Regarding the optional OpenSSL integration for the portable version

[Scott Neugroschl]

>NetBSD and FreeBSD (as of 10.0) both use a sysctl, just like OpenBSD. Linux also has an obscure sysctl which pulls directly from the internal CSPRNG. So all of these will work in a jail without /dev or /proc.

>OS X still seeds itself from /dev/urandom in its arc4random implementation, as it inherited FreeBSD's old code. Solaris sadly only has /dev/urandom.

And then there are those implementations that have to use PRNGD because there's no built-in source of randomness.