[simias]

>I don't think Windows gives an administrator account unfettered access to the full RAM, no.

Are you sure? Typically root has access to the full RAM on an unx system. Unless this is linked to a hardware TPM module I'm not sure why and how it would be protected. Maybe I'm wrong to assume that Windows Administrator == unx root?

Anyway, if the OS has a way to hide some of its state from even the admin then surely it could use it to hide the unencrypted SSH key in RAM instead of hiding the key-to-the-registry-key? My main argument is that at some point if the OS doesn't want to prompt the user for a password it must have access to the private key one way or an other, so I'm not convinced that Windows is more (or less) secure than Linux in this situation.