dnssec-keygen(8) on macOS
The text a2591240627b, as Mac OS X 10.5.6, Mac OS X 10.5.5 shipped it.
DNSSEC key generation tool
Flags it lists
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-a -
-b -
-c -
-e -
-f -
-g -
-h -
-k -
-n -
-p -
-r -
-s -
-t -
-v