Subject: Re: [Bitcoin-development] instant confirmation via payment protocol backwards compatible proto buffer extension

From: Lawrence Nahum <[email-masked]>
Date: Mon, 16 Jun 2014 17:05:27 +0000 (UTC)

Mike Hearn <mike <at> plan99.net> writes:

> Sure. I buy this. Although the credit card market is a great example of 
what we don't want: a stagnant duopoly of trusted third parties who 
rampantly abuse their position. So I'd hope we see either (a) nobody really 
caring about this BIP because Bitcoin gives good enough double spend 
protection or (b) lots of anti-double-spend providers (hundreds seems fine).

Maybe hundreds, maybe less. I can imagine there would/could be local ones.
It's not the same as credit cards though: it's an open protocol with 
explicit intent from all parties and no forced fees for normal transactions 
- just for instant ones.

> No, I will never wait. Neither me nor the merchant wants to me to be 
pointlessly hanging around for an hour. The alternative is to pay by credit 
card or cash. Outside of experiments there is no such thing as a shop that 
only accepts only Bitcoin and will require me to wait for a block because I 
didn't use a TTP to guarantee anti-double spends.

I tend to agree but _today_ people are trying to use bitcoin and are waiting 
and waiting ..

> So this seems like a fundamental problem to me: having the ability to say, 
"here is a proof I won't double spend" is fine, but it doesn't achieve 
anything if the merchant would have sold me the goods in return for a normal 
Bitcoin tx anyway, which in practice they always will because this system 
starts out from zero users and would have to work upwards. I especially will 
never use this system if I have to pay for it - I'd much rather just put my 
money into a wallet that can't generate these proofs and pay the sticker 
price.

This is a cultural thing. In some places if you pay by cards you pay extra.
I think it may be good to support both models but I like better the 
transparent one even if I'm going to admit that the least transparent one 
may be more attractive as it fools consumers.

> Maybe what this BIP needs is an extra field that lets the merchant say, I 
will give you a discount of X satoshis if you give me a no-double-spends 
proof. In other words invert it: the sticker price is what normal Bitcoin 
transactions cost, and then your wallet shows you the regular BIP70 price 
minus the discount plus the third parties fee as what you finally pay. I 
compare it to the sticker price the merchant is asking and if it's lower I'm 
happy, and if it's higher my wallet would automatically avoid using the TTP 
because I don't want to ever pay more, only less.
> The market would then figure out if the fees the TTP charges are worth the 
lower losses due to double spending fraud.

I think this is worth discussing further. Would love also more input from 
other people on this.