Hi Panos,
I wonder what kind of devices you have in mind? On one hand, the devices
are constrained enough not to have resources for generating
cryptographic quality randomness. But they somehow have support for
tamper-resistance identity protection? Is it cheaper to have
tamper-resistance? And is it somehow more energy-efficient?
I understand that generating strong identities and storing them securely
are different issues. But I would be interested to learn about IoT
devices that have tamper-resistance storage but no possibility of
generating cryptographic quality randomness. Also, what protocols do you
think the devices would use for authenticating these identities?
--Mohit
On 05/15/2018 05:00 PM, Panos Kampanakis (pkampana) wrote:
Hi Mohit,
These priv/public keypairs+cert are provisioned and used on the
endpoint as identity for authentication. If tamper-resistance is not
supported on the endpoint, the keypairs could be reprovisioned more
often than the traditional cert lifetime as the server-side key gen
transaction does not incur significant workload to the endpoint itself.
Rgs,
Panos
*From:*Mohit Sethi [mailto:[email protected]]
*Sent:* Tuesday, May 15, 2018 1:37 AM
*To:* Panos Kampanakis (pkampana) <[email protected]>; Hannes
Tschofenig <[email protected]>; [email protected]
*Subject:* Re: [Ace] EST over CoAP
Hi Panos,
How do you intend to use these server generated keys once they are
provisioned onto the device?
--Mohit
On 05/14/2018 04:58 PM, Panos Kampanakis (pkampana) wrote:
Hi Hannes,
To address your question about server-side key gen, below is the
explanation we have put in the draft already and will be in the
next iteration
/~~~~~~~~~~~~~/
/ Constrained devices sometimes do not have the necessary
hardware to/
/ generate statistically random numbers for private keys and DTLS/
/ ephemeral keys. Past experience has shown that cheap endpoints/
/ sometimes generate numbers which could allow someone to
decrypt the/
/ communication or guess the private key and impersonate as the
device./
/ Studies have shown that the same keys are generated by the
same model/
/ devices deployed on-line./
//
/ Additionally, random number key generation is costly, thus energy/
/ draining. Even though the random numbers that constitute the/
/ identity/cert do not get generated often, an endpoint may not
want to/
/ spend time and energy generating keypairs, and just ask for
one from/
/ the server./
//
/ In these scenarios, server-side key generation can be used. The/
/ client asks for the server or proxy to generate the private
key and/
/ the certificate which is transferred back to the client in the/
/ server-side key generation response./
/~~~~~~~~~~~~~/
This is a need that we have heard from customers at Cisco.
About the proxy-Registrar question, we already have made the
change in the working copy of the draft as well. We no longer call
this functionality proxying, but instead use the concept of the
registrar that terminates the connection and establishes the next
one.
We didn’t add any new features in the doc after removing the BRSKI
stuff.
If you want an early preview to comment on, we can share the
repository with you.
Panos
*From:* Ace [mailto:[email protected]] *On Behalf Of *Hannes
Tschofenig
*Sent:* Monday, May 14, 2018 5:05 AM
*To:* [email protected] <mailto:[email protected]>
*Subject:* [Ace] EST over CoAP
Hi all,
At IETF#101 Peter presented a list of open issues with the EST
over CoAP draft, see
https://datatracker.ietf.org/meeting/101/materials/slides-101-ace-est-over-secure-coap-00
-Operational parameter values
-Server side key generation using simple multipart encoding
-Explain trust relations for http/coap proxying
I have challenged the usefulness of the server-side key generation
during the meeting but in general I am curious where we are with
the document. It would be great to get it finalized. It appears
that we are adding new features and therefore will not be able to
complete the work in any reasonable timeframe.
So, do we have a plan for how to complete the document?
Ciao
Hannes
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