Subject: Re: [Bitcoin-development] BIP70 extension to allow for identity delegation

From: Mike Hearn <[email-masked]>
Date: Sun, 2 Mar 2014 17:14:43 +0100

On Sun, Mar 2, 2014 at 4:20 PM, Andreas Schildbach <[email-masked]>wrote:

> I somehow think that it is too early for this heavy kind of extension,
> given that the first version of BIP70 isn't even deployed widely let
> alone *used*.
>

Definitely agree - like I said, I publish this only because I keep getting
asked about it.

> By reading your proposal I get the idea that the current spec doesn't
> allow two (or three) different PKIs at once

That's right. There's little point in having multiple PKI's simultaneously,
that's why it doesn't allow it.

This one is a special case because it doesn't replace but rather
specialises and extends the existing PKI. Old clients that don't understand
it would still show something useful and by upgrading you get better
output. Actually you get closer to the output you're supposed to get.

That's going to be rare though, I think. Generally you wouldn't want to
have multiple PKIs in use simultaneously for the same payment request.

> I would prefer if your fix would stay local to X.509 (and thus only
> change X.509 specific structs rather than the top-level PaymentRequest).
>

It can be done but only by sacrificing backwards compatibility, which
doesn't seem worth it to me. It's hardly a big deal to have two signature
fields. The rest is all localised to the X509 parts.