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Date: Sat, 6 Jun 2015 18:20:41 +0200
Message-ID: <CAPswA9wpynPn+HHzL0aTnrWKn3thKXwEfG459TTByX3QcYRubg@mail.gmail.com>
From: Kalle Rosenbaum <kalle@rosenbaum.se>
To: Pieter Wuille <pieter.wuille@gmail.com>
Content-Type: text/plain; charset=UTF-8
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] BIP for Proof of Payment
Precedence: list

>> The idea is to simplify implementation. Existing software can be used
>> as is to sign and validate PoPs. But I do agree that it would be a
>> cleaner specification if we would make the PoP invalid as a
>> transaction. I'm open to changes here. I do like the idea to prepend a
>> constant string. But that would require changes in transaction signing
>> and validation code, wouldn't it?
>
>
> Yes, of course. An alternative is adding a 21M BTC output at the end, or
> bitflipping the txin prevout hashes, or another reversible transformation on
> the transaction data that is guaranteed to invalidate it.

If we do decide to make Pops invalid as transactions, there are a lot
of ways to do that. I guess the main question is if we should make
Pops invalid as transactions or not. So far I prefer to keep them
valid for the above reason.

>
> I think that the risk of asking people to sign something that is not an
> actual transaction, but could be used as one, is very scary.
>

I would feel comfortable doing it. It's just a matter of trusting your
wallet, which you already do with your ordinary transactions.

>>
>> > Also, I would call it "proof of transaction intent", as it's a
>> > commitment to
>> > a transaction and proof of its validity, but not a proof that an actual
>> > transaction took place, nor a means to prevent it from being double
>> > spent.
>>
>>
>> Naming is hard. I think a simpler name that explains what its main
>> purpose is (prove that you paid for something) is better than a name
>> that exactly tries to explain what it is.
>
>
> "Proof of Payment" indeed does make me think it's something that proves you
> paid. But as described, that is not what a PoP does. It proves the ability
> to create a particular transaction, and committing to it. There is no actual
> payment involved (plus, payment makes me think you're talking about BIP70
> payments, not simple Bitcoin transactions).
>
>>
>> "Proof of transaction
>> intent" does not help me understand what this is about. But I would
>> like to see more name suggestions. The name does not prevent people
>> from using it for other purposes, ie internet over telephone network.
>
>
> I don't understand why something like "Proof of Transaction Intent" would be
> incompatible with internet over telephone network either...
>

No, I meant that it's ok to call it Proof of Payment even though
people may use it for other stuff.

> --
> Pieter
>