[Servercert-wg] [External Sender] Discussion about single-purpose client authentication leaf certificates issued from a server TLS Issuing CA

[Clint Wilson]

Hi Pedro,

All CAs in the Apple Root Program are required to complete an audit based on either WebTrust Principles and Criteria for Certification Authorities or ETSI EN 319 411-1 LCP, NCP, or NCP+ per Section 1.1.1 of the ARP Policy. For clientAuth-only CAs, these are currently the only audit criteria.

I appreciate the comment regarding TLS CAs; I’ll look at improving this language, but this specifically is referencing CAs capable of asserting the serverAuth EKU as clientAuth is not required for TLS. That is, the serverAuth EKU is required at a protocol level to establish a secure TLS connection, while the clientAuth EKU is only used in specific contexts, such as mTLS — which is almost always a use-case better (or perhaps more ideally) solved by Enterprise or Private PKIs.

Thanks!
-Clint

> On May 17, 2024, at 2:32 AM, Pedro FUENTES <pfuentes at wisekey.com> wrote:
> 
> I also oversaw that…
> 
> Anyhow… @Clint, what are the audit requirements for these clientAuth CAs?
> In your program you mention WTBR as a requirement for "TLS CAs”, but there’s no distinction between clientAuth or serverAuth… while both are used to secure TLS handshakes.
> 
>> On 17 May 2024, at 11:22, Dimitris Zacharopoulos (HARICA) <dzacharo at harica.gr> wrote:
>> 
>> 
>> 
>> On 16/5/2024 10:29 μ.μ., Clint Wilson wrote:
>>>> AFAIK Apple and Mozilla also don't have a specific "trust bit" for Client Authentication. Only Microsoft does.
>>> FWIW, Apple does indeed have a specific trust bit for id-kp-clientAuth EKU and allows for (and ships) dedicated clientAuth Root CAs in the Apple Root Program (as outlined in 2.1.3 of the ARP Policy).
>>> 
>> 
>> Thanks for the correction Clint. I had the impression that you shipped only Apple Roots for clientAuth. My bad.
>> 
>> Dimitris.
>> 
>> 
>> 
> 
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