Re: [OAUTH-WG] security considerations for draft-ietf-oauth-mtls-12

[John-Mark Gurney <[e-mail]>]

I do not have a good enough understanding of OAuth nor how it is used
in this draft to be able to write a proper security considerations
section about it.  You mention that the OAuth certification is
different than one for client cert authentication, but as I don't know
the standard well enough, I do not know the implications of it.

Even if the paragraph reads something like: Though client certs are
public in TLS versions 1.2 and before, they are not a privacy concern
because of x, y and z.  This would allow people who are reviewing it
to understand why it is not a privacy issue.

I only briefly reviewed this document because a coworker asked about
it, but I raised this concern because it was not mentioned in the
security considerations section.
On Thu, Nov 1, 2018 at 7:37 AM Brian Campbell
<[e-mail]> wrote:
>
> To be honest, I thought that was a relatively well known aspect of TLS 1.2 (and prior) and a noted difference of the new features in TLS 1.3. Also, I'd note that we're well past WGCL for this document. But, with that said, I suppose adding some privacy considerations text on the subject is worthwhile. Would you propose some text for the WG to consider, John-Mark? Bearing in mind that the implications of a certificate presented by, and representing, an OAuth client are somewhat different than for an end-user doing client cert authentication.
>
>
>
>
> On Wed, Oct 31, 2018 at 4:12 PM John-Mark Gurney <[e-mail]> wrote:
>>
>> I would suggest that the security considerations section of
>> draft-ietf-oauth-mtls-12 be expanded to include the privacy
>> implications of using this on versions of TLS before 1.3.  On all
>> versions of TLS before 1.3, the client cert is not encrypted and can
>> be used by third parties to monitor and track users.  I recently
>> posted a blog entry about this:
>> https://blog.funkthat.com/2018/10/tls-client-authentication-leaks-user.html
>>
>> Thanks.
>>
>> John-Mark Gurney
>>
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>
>
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