Thanks!

Contributor guide

Research direction
Investigate Envoy's QUIC handshake configuration and check if FilterState or dynamic metadata can be accessed during certificate selection. Look for any existing API or workarounds in the codebase or discussions.
Tech stack
cpp
Domain
backendsecurity
Issue type
Research
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
C++
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40