cvs commit: src/sys/libkern arc4random.c

Sam Leffler sam at
Fri Aug 15 12:17:49 PDT 2003

> In message <87953260.1060949270 at>, Sam Leffler writes:
>> Note that the data generated by arc4random needs to be exported to user
>> apps for seeding crypto operations when operating in a chroot'd
>> environment  where /dev/random is not available.
> I actually thought about that a bit, and I think "/dev/random" is
> a wrong concept.
> I think we should have a randomdata(2) system call instead.
> Having a /dev/random which is sometimes (chroot/jail) means that
> applications running under those circumstances are incredible fragile
> to spoofing by creating a fake "/dev/random" in some way.

openbsd defined a sysctl to get data from arc4random.  They use this as a 
fallback if /dev/random or similar is not available.  Applications that 
wanted to be paranoid about spoofing could use this directly.  I have not 
compared the goodness of the data from /dev/random and arc4random.


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