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Re: [core] Last Call: <draft-ietf-core-block-18.txt> (Block-wise transfers in CoAP) to Proposed Standard

Ludwig Seitz <ludwig@sics.se> Tue, 02 February 2016 10:24 UTC

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From: Ludwig Seitz <ludwig@sics.se>
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Date: Tue, 02 Feb 2016 11:24:14 +0100
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Subject: Re: [core] Last Call: <draft-ietf-core-block-18.txt> (Block-wise transfers in CoAP) to Proposed Standard
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On 01/29/2016 08:36 AM, Carsten Bormann wrote:
> Hi Jim,
>
> [...]  I think the biggest remaining question with this
> is what to do against an attacker polluting a cache with a bad block
> (creating a problem for availability, not integrity).  (In RFC7252's
> security model, DTLS prevents that from happening.)
>

I think that this is the point we were considering when we thought it 
would be good to protect individual fragments.

If you receive a fragment, you'd like to be able to verify that it is 
legit, before you store it, and before you request further fragments.

Otherwise it's just to easy to fill up the memory of a constrained 
device with junk.

/Ludwig



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Ludwig Seitz, PhD
SICS Swedish ICT AB
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