Re: [Danish] Charter Text and the Problem Statement

[Ash Wilson <[e-mail]>]

Hi Hannes,
Great questions, responses in-line below...

On Wed, Jun 16, 2021 at 11:43 PM Hannes Tschofenig <
[e-mail]> wrote:

> Thanks for your feedback, Ash.
>
>
>
> It is interesting that you mention the network access authentication use
> case. Do you envision EAP-TLS in combination with Danish to work
> architecturally differently than the current EAP-TLS-based approach?
>

We hope to minimize the amount of work required to enable DANE client ID
for EAP-TLS. Some challenges remain with EAP-TLS in conjunction with TLS
1.3: https://datatracker.ietf.org/doc/html/draft-ietf-emu-eap-tls13-16.
Supporting TLS 1.2 for EAP-TLS and DANE would likely be more
straightforward, but I do not know whether there's much interest in
updating TLS 1.2 to cover this use case.

DANE server authentication with EAP-TLS brings another challenge: the
absence of IP connectivity prior to authentication. This could be remedied
by
https://datatracker.ietf.org/doc/html/draft-ietf-tls-dnssec-chain-extension-07,
if the work on that draft were to continue. There are also challenges with
validating the chain, tied to root key rotation. Devices which remain
unplugged too long may not be able to authenticate. On the other hand, it
is a best practice to ensure that a device is patched before putting it
into production, and updating roots of trust fits within the scope of that
sort of activity.

If only DANE for client authentication is supported in EAP-TLS, which is
the likely initial outcome, the challenge of getting the authentication
server's CA certificate onto the device still exists. This still represents
a reduction in effort on the part of the IT staff, but not a perfect
zero-touch onboarding unless the supplier also provisions the CA certs for
the authentication server... and in the case of WiFi, the SSID to associate
with. Still, we think this represents a substantial improvement in the
onboarding experience for the implementer.


>
> You write:
>
> “Credential issuance very often requires the device and the person
> bootstrapping the identity to be in the same place”
>
>
>
> Binding the user to his or her device typically takes some time. It often
> requires the user to log into some service and to “add” the new device
> often by demonstrating physical possession. Of course, this is the way how
> it works for end consumer products, where scalability is less of an issue
> because you are probably not going to buy thousands of smart coffee
> machines. For a commercial setup, the process often works different but it
> very much depends on the type of industry vertical you are in. There is
> often a non-irrelevant configuration step involved as well. For example,
> with commercial indoor lighting professionals need to configure different
> lighting themes.
>
>
>
> I don’t see any of this user-related interaction being covered as part of
> the chartered work.
>

DANE can be useful for home IoT. I think that it could reduce the
complexity of automation wherever private PKI is being managed in the
consumer's environment, and accelerate and simplify the onboarding
experience. IETF is accessible and wide-reaching, and seems like the right
place to present and refine the design pattern that might be adopted later
by other standards (like CHIP/Matter). I'm also operating under the
assumption that enterprise IoT has a more recognized need for
interoperability and simpler secure onboarding processes. That is a big
assumption, and only based on my observations thus far. I'm open to
including the home consumer's perspective in this effort, if you think it's
worthwhile.

As far as describing the general onboarding experience for the implementer,
I had hoped to include that in the architecture document along with
examples of how DANE might interface with and support other standards in
the broader ecosystem. In trying to keep the charter concise, I think we
left out some important information.

You bring up an interesting point, with the configuration of lighting
profiles during fixture installation. The expectation is that with DANE as
the authentication protocol, the variety of suppliers producing devices for
a given application might be able to agree on a format for representing
configuration information, and devices can securely retrieve it from the
system that manages the application's configuration. I think that it would
be especially useful to show how DANE works with other discovery protocols
(mDNS, for instance) in the process of retrieving the device's
configuration. Where do you think this fits best? In the architecture
document, or would another format be a better fit for this?


>
> Ciao
>
> Hannes
>
>
>
> *From:* Ash Wilson <[e-mail]>
> *Sent:* Wednesday, June 16, 2021 11:28 PM
> *To:* Hannes Tschofenig <[e-mail]>
> *Cc:* [e-mail]
> *Subject:* Re: [Danish] Charter Text and the Problem Statement
>
>
>
> Hi Hannes,
>
> Thanks for the questions, and apologies for keeping you waiting on
> answers/clarification.
>
>
>
> On Wed, Jun 16, 2021 at 4:12 AM Hannes Tschofenig <
> [e-mail]> wrote:
>
> Hi all,
>
>
>
> I have been reading through the charter text in an attempt to understand
> the problem statement.
>
>
>
> Two problems are mentioned:
>
>
>
> 1)  Challenges with naming collisions in the IoT space.
>
>
>
> 2)  Credential issuance is time consuming.
>
>
>
> Ad 1: Reading through the text it feels like naming collisions are a big thing in IoT. I have not heard about those problems. Could you elaborate?
>
> Certainly. I'll use a hospital as an example environment.
>
>
>
> Within a hospital, it is desirable to implement 802.1x authentication
> using EAP-TLS for access to protected networks. EAP-TLS enables the use of
> PKI-based identity to authenticate an entity for network access.
>
>
>
> When implementing EAP-TLS for network access, RADIUS is a common
> protocol/server used for authentication behind the switch or wireless
> access point. Guidance for configuring RADIUS recommends the use of only
> one CA certificate for authenticating supplicant certificates. This
> guidance can be found in the wild in Freeradius configuration files for
> EAP-TLS, related to the 'ca_file' configuration directive.
>
>
>
> CAs guarantee the uniqueness of an entity's name within the scope of the
> CA, but have no method for enforcing name uniqueness across other CAs. For
> instance, CA1 and CA2 may both sign certificates for entities with the same
> name. If CA1 and CA2 are both trusted by the RADIUS server, and two
> entities named "medicaldevice123" exist, one per CA, then the resulting
> ambiguity makes it difficult to appropriately apply access controls. This
> ambiguity is mitigated by operating a single organizational PKI, and
> requiring identities issued by that single organizational PKI for EAP-TLS
> authentication.
>
>
>
> Onboarding devices to organizational PKI requires time and effort.
> Oftentimes some sort of skilled labor and/or dedicated infrastructure for
> automating the onboarding process is involved. DANE allows us to bind a DNS
> name to a public key, and mitigates the ambiguities introduced by the use
> of multiple CAs. An organization can only issue working identities within
> its own namespace in DNS. Since naming ambiguity can be mitigated using
> DANE, we may now choose to use manufacturer-issued PKI, represented in DNS,
> for authenticating entities.
>
>
>
> From the hospital's standpoint, the IT staff no longer needs to manage the
> process of onboarding devices to organizational PKI. The device arrives
> on-site with an identity which can be immediately used for
> network authentication.
>
> You add that “In response to the challenges related to
>
> ambiguity between identities issued by different CAs, application owners
>
> frequently choose to onboard IoT devices to a single CA.”. Is that a good or a bad development?
>
> It is a good development if the organization really wants to directly
> manage all of the credentials for all of the application participants. The
> effort and rationale behind BRSKI (RFC 8995) suggests a desire to make
> onboarding to organizational PKI easier to automate.
>
>
>
> If a supplier issues a trustworthy identity for a device, and DNS prevents
> another PKI from issuing working credentials under the same name, then
> issuing another identity via organizational PKI becomes superfluous. This
> is where we think that time and effort can be saved, because the skills
> required for onboarding do not need to include the management and issuance
> of identities under organizational PKI.
>
>
>
> Ad 2: Is it really true that credential issuance is time consuming? Why is
> that? For whom is it time consuming?
>
> Credential issuance very often requires the device and the person
> bootstrapping the identity to be in the same place. Some platforms and
> protocols exist to make that process easier (like BRSKI) or less
> human-involving. The time investment seems to be on the part of both the
> manufacturer (in issuing the IDevID) as well as the organizational IT
> staff, who manage the organizational PKI.
>
>
>
> Ciao
>
> Hannes
>
>
>
> PS: You use the term “Certificate Authority (CA)”. It is actually called
> “Certification Authority”.
>
>
>
>
>
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>
>
> --
>
> *Ash Wilson* | Technical Director
>
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*Ash Wilson* | Technical Director
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