TLS with Client Authentication using private key from Windows store

[Ferenc Gerlits via openssl-users <openssl-users@xxxxxxxxxxx>]

Hi,

I am trying to use openssl to implement a client-side TLS connection with Client Authentication on Windows, using a non-exportable private key stored in the Windows Certificate Store.  Currently, our code can use a private key stored in a local file, and if the key in the Windows store was exportable, I could export it and use it in the existing code.  But the key is non-exportable, which is a problem.

Does anyone know how to do this?

So far, I have found suggestions to use the CAPI engine (eg. https://groups.google.com/g/mailing.openssl.users/c/_rdJLc7emAY?pli=1), but no examples of how to do that, and also some tickets (eg. https://github.com/openssl/openssl/issues/12859) which say that the CAPI engine does not work with TLS >= 1.2 on openssl 1.1.1, so that doesn't look like a good solution.

Any help would be appreciated!

Thank you,

Ferenc