- Extend sbin/pefs so that it creates checksum file with dummy tags/tweaks which is then read during pefs_mount. pf_nodes are properly marked upon creation. 

- Extend sbin/pefs so that it accepts secret key from userland and that proper tags/tweaks are created for checksum file. At this point test with one HMAC algorithm. 

- Integrity checks in Vnode Operations. 

- Implement authentication checks for checksum files during mount. 

- Extension of securelevel and perhaps rtld.