[Ndn-interest] NACKs in ICN

Marc.Mosko at parc.com Marc.Mosko at parc.com
Tue Mar 10 09:09:57 PDT 2015

I’ll second Mark’s opinion that it’s great to get a lot of these issues with cnacks and fnacks written up and public.  

I agree that cnaks pose potential computational DoS attacks and when cached content DoS.  As to a solution to safely use cnacks, I think it will depend a lot on how the interests are being used.  For example, using Interests for content discovery where you issue a long-standing interest waiting for the next item would probably use a different cnack approach than someone trying to do something else.  

I think in the case of fnacks, having a secure neighbor protocol and local key exchange in ccnx/ndn would go a long way towards making fnacks practical.  This seems like a much lower barrier than cnacks.

In section IV.E (experimenting with cnacks), did this include an signing time too or was it from cache pollution?  It wasn’t clear what specifically contributed to the increased time.

Also, if a producer will issue a cnack for plausible content and not random names, isn’t that a big information leak for someone name scanning?  That’s like a firewall sending an ICMP packets to let a hacker know when they’re on the right track (well, I guess its the opposite, as a bad firewall sending prohibited is for bad ports and a cnack for a plausible name is for a good name).


On Mar 10, 2015, at 7:15 AM, Mark Stapp <mjs at cisco.com> wrote:

> Thanks for sending this around, Cesar. It's certainly good to see some details confirming the intuition that it would be costly for producers to try to use public-key operations on adversary-selected inputs as a means of denial-of-existence. but ... the paper doesn't explore many alternative schemes - we presented five, I think, at the last icnrg meeting. the conclusion of the paper - that NACKs have security problems - seems a little strong, based on the small number of approaches considered.
> It would be very interesting to see whether your analytical tools might be able to be applied to some of the other approaches.
> Thanks,
> Mark
> On 3/9/15 9:14 PM, Cesar Ghali wrote:
>> Hi all,
>> Some of you might be interested in the following report:
>> A. Compagno, M. Conti, C. Ghali, G. Tsudik,
>> To NACK or not to NACK? Negative Acknowledgments in Information-Centric
>> Networking,
>> arXiv: 1503.02123, March 7, 2015.
>> URL: http://arxiv.org/pdf/1503.02123v1.pdf
>> Of course, comments are appreciated.
>> Thanks,
>> Cesar
>> --
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