alt Hacker NewsNot sure how many people feel like this, the risk in plain sight is a lot easier to handle than the risk hiding under the layers. You can keep shifting the storage for the key, one way or another you have to open up a channel to access to key or use the key. That channel would then become the vulnerability target.
To prove possession of a private key, one needs only to sign something with that key (this is how SSH key auth works). This is how things like the macOS Secure Enclave operate - the private key is stored in a separate hardware chip that only exposes an interface to sign something with that key, never to actually present the key. To obtain the key would require having physical access to the computer, ripping it open, and performing advanced deconstruction and analysis of that chip.