4 ms·
As mentioned by the article that's already the default behaviour of getrandom() and the BSDs have symlinked /dev/random to /dev/urandom for a long time already.
by simias 7y ago
As mentioned by the article that's already the default behaviour of getrandom() and the BSDs have symlinked /dev/random to /dev/urandom for a long time already.
I think this is a change for the best, in particular this bit sounds completely true to my ears:
> Theodore Y. Ts'o, who is the maintainer of the Linux random-number subsystem, appears to have changed his mind along the way about the need for a blocking pool. He said that removing that pool would effectively get rid of the idea that Linux has a true random-number generator (TRNG), which "is not insane; this is what the *BSD's have always done". He, too, is concerned that providing a TRNG mechanism will just serve as an attractant for application developers. He also thinks that it is not really possible to guarantee a TRNG in the kernel, given all of the different types of hardware supported by Linux. Even making the facility only available to root will not solve the problem: Application programmers would give instructions requiring that their application be installed as root to be more secure, "because that way you can get access the _really_ good random numbers".
The number of time I've had to deal with security-related software and scripts who insisted in sampling /dev/random and stalling for minutes at a time...
- JdeBP 7y agoA minor note: * Only FreeBSD symbolically links, and it does it in the other direction. urandom is the symbolic link to random. * OpenBSD has four distinct character device files: random, arandom, srandom, and urandom. * NetBSD (as of 2019) has two distinct character device files: random and urandom. They have different semantics from each other. https://netbsd.gw.com/cgi-bin/man-cgi?rnd+4+NetBSD-current https://netbsd.gw.com/cgi-bin/man-cgi?rnd+4+NetBSD-current
- aquabeagle 7y agoOn OpenBSD: $ ls -l /dev/*random* lrwxr-xr-x 1 root wheel 7 Dec 10 15:05 /dev/random@ -> urandom crw-r--r-- 1 root wheel 45, 0 Jan 6 15:30 /dev/urandom
- JdeBP 7y agoThat must be a recent change. $ ls -F /dev/*random* /dev/arandom /dev/random /dev/srandom /dev/urandom $
- ben_bai 7y agoDeleted in 2017. https://marc.info/?l=openbsd-cvs&m=151069089605712&w=2 https://marc.info/?l=openbsd-cvs&m=151069089605712&w=2 you can delete arandom and srandom Edit: better link
- guenthert 7y agoAnd you don't think they did so for a reason? If you don't care for security (and there are good reason why one wouldn't), then you can create the link yourself on those systems (or link to /dev/zero for extra low wait times). Why does now everyone have to suffer the same? What happened to "keep policy out of the kernel"?