Messages in this thread | | | Date | Mon, 6 Oct 2008 21:26:41 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH] ELF: implement AT_RANDOM for future glibc use |
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> We're already using get_random* for stack, heap, and brk. Also, > get_random* uses the nonblocking pool, so this is the same as if userspace > had tried to pull bytes out of /dev/urandom, which (as I understand it)
Yes exactly that's the problem. Think about it: do you really need the same cryptographic strength for your mmap placement as you need for your SSL session keys?
And if you need true entropy for your session keys do you still get it when it was all used for low security purposes first?
> > What you should instead do is to initialize some other cryptographic RNG > > regularly and use the output of that. > > Can you give me some examples of this? I thought the nonblocking > entropy pool was specifically for this purpose?
It's definitely not a "general purpose random number generator" or even a "general purpose secure random number generator"
Since so many systems have poor entropy input /dev/urandom has generally replaced /dev/random for near all cryptographic software, so it's just the new black.
-Andi
-- ak@linux.intel.com
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