In Chromium and in nearly every major webbrowser when you open a site, which requires you to sign in using a certificate (e.g. Microsoft Azure Portal), you will get a dialog, where it is possible for you to choose a certificate out of a list of certificates available.

in QtWebEngine, there is no such feature, instead the connection will be closed with an error, stating a client certificate is missing.

I already tried to implement this feature on my own in the custom chromium stack of QtWebEngine, but it seems, the Chromium-SSL stack used is completely different and is missing much of the HSM encryption code, which is included in Chrome/Chromium.

A possible (from my view) solution, after copying back all the HSM-related code into the chromium stack, could be to implement a signal, which contains a list of metadata of the certificates (e.g. QSSlCertificate) and the possibility to reply back, once the UI thread has finished its work. A similiar approach was also taken in the chromium code.