Re: [Keyrings] Re: [PATCH 01/04] Add multi-precision-integer maths library

[David Härdeman <david@2gen.com>]

On Sat, Jan 28, 2006 at 10:20:29PM -0500, Trond Myklebust wrote:
> On Sat, 2006-01-28 at 17:57 +0100, David Härdeman wrote:
> > What about the first paragraph of what I wrote? You are going to want to 
> > keep often-used keys around somehow, proxy certificates is not a 
> > solution for your own use of your personal keys and with the exception 
> > of hardware solutions such as smart cards, the keys will be safer in the 
> > kernel than in a user-space daemon...
>
> I don't get this explanation at all.
>
> Why would you want to use proxy certificates for you own use? Use your
> own certificate for your own processes, and issue one or more proxy
> certificates to any daemon that you want to authorise to do some limited
> task.

I meant that you can't use proxy certs for your own use, so you still need 
to store your own cert/key somehow...and I still believe that the kernel 
keyring is the best place...

> ...and what does this statement about "keys being safer in the kernel"
> mean?

swap-out to disk, ptrace, coredump all become non-issues. And in 
combination with some other security features (such as disallowing 
modules, read/write of /dev/mem + /dev/kmem, limited permissions via
SELinux, etc), it becomes pretty hard for the attacker to get your 
private key even if he/she manages to get access to the root account.

> > Further, the mpi and dsa code can also be used for supporting signed 
> > modules and binaries...the "store dsa-keys in kernel" part adds 376 
> > lines of code (counted with wc so comments and includes etc are also 
> > counted)...
>
> Signed modules sounds like a better motivation, but is a full dsa
> implementation in the kernel really necessary to achieve this?

How would you do it otherwise?

Re,
David
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