Re: [Ace] [Secdispatch] EDHOC

Richard Barnes <> Fri, 18 January 2019 16:55 UTC

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From: Richard Barnes <>
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Date: Fri, 18 Jan 2019 11:54:58 -0500
Cc: Kathleen Moriarty <>, "" <>, Francesca Palombini <>, John Mattsson <>, "" <>
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Subject: Re: [Ace] [Secdispatch] EDHOC
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Let me provide some additional context.  When the chairs and ADs discussed this in BKK, it seemed pretty clear that EDHOC is not within the current charter of ACE — after all, ACE is targeted at authentication and authorization, not key exchange.  Since ACE would need to recharter to accept this work in any case, and because EDHOC overlapped with the interests of other working groups, it seemed to make sense to have the conversation in a broader venue.

Göran: Your email starting this thread seems like an abbreviated summary of the past discussion of this draft.  Since this is a new audience, it would be helpful if you could start from the underlying requirements (“we need an AKE with certain constraints”) and lay out why new protocol work is needed, vs. profiling existing protocols (as has been done, e.g., in DICE).

If it would be helpful to keep this moving, we could certainly arrange a virtual interim on this topic.


> On Jan 4, 2019, at 1:17 AM, Göran Selander <> wrote:
> Hi Kathleen,
> Good question. Thanks for bringing continuity to this almost 2 years long offline discussion. Indeed, lack of comparison with other protocols and formal verification were at the time the arguments for not following up the in-room consensus with an email confirmation. And, as you noted, that is not the case anymore.
> Meanwhile the ACE chairs and AD have changed. My understanding is that the argument now is about attracting more people with a certain security competence for which perhaps another WG could potentially be better, hence the request to Secdispatch. But I'll pass the question on and include the ACE WG for transparency.
> From the authors' humble point of view we believe that the main missing thing that would enable the required further discussion is that the IETF endorses this work, no matter how, so that people dare invest more time in implementation and analysis. 
> Best regards,
> Göran
> On 2019-01-03, 00:58, "Kathleen Moriarty" <> wrote:
>    Hi,
>    I’ve read earlier versions of this draft and appreciate all the work you have done with the security proof and comparing to existing standardized protocols.  If ACE is interested, why is this going to SECDispatch? It might help to understand that better.  Is it that a recharter would be needed?
>    Thank you & happy new year!
>    Kathleen 
>    Sent from my mobile device
>> On Jan 2, 2019, at 5:56 PM, Göran Selander <> wrote:
>> Dear Secdispatch,
>> We have been advised to ask secdispatch to consider EDHOC:
>> Those that follow the ACE WG should be familiar with this draft. The problem statement and motivation for EDHOC is described in section 1. In brief, the target is a lightweight key exchange protocol suitable for IoT applications, which:
>> a) has small message size and reuses existing IoT primitives to enable low overhead and small code footprint; 
>> b) is not bound to a particular transport, to enable end-to-end security in IoT deployments with varying underlying layers; and
>> c) can be used to key OSCORE (draft-ietf-core-object-security) that is lacking a harmonizing key exchange protocol.
>> These requirements are motivated by constrained IoT device deployments, but the protocol is applicable to other end-to-end security settings where the overhead due to security needs to be low. EDHOC addresses these requirements and builds on the SIGMA construction for Diffie-Hellman key exchanges. EDHOC, like OSCORE, is built on CBOR (RFC 7049) and COSE (RFC 8152) and the protocol messages may be transported with CoAP (RFC 7252).  
>> There has been a number of reviews of different versions of the draft; both by people who want to deploy it and by people analysing the security. A formal verification was presented at SSR 2018. There are a few implementations of different versions of the draft. The ACE WG has expressed interest in this work in several f2f meetings.
>> Please let us know if some information is missing for secdispatch to consider this draft, or how we can help out in the process.
>> Best regards
>> Göran, John, Francesca
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