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Date: Thu, 29 Nov 2012 13:53:30 -0500
From: Roy Badami <roy@gnomon.org.uk>
To: Mike Hearn <mike@plan99.net>, g@gnomon.org.uk
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Payment Protocol Proposal:
 Invoices/Payments/Receipts
Precedence: list

On Thu, Nov 29, 2012 at 06:31:24PM +0100, Mike Hearn wrote:
> > I'd still like to understand the rationale for having the merchant
> > broadcast the transaction
> 
> There are several reasons for this:

[snip]

All good reasons, thanks for the explanation.

Though I still like my idea of a ValidatePurchase message that allows
a buyer to ask a merchant "would you accept this payment?" without
actually supplying a signed transaction.  Make it optional if you care
about minimising the number of round trips, e.g. for fast NFC
payments.

Having such a message reduces the extent to which you need to trust
the merchant not to spend a transaction that they've rejected.  (And
in the non-Internet connected case this is particularly useful since
the client won't have the ability to broadcast a pay-to-self
transaction.)

roy