[lamps] Re: TLS Client Certificates; a survey

[John Mattsson <[e-mail]>]

Hi Eric,

Thanks for the clarification. I wanted to state that endpoint typically do not do revocation checking. Correct me if I am wrong, but my understanding is that browsers the revocation checking in browsers is often only partial and with soft-fail. And I don’t consider soft-fail revocation checking to be revocation checking at all.

(I really don’t want to imply that WebPKI and browsers are doing a bad job. I think they are doing a great job for the Web use case. It is just not very suitable for other sectors such as enterprise, government, telecom, etc.)

Cheers,
John Preuß Mattson

From: Eric Rescorla <[e-mail]>
Date: Monday, 23 March 2026 at 16:02
To: John Mattsson <[e-mail]>
Cc: Salz, Rich <[e-mail]>, Tls <[e-mail]>, [e-mail] <[e-mail]>
Subject: Re: [lamps] Re: TLS Client Certificates; a survey



On Mon, Mar 23, 2026 at 7:46 AM John Mattsson <john.mattsson=[e-mail]<mailto:[e-mail]>> wrote:
Very unrelated from WebPKI, but almost all 3GPP use of TLS, DTLS, and QUIC are mutually authenticated and will continue rely on TLS-Client certificates. 3GPP relies on the Internet PKI profile (RFC 5280) for everything including device certificates. I think the same applies to the other large use cases of mTLS in enterprise, government, and IoT.

I am worried about recent trends to use WebPKI for non-Web use cases. The WebPKI relies on hundreds of trusted roots, have quite weak security for issuance, does not do revocations,

This statement is not correct. The WebPKI does do revocations. In fact, there are so many
revocations (about 8 million/1% of the issued number) that you need special data structures
to efficiently propagate the revocations to the browser [0]

-Ekr

[0] https://research.mozilla.org/files/2025/04/clubcards_for_the_webpki.pdf?_gl=1*11knujb*_ga*MTM3MDA3NjU1My4xNzYyMzgyNzQ1*_ga_X4N05QV93S*czE3NzQyNzc5OTMkbzI5JGcwJHQxNzc0Mjc3OTkzJGo2MCRsMCRoMA..

and now will not do client authentication. It is very unsuitable for most other use cases. Similarly, technologies and policies like transparency and short-term certificates might not be adding much for other applications.

Cheers,
John Preuß Mattsson

From: Salz, Rich <rsalz=[e-mail]<mailto:[e-mail]>>
Date: Monday, 23 March 2026 at 15:36
To: Tls <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>
Subject: [TLS] TLS Client Certificates; a survey

Since WebPKI CA’s will not be able to issue TLS-Client certificates, what are the customers and CAs thinking of doing?

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