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Date: Fri, 12 Sep 2014 11:43:32 -0700
Message-ID: <CACq0ZD6ocZ62rvRQaxQZ3moH3kC-uK_US3+p67Y+8bMJB_-b5A@mail.gmail.com>
From: Aaron Voisine <voisine@gmail.com>
To: Mike Hearn <mike@plan99.net>
Content-Type: text/plain; charset=UTF-8
Cc: "bitcoin-development@lists.sourceforge.net"
	<bitcoin-development@lists.sourceforge.net>,
	Andreas Schildbach <andreas@schildbach.de>
Subject: Re: [Bitcoin-development] BIP72 amendment proposal
Precedence: list

Are there any circumstances where the payment request object might be
served over a different domain than the CNAME of the object's signer?

BIP72 states "Bitcoin wallets must support fetching PaymentRequests
via http and https protocols;". If the request object is signed by the
owner of the domain, then the worst an attacker who doesn't have the
signing key can do is replace the request with another validly signed
request intended for someone else, but that could be the attacker's
own product order, tricking someone else into paying for it.

Should BIP72 require that signed payment requests be from the same
domain, and also require https?

Aaron

Aaron Voisine
breadwallet.com


On Fri, Sep 12, 2014 at 9:31 AM, Mike Hearn <mike@plan99.net> wrote:
> Putting aside the question of necessity for a moment, a more efficient
> approach to this would be;
>
> Add another marker param like &s to the end of the URL
> Add another field to PaymentRequest that contains an ECC signature
> calculated using the public key that hashes to the address in the URI
> Upgraded wallets look for the additional param and if it's there, expect to
> find the PaymentDetails signed with the address key. PKI signing of course
> is still useful to provide an actual identity for receipts, display on
> hardware wallets, dispute mediation etc.
>
> This adds only a few characters to a normal backwards-compatible QR code,
> and is not hard to implement.
>
>
> On Fri, Sep 12, 2014 at 5:37 PM, Mike Hearn <mike@plan99.net> wrote:
>>>
>>> That way we leave up to implementers to experiment with different
>>> lengths and figure out what the optimum is
>>
>>
>> Ah, that's a good suggestion if we do go this way.
>
>
>
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