Implement mTLS in Nextcloud Desktop Client

[WinkelB]

mTLS enhances authentication and data security by requiring both client and server to present valid certificates. This prevents unauthorized access and protects against impersonation, ensuring data confidentiality and compliance with regulations. By integrating mTLS, Nextcloud Windows app would fortify its security and meet evolving threats head-on.

[functionpointer]

#6584

[WinkelB]

I'm not sure why, but I tested it yesterday due to some movement in the iOS issue, and it worked flawlessly. I logged out and completed the login flow via webauth. Can someone else confirm?

Nextcloud Hub 8 (29.0.2)
Nextcloud Desktop-Client 3.13.0
using Cloudflare mTLS
my Rule looks like this so webdav and caldav are stil working
(not cf.tls_client_auth.cert_verified and http.host in {"nc.**"} and not http.request.full_uri contains "https://nc.**/remote.php/dav/principals/users/" and not http.request.full_uri contains "https://nc.**/remote.php/dav/calendars/")