microsoft/msquic

Allow CA certificates to be loaded from memory instead of file

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#5,715 opened on Jan 14, 2026

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feature requesthelp wanted

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Description

Describe the feature you'd like supported

When using the OpenSSL backend, it is possible to provide a custom CA certificate file. This is a very handy feature, but only allowing CA certificates to be loaded from a file can add complexity on some platforms and potential security issues. We would prefer to be able to pass a pointer to memory block instead, which can for example be some static memory inside the executable.

Proposed solution

Here is a suggested patch that adds a new flag to treat the existing CredConfig->CaCertificateFile as the content of a CA certificate instead of the path to a CA certificate file. Since this file contains plaintext, not binary data, it is safe to use a null-terminated C string here, and hence it is not required to extend the CredConfig structure.

I cannot and will not sign the Microsoft CLA to submit this feature as a PR, so feel free to use this patch as a starting point in whatever way you like.

memory-ca-file.patch

Additional context

No response

Contributor guide

Research direction
Review the attached patch in the issue to understand the proposed changes to CredConfig and the OpenSSL backend. Implement a new flag to load CA certificates from a memory buffer instead of a file path.
Tech stack
c
Domain
securitynetworking
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
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.
Clear
Prerequisites
COpenSSL
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60