Re: [TLS] Adoption call for TLS Flag - Request mTLS

[Mohit Sethi <[e-mail]>]

Please see my earlier comment regarding this draft: 
https://mailarchive.ietf.org/arch/msg/tls/g3tImSVXO8AEmPH1UlwRB1c1TLs/

In summary: the functionality of this draft is already achievable by 
using the client_certificate_type extension defined in RFC 7250: 
https://datatracker.ietf.org/doc/html/rfc7250 with certificate type 
value = 0: 
https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#tls-extensiontype-values-3.

The table in section 4.2 of RFC8446 even mentions that the extension can 
be included in the ClientHello: 
https://datatracker.ietf.org/doc/html/rfc8446#section-4.2, thereby 
ensuring that the server sends a CertificateRequest message in response 
to the ClientHello received.

OpenSSL already implements this extension since it was needed for 
support raw public keys (RPKs).

As stated earlier: if it is indeed the case that the 
client_certificate_type extension is suitable for the use-case, then 
perhaps it is preferable to not have a separate flag. Otherwise, it 
would make the state machine at the server more complicated (for 
example: handling a ClientHello with both the mTLS flag and the 
client_certificate_type extension.

Therefore, like Ekr, I am mildly negative on adopting this document but 
for different reasons.

--Mohit

On 4/3/24 00:52, Sean Turner wrote:
> At the IETF 119 TLS session there was some interest in the mTLS Flag I-D (https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-jhoyla-req-mtls-flag%2F&data=05%7C02%7Cmohit.sethi%40aalto.fi%7C42877de6d3d64135e49e08dc534a463b%7Cae1a772440414462a6dc538cb199707e%7C1%7C0%7C638476825681199391%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=ERzWFcuBlAfobNyGCcgKDhCl9wex9LOQ%2F3yPYC7idfU%3D&reserved=0); also, see previous list discussions at [0]. This message is to judge consensus on whether there is sufficient support to adopt this I-D.  If you support adoption and are willing to review and contribute text, please send a message to the list.  If you do not support adoption of this I-D, please send a message to the list and indicate why.  This call will close on 16 April 2024.
>
> Thanks,
> Deirdre, Joe, and Sean
>
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