On Wed, Dec 16, 2020 at 09:41:42AM -0800, Chang S. Bae wrote: > When the system state switches to these sleep states, the internal key gets > reset. Since this system transition is transparent to userspace, the > internal key needs to be restored properly. > > Key Locker provides a mechanism to back up the internal key in non-volatile > memory. The kernel requests a backup right after the key loaded at > boot-time and copies it later when the system wakes up. > > The backup during the S5 sleep state is not trusted. It is overwritten by a > new key at the next boot. > > On a system with the S3/4 states, enable the feature only when the backup > mechanism is supported. > > Disable the feature when the copy fails (or the backup corrupts). The > shutdown is considered too noisy. A new key is considerable only when > threads can be synchronously suspended. Can this backup key be used to decrypt the encoded AES keys without executing the keylocker instructions on the same CPU? - Eric
