[cryptography] Kernel space vs userspace RNG

shawn wilson ag4ve.us at gmail.com
Thu May 5 05:40:51 EDT 2016

Just reflecting on the Linux RNG thread a bit ago, is there any technical
reason to have RNG in kernel space? There are things like haveged which
seem to work really well and putting or charging code in any kernel can be
a bit of a battle (as it should be with code as complex as that involving
crypto - wouldn't want people missing an exploit your new system exposes
and accepting it*). So I wonder what the gain is for putting RNGs in the

The only argument I can think of against this is non technical - if you
rely on users to pick their RNG implementation, they are liable to get it
wrong. This may be valid but I'm still curious about the technical reasons
for RNG in kernel space.

Also, if kernel space is really necessary, I'd think publishing as a dkms
type package would gain more traction for getting into mainline (but this
is probably OT here)

* Obviously that same argument can be made of userspace programs but I'd
much prefer my exploits happen at a less privileged ring whenever possible
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