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Date: Fri, 5 Jul 2013 16:01:40 +0200
From: Adam Back <adam@cypherspace.org>
To: Bitcoin-Dev <bitcoin-development@lists.sourceforge.net>
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Subject: [Bitcoin-development] libzerocoin released,
 what about a zerocoin-only alt-coin with either-or mining
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Hi

I presume everyone saw the announce from Matthew Green & Ian Miers at JHU on
the release of libzerocoin: https://github.com/Zerocoin/libzerocoin

So now that raises the question of how can people experiment with real money
with zerocoin.  I think its fair to summarize there is resistance to merging
into bitcoin as it slows validation, bloats the blockchain, and also a
policy aspect it also imports cryptographic privacy into bitcoin.

On the forum thread on zerocoin math etc I suggested maybe people interested
to explore bitcoin could create an all-zerocoin alt-coin that is either-or
mined and p2p exchangeable for bitcoin.

Do people think that should work?  It seems to me it should with minimal,
bitcoin changes.  I think the rule for either-or mining should be as simple
as skipping the value / double-spend validation of the blocks that are
zerocoin mining blocks.  Obviously zerocoin blocks can themselves end up on
forks, that get resolved, but that fork resolution can perhaps be shared? 
(Because the fork resolution is simply to accept the longest fork).

> what about making an all zerocoin based alt-coin (no bitcoins, nothing but
> zerocoins), that is either-or mined with bitcoin.  Then people can trade
> in and out of zerocoins by buying or selling them for bitcoin with an
> atomic transaction, probably p2p without some trusted exchange like mtgox.
> 
> Either-or mined (as distinct from merge-mined) I mean that each mined coin
> set is either a set of 25 bitcoins or a set of 25 zerocoins.  If its a
> zerocoin set its not a valid bitcoin set, and if its a bitcoin its not a
> valid zerocoin.  I'm not sure the zerocoins or bitcoins have to do much
> with mining events for the other network other than check they have the
> expected number of bits as they wont automatically know how to validate
> the other network.  Some miners may choose to validate both networks, but
> thats a choice for them.
> 
> In that way people can experiment with zerocoin, without bloating the
> block chain, complicating bitcoin, and without slowing validation on the
> bitcoin network.  And the two coins should have approximately the same
> cost (and maybe therefore value, though the price would be subject to
> demand/supply and any taint discount for bitcoins; zerocoins are taint
> free, or perfectly blended taint at least).

Adam