Re: [OAUTH-WG] draft-ietf-oauth-mtls-03: jwk / x5c sanity checks when registering for pub_key_tls_client_auth

Brian Campbell <> Tue, 29 August 2017 15:14 UTC

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From: Brian Campbell <>
Date: Tue, 29 Aug 2017 09:14:05 -0600
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To: Vladimir Dzhuvinov <>
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Subject: Re: [OAUTH-WG] draft-ietf-oauth-mtls-03: jwk / x5c sanity checks when registering for pub_key_tls_client_auth
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Sec 4.7 of RFC 7517 <>,
which defines "x5c" for JWK, says that the "key in the first certificate
MUST match the public key represented by other members of the JWK." Thus,
how I read it anyway, the check you mention is already a requirement of the
JWK layer.

On Tue, Aug 29, 2017 at 1:28 AM, Vladimir Dzhuvinov <
> wrote:

> Aspects of this were previously discussed, on and off list.
> According to section 2.3, clients registering for public key bound mTLS
> auth must register their public keys as JWKs, or client X.509
> certificate (as x5c parameter in RSA and EC JWK).
> In the latter case, are there any security implications if there is
> mismatch between the registered x5c and the top-level public key JWK
> parameters? Should the AS perform some sanity checks on the JWK parameters?
> A client could for instance register a JWK where the top-level JWK
> public key doesn't match the public key in the x5c (as key type, or
> public key value).
> Thanks,
> Vladimir
> _______________________________________________
> OAuth mailing list

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