The design we describe satisfies the goals we enumerate in Section III-A.
The PEK serves as the application secret that ensures confidentiality of data produced during private execution (S1), (S2). The PRIVEXEC-enabled OS isresponsible for protecting the confidentiality of the PEK,ensures that the user cannot be expected to know the value of individual PEKs, and prevents private processes from inadvertently leaking sensitive data via IPC channels to other processes (S3), (S4). Destroying the PEK after a private execution has ended ensures that any data produced cannot feasibly be recovered by anyone, including the user (S5).