Re: [Emu] Idea: New X509 Extension for securing EAP-TLS

[Russ Housley <[e-mail]>]

> On Nov 12, 2019, at 2:53 AM, Jan-Frederik Rieckers <[e-mail]> wrote:
> 
> Signed PGP part
> On 12.11.19 00:15, Owen Friel (ofriel) wrote:
>> One deployment consideration is if an operator wants to use a public PKI (e.g. Lets Encrypt) for their AAA certs, then it could be years, if ever, before these extensions could be supported (as Alan alludes to), so it would also be good to define how this could work with standard RFC 6125 DNS-IDs / RFC 5280 dNSNames.
> 
> I had a lot of thoughts about this topic.
> I am experimenting with certificates in EAP-TLS contexts and experienced
> the problems with getting a certificate with specific extension
> properties from our public PKI. (In my case a test certificate with a
> critical MustStaple extension)
> 
> The Problem with dNSNames is that they are also used in other contexts
> (mainly HTTPS). There would be the possibility to define a specific
> prefix to bind it to a Realm without having the certificate being valid
> for the HTTPS host (e.g. eap-tls.uni-bremen.de for the realm
> uni-bremen.de) but I don't see the advantage in that.
> This will probably don't really lead to a change in the supplicants
> implementations.
> 
> My deployment experience shows, that the certificate check is the main
> security problem in WPA2-Enterprise networks. I have seen instructions
> for installing WPA2-Enterprise networks where they have explicitly
> suggested switching off the certificate check, probably because it was
> too complicated for the users and would lead to people complaining at
> the IT department about the complicated setup.
> 
> A setup of WPA2-Enterprise can be secure if all devices are part of a
> centralized Device Management, but especially in eduroam this isn't
> possible. We have a lot of people who don't really care about security.

Can the extended key usage for EAP over a LAN ( id-kp-eapOverLAN ) solve this for you?  It is defined in RFC 4334.  A certificate for Web PKI should not include this extended key usage.

RFC 4334 also offers a certificate extension that lists the SSIDs that are associated with the server.

Russ