OpenBSD is a free 4.4BSD based UNIX-like OS. Its goals are correctness, stability, and security. It probably has some of the best built-in cryptography support of any Free OS.
Its web site is at http://www.openbsd.org/
The Java in OpenBSD situation is a little rough, since there are no native ports of Sun's JDK, but it's getting better. FreeBSD JDK 1.1.8 and Blackdown JDK 1.2 are both in ports-current as of 3/1/01, as are JFC/Swing, HotJava, Kaffe, guavac, and various other libraries, apps, and tools. Jikes builds and runs fine in OpenBSD, though it doesn't seem to be in ports.
If you want to work on JJOS, you'll probably have to install nasm (it's in ports) and build an ELF cross compiler. There are most likely other issues too... I haven't tried too hard yet, but I'll post more info here when I do.
-- MichaelLothian - 01 Mar 101