Subject: Re: [Bitcoin-development] blind symmetric commitment for stronger byzantine voting resilience (Re: bitcoin taint & unilateral revocability)

From: Mike Hearn <[email-masked]>
Date: Wed, 15 May 2013 19:22:51 -0700

Conceptually it sounds a lot like ZeroCoin (not in implementation)?

I'm not really convinced miner cartels that try to exclude transactions are
likely to be a big deal, but such schemes could I suppose be kept in a back
pocket in case one day I'm proven wrong.

On Wed, May 15, 2013 at 6:39 PM, Gregory Maxwell <[email-masked]> wrote:

> On Wed, May 15, 2013 at 6:24 PM, Gavin <[email-masked]> wrote:
> > Busy with pre-conference stuff, not following details of this
> conversation...
> >
> > ... but it sounds a lot like the "guy fawkes" protocol Zooko was
> thinking about a year or so ago.
>
> Sort of, but in a guy fawkes signature you use the commitment to hide
> the preimage that proves you had authority to spend a coin.   Adam
> proposes you do this in order to hide _which coin you're spending_.
>
> This has obvious anti-DOS complications, but Adam deftly dodged my
> initial attempts to shoot him down on these grounds by pointing out
> that you could mix blinded and blinded inputs and have priority and
> transaction fees come from only the unblinded ones.
>
> Effectively,  it means that so long as you could convince the network
> to let you spend some coins, you could also spend other ones along for
> the ride and the network wouldn't know which ones those were until it
> was too late for it to pretend it never saw them.
>
> I think there are all kinds of weird economic implications to this— a
> blinded payment would seem to have a different utility level to an
> unblinded one: you can't use it for fees— except you can unblind it at
> any time.  And the discontinuousness  ("two types of inputs") and that
> it would enable mining gibberish (though perhaps not data storage, if
> you see my preimage solution to that) seems awkward and I think I have
> to spend some time internalizing it before I can really think through
> the implications.
>
>
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