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From: Andrew Poelstra <apoelstra@wpsoftware.net>
To: Anthony Towns <aj@erisian.com.au>,
	Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Soft-forks and schnorr signature aggregation
Date: Wed, 21 Mar 2018 12:45:21 +0000	[thread overview]
Message-ID: <20180321124521.GI9082@boulet.lan> (raw)
In-Reply-To: <20180321040618.GA4494@erisian.com.au>

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On Wed, Mar 21, 2018 at 02:06:18PM +1000, Anthony Towns via bitcoin-dev wrote:
> 
> That leads me to think that interactive signature aggregation is going to
> take a lot of time and work, and it would make sense to do a v1-upgrade
> that's "just" Schnorr (and taproot and MAST and re-enabling opcodes and
> ...) in the meantime. YMMV.
>

Unfortunately I agree. Another complication with aggregate signatures is
that they complicate blind signature protocols such as [1]. In particular
they break the assumption "one signature can spend at most one UTXO"
meaning that a blind signer cannot tell how many coins they're authorizing
with a given signature, even if they've ensured that the key they're using
only controls UTXOs of a fixed value.

This seems solvable with creative use of ZKPs, but the fact that it's even
a problem caught me off guard, and makes me think that signature aggregation
is much harder to think about than e.g. Taproot which does not change
signature semantics at all.


Andrew



[1] https://github.com/jonasnick/scriptless-scripts/blob/blind-swaps/md/partially-blind-swap.md



-- 
Andrew Poelstra
Mathematics Department, Blockstream
Email: apoelstra at wpsoftware.net
Web:   https://www.wpsoftware.net/andrew

"A goose alone, I suppose, can know the loneliness of geese
 who can never find their peace,
 whether north or south or west or east"
       --Joanna Newsom


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  parent reply	other threads:[~2018-03-21 12:45 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-21  4:06 [bitcoin-dev] Soft-forks and schnorr signature aggregation Anthony Towns
2018-03-21  7:53 ` ZmnSCPxj
2018-03-21 11:21   ` Anthony Towns
2018-03-21 23:28     ` ZmnSCPxj
2018-03-21 12:45 ` Andrew Poelstra [this message]
2018-03-22  0:47 Bram Cohen
2018-03-27  6:34 ` Anthony Towns
2018-03-28  3:19   ` Bram Cohen

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