How to set a temporary truststore for WinHttp

Hi all,

we use WinHttp with SSL enabled for secure client/server connections. We have a private PKI and need to import our CA certificate into an appropriate truststore, so the SSL handshake runs through. Preparing a truststore outside the application is no option. We started with temporarily importing the CA certificate into the system certstore, but of course this fails for users without admin rights. We didn't like this approach, because it side effects all other applications accessing the system truststore, but saw no other choice to achieve our goal.

My questions are:
- can we create a temporary truststore and tell WinHttp to use this truststore for the SSL handshake?
- if not, what other choice do we have?

Thanks for your help,
Emil