[ippm] Re: John Scudder's Discuss on draft-ietf-ippm-encrypted-pdmv2-09: (with DISCUSS and COMMENT)

[John Scudder <[e-mail]>]

Hi Nalini,

I was reviewing my DISCUSS positions and wanted to check in to make sure you’re not waiting on me for anything.

No rush, I just don’t want to be the long pole.

—John

On Nov 1, 2024, at 11:50 PM, [e-mail] wrote:


[External Email. Be cautious of content]


John,

> I’ve long since concluded that it’s usually impossible to know with certainty that one has considered every consequence of a
> design decision concerning how it might be abused. The literature on side-channel attacks makes interesting reading (though > it would have been more appropriate yesterday, on Halloween… some of that stuff is pretty scary).

True, indeed.   There may be unintended consequences that I lack the imagination to foresee.

> > Having said all this, we can certainly put some subset of the above as a guidance to the implementor in the draft to make it >> explicit that the value of the Global Counter can be seen by all users of the particular server.

> That’s all I’m looking for… although now that I’m writing it, I wonder if it would also be worth saying the global pointer MAY be > omitted if so configured, for the benefit of a user who isn’t comfortable with the expanded attack surface. (I suppose this would > be achieved by just sending it as constant zero or something.)
We will add some discussion of this topic as guidance to the implementor in the security / privacy considerations.  I need to think a bit about what goes where.   I think it is a good idea to allow MAY be omitted for the Global Pointer (should be calling this Global Packet Count!) but then it MUST be zeroes.

Thanks,

Nalini Elkins
CEO and Founder
Inside Products, Inc.
https://www.insidethestack.com<https://urldefense.com/v3/__http://www.insidethestack.com__;!!NEt6yMaO-gk!E8wff4bhTLuw7iFtJzb_8q2St21BmNJc6Z3XUEBL9T9nZztc76nPMmDT20DQJV72vf5zilqitUC92nFhYhImepFDguCx$>

President
Industry Network Technology Council
https://www.industrynetcouncil.org


On Friday, November 1, 2024 at 06:31:58 PM GMT+1, John Scudder <[e-mail]> wrote:


Hi Nalini,

Thanks for your careful reply.

> On Oct 27, 2024, at 3:22 AM, [e-mail]<mailto:[e-mail]> wrote:
>
> My thought on one client being able to see the aggregate number of packets sent by the server to all clients when using a server which serves multiple organizations is that, yes, this is an exposure but how one would use this in a way that is detrimental eludes me.

Me, too, and thanks for your effort at thinking through some of the attack surface (which I’ve elided).

I’ve long since concluded that it’s usually impossible to know with certainty that one has considered every consequence of a design decision concerning how it might be abused. The literature on side-channel attacks makes interesting reading (though it would have been more appropriate yesterday, on Halloween… some of that stuff is pretty scary).

> Having said all this, we can certainly put some subset of the above as a guidance to the implementor in the draft to make it explicit that the value of the Global Counter can be seen by all users of the particular server.

That’s all I’m looking for… although now that I’m writing it, I wonder if it would also be worth saying the global pointer MAY be omitted if so configured, for the benefit of a user who isn’t comfortable with the expanded attack surface. (I suppose this would be achieved by just sending it as constant zero or something.)


Thanks,

—John