The current man page for FreeBSD random (4) is at http://www.freebsd.org/cgi/man.cgi?query=random&apropos=0&sektion=4&manpath=FreeBSD+9.2-RELEASE&arch=default&f

The current man page for FreeBSD random (4) is at http://www.freebsd.org/cgi/man.cgi?query=random&apropos=0&sektion=4&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html http://www.freebsd.org/cgi/man.cgi?query=random&apropos=0&se... whose HISTORY section reads: A random device appeared in FreeBSD 2.2. The early version was taken from Theodore Ts'o's entropy driver for Linux. The current software implementation, introduced in FreeBSD 5.0, is a complete rewrite by Mark R V Murray, and is an implementation of the Yarrow algorithm by Bruce Schneier, et al. The only hardware implementation currently is for the VIA C3 Nehemiah (stepping 3 or greater) CPU. More will be added in the future. dlitz's worry was about initial entropy, which is why he wanted his ideal random device to block initially - this makes a lot of sense. That said, I guess if you are worried about sophisticated attackers [+] getting to see very long stretches of output from your random device, you might want to ensure you are periodically injecting some fresh entropy in there. This should be ensured in the system, so the luser can just read /dev/urandom, but it should be possible to check that the system has fresh enough entropy. FreeBSD's interface seems better suited for this than Linux's. [+] Let's think of the topical "sufficiently sophisticated attacker", who might have secret knowledge of problems with the CSPRNG we use.