For those unaware, "PHK" is:
* https://en.wikipedia.org/wiki/Poul-Henning_Kamp
Amongst other things (including jails), he invented the MD5crypt algorithm (originally for FreeBSD) as an alternative to the original DEScrypt of Unix:
* https://en.wikipedia.org/wiki/Crypt_(C)#MD5-based_scheme
Nowadays probably most well-known for creating Varnish:
* https://en.wikipedia.org/wiki/Varnish_(software)