Re: [Acme] ACME signature mechanics

[Phillip Hallam-Baker <[e-mail]>]

On Thu, Dec 18, 2014 at 1:50 PM, Trevor Freeman <[e-mail]
> wrote:
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> Part of the objective here should be to put the end customer in control by
> running their own issue point that is a proxy to a CA or another proxy.
> Binding the authentication to the transport means that the proof of
> possession can only be verified by the proxy which breaks the model.
>
> *[TF] If you trust the proxy enough to terminal the TLS then you trust it
> enough to pass a flag to indicate authentication succeeded*
>
> *Have you considered what value the POP on a pkcs#10 actually delivers? It
> does not show the subject submitting the request is the same as the one in
> control of the key pair. It just proves to the CA the key pair is
> functional.*
>


That is really fuzzy argument there Trevor. Who do you mean by 'you'?

In my model there are two parties, the CA and the Subscriber. Both can have
a proxy but the proxy is trusted by exactly one party. A proxy deployed by
the subscriber for their convenience is not going to be trustworthy as far
as the CA is concerned for proof of possession purposes.

The only circumstance in which the proxy is trusted by both is where they
are the same party. And that is not the main application for ACME.


If this was a transport layer concern then it would have been added to TLS
as an option in 1995. It is an application layer concern, hence the need
for an application layer spec.