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Date: Wed, 24 Aug 2011 11:12:10 -0400
Message-ID: <CABsx9T1uw43JuvhEmJP0KCyojsDi1r7v6BaLBHz7wWazduE5iw@mail.gmail.com>
From: Gavin Andresen <gavinandresen@gmail.com>
To: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
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Subject: [Bitcoin-development] New standard transaction types: time to
	schedule a blockchain split?
Precedence: list

It seems to me the fastest path to very secure, very-hard-to-lose
bitcoin wallets is multi-signature transactions.

To organize this discussion: first, does everybody agree?

ByteCoin pointed to a research paper that gives a scheme for splitting
a private key between two people, neither of which every knows the
full key, but, together, both can DSA-sign transactions.  That's very
cool, but it involves high-end cutting-edge crypto like zero-knowledge
proofs that I know very little about (are implementations available?
are they patented?  have they been thoroughly vetted/tested?  etc).
So I'm assuming that is NOT the fastest way to solving the problem.

If anybody has some open-source, patent-free, thoroughly-tested code
that already does DSA-key-splitting, speak up please.


I've been trying to get consensus on low-level 'standard' transactions
for transactions that must be signed by 2 or 3 keys; current draft
proposal is here:
 https://gist.github.com/39158239e36f6af69d6f
and discussion on the forums here:
 https://bitcointalk.org/index.php?topic=38928.0
... and there is a pull request that is relevant here:
 https://github.com/bitcoin/bitcoin/pull/319


I still think it is a good idea to enable a set of new 'standard'
multisignature transactions, so they get relayed and included into
blocks.  I don't want to let "the perfect become the enemy of the
good" -- does anybody disagree?

The arguments against are that if the proposed standard transactions
are accepted, then the next step is to define a new kind of bitcoin
address that lets coins be deposited into a multisignature-protected
wallet.

And those new as-yet-undefined bitcoin addresses will have to be 2 or
3 times as big as current bitcoin addresses, and will be incompatible
with old clients.

So, if we are going to have new releases that are incompatible with
old clients why not do things right in the first place, implement or
enable opcodes so the new bitcoin addresses can be small, and schedule
a block chain split for N months from now.

My biggest worry is we'll say "Sure, it'll only take a couple days to
agree on how to do it right" and six months from now there is still no
consensus on exactly which digest function should be used, or whether
or not there should be a new opcode for arbitrary boolean expressions
involving keypairs.  And people's wallets continue to get lost or
stolen.


-- 
--
Gavin Andresen