Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of gmail.com
	designates 209.85.215.175 as permitted sender)
	client-ip=209.85.215.175; envelope-from=andyparkins@gmail.com;
	helo=mail-ea0-f175.google.com; 
From: Andy Parkins <andyparkins@gmail.com>
To: bitcoin-development@lists.sourceforge.net
Date: Tue, 27 Nov 2012 17:03:39 +0000
User-Agent: KMail/1.13.7 (Linux/3.2.0-3-686-pae; KDE/4.8.4; i686; ; )
References: <CABsx9T0PsGLEAWRCjEDDFWQrb+DnJWQZ7mFLaZewAEX6vD1eHw@mail.gmail.com>
In-Reply-To: <CABsx9T0PsGLEAWRCjEDDFWQrb+DnJWQZ7mFLaZewAEX6vD1eHw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: Text/Plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Message-Id: <201211271703.39282.andyparkins@gmail.com>
Subject: Re: [Bitcoin-development] Payment Protocol Proposal:
	Invoices/Payments/Receipts
Precedence: list

On Monday 26 November 2012 22:37:31 Gavin Andresen wrote:

> x509chain: one or more DER-encoded X.509 certificates that identifies
> the merchant. See the "Certificates" section below for details.

Personally, I'd like to see fewer implicit ties to X509.  With X509 as one 
option.  For example, I'd much prefer to see a doorway to the future left open 
like this:

    message Invoice {
        repeated bytes issuerIdentityType;
        repeated bytes issuerIdentityBytes;

or similar, instead of "x509chain".

In particular two additional identification types:

 - GnuPG (obviously)
 - Hash based

The hash-based system would be there as a method of leveraging an existing 
trusted connection, without needing to get into the nitty-gritty of 
certificates.  For example, I am paying for something on a web site; I 
presumably already have a secure connection that I trust to that site.  That 
site can issue me an invoice (which is to be sent to the bitcoin client) _and_ 
a hash of the certificate on the same page.

I trust that hash because I received it over a secure connection from a 
trusted source.  When my bitcoin client pops up with the received invoice, it 
shows me the hash of the invoice, and I can be sure that it is from the web 
site I thought it was from.

Imagine I'm a (very) small business, I have two or three customers.  I want to 
email one of my customers an invoice.  I don't want to have to get an X509 
certificate, and I don't necessarily know how.  However, I can ring my 
customer up and say "I've generated an invoice with my bitcoin client, it is 
hashed A7DE-521X-9977.  Write that down and confirm it when you get my 
invoice".  Alternatively, I might attach a file called
invoice-A7DE-521X-9977.bitinv to a signed GnuPG email.  The receipient can 
easily confirm I sent it because the filename must match the contents and 
GnuPG protects against tampering.


Andy

-- 
Dr Andy Parkins
andyparkins@gmail.com