Ah, I see that Secretive is a victim of feature creep. I think it still can use the SE to store the private key, but it also has more ways to do it.

This is the initial inspiration for Secretive: https://github.com/sekey/sekey - it uses the SE to generate and store the actual private key, so it never leaves the machine. Hence its limitations.

Again - I could be really wrong about Secretive. Sadly their documentation dont make it very clear and I myself don't have enough time to actually to go read the code and figure out how it works exactly.