I've task where we need to compress and protect attachments and some log files. I did not look in Lotus Script area at all (as I'm sure it would be not possible or to difficult to do such thing). So I started to look for free RAR/ZIP Java libraries that will have what I need (compress and password).
I was surprised a bit, RAR does not have such API at all, but ZIP has already built in Domino library that allow us to zip files but... not to set password (at least I did not find).
So after couple minutes in google I've found only one free Java library that could zip files with password: http://code.google.com/p/winzipaes/
There were no problems during implementation, library is well described.
Java, Java and Java :)