Hello,

I've recently been involved in producing PoC, which utilizes OP-TEE
to produce proof of a secret key possession. That is used during tunnel
establishment by OpenVPN.

In case someone finds it interesting, for example as kind of "real-world"
use case of OP-TEE, then details are described here:
https://www.amongbytes.com/post/20210112-optee-openssl-engine/
and code is here:
https://github.com/henrydcase/optee_eng

The actual PoC used post-quantum schemes integrated into TEE OS and TF-A
(secure boot). Those two points are not described really described for brevity
(and probably there is low interest anyway).

Kind regards,
Kris