skeyprune(8) on OpenBSD
The text 42ab312e1d88, as OpenBSD 5.4, OpenBSD 5.3, OpenBSD 5.2, OpenBSD 5.1, OpenBSD 5.0, OpenBSD 4.9, OpenBSD 4.8, OpenBSD 4.7, OpenBSD 4.6, OpenBSD 4.5, OpenBSD 4.4, OpenBSD 4.3, OpenBSD 4.2 shipped it.
prune zeroed and old entries from S/Key database