Subject: Re: [Dtls-iot] Certificate Profiling

From: Hannes Tschofenig <[email-masked]>
Date: Wed, 27 May 2015 17:55:06 +0200

Hi Derek,

I added text to take your comment into account. Here is the new text:

"
   TLS/DTLS offers a lot of freedom for the use with ECC.  This document
   restricts the use of ECC ciphersuites to named curves defined in RFC
   4492 [RFC4492].  At the time of writing the recommended curve is
   secp256r1 and the use of uncompressed points to follow the
   recommendation in CoAP.  Note that standardization for Curve25519
   (for ECDHE) is ongoing (see [I-D.irtf-cfrg-curves]) and support for
   this curve will likely be required in the future.  To offer elliptic-
   curve signatures using the Edwards-curve Digital Signature Algorithm
   (EdDSA) standardization work on Ed25519 is also ongoing (see
   [I-D.josefsson-eddsa-ed25519]).
"

Ciao
Hannes

On 04/01/2015 10:17 PM, Derek Atkins wrote:
> Hannes Tschofenig <[email-masked]> writes:
> 
>> Hi all,
>>
>> Section 6.3 of draft-ietf-dice-profile-10 discusses the recommendations
>> for use with certificates.
>> While the current text restricts the use of certificates quite a bit I
>> got feedback that the current text still leaves several aspects untouched.
>>
>> Here is a proposal of further recommendations:
>>
>> * TLS/DTLS offers a lot of freedom for using ECC curves. I would suggest
>> to restrict the use of RFC4492-defined ECC ciphersuites to named curves
>> only.
> 
> Do we want to consider alternate key agreement schemes that may enable
> lower-powered devices to have lower overhead?
> 
> -derek
>

---

From: Derek Atkins <[email-masked]>
Date: Thu, 28 May 2015 12:16:35 -0400

Thanks, Hannes.

I was also trying to keep an open mind about, for example, Algebraic
Eraser (AEDH) for key agreement.  It's significantly faster and less
power-hungry than ECC so might be interesting for IoT applications where
speed and power consumption are important considerations.

-derek

Hannes Tschofenig <[email-masked]> writes:

> _______________________________________________
> dtls-iot mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/dtls-iot

-- 
       Derek Atkins                 617-623-3745
       [email-masked]             www.ihtfp.com
       Computer and Internet Security Consultant

---

From: Hannes Tschofenig <[email-masked]>
Date: Fri, 29 May 2015 23:20:13 +0200

Hi Derek,

I got it.

With the way the document is currently written it is not prohibited to
use other cryptographic algorithms with TLS. However, the
mandatory-to-implement algorithms are currently focusing on other
algorithms, which depend a bit on the type of credential being used.

We have taken a somewhat conservative approach in the selection since we
re-use the algorithm from previously published specifications. So far,
nobody had complained about that approach.

Ciao
Hannes