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From: Johnson Lau <jl2012@xbt•hk>
To: Luke Dashjr <luke@dashjr•org>,
	bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Version 1 witness programs (first draft)
Date: Mon, 2 Oct 2017 05:32:56 +0800	[thread overview]
Message-ID: <30B31B43-B603-4793-BDFB-B7E25FD96D1B@xbt.hk> (raw)
In-Reply-To: <201710010113.30518.luke@dashjr.org>

So there are 3 proposals with similar goal but different designs. I try to summarise some questions below:

1. How do we allow further upgrade within v1 witness? Here are some options:
a. Minor version in witness. (Johnson / Luke) I prefer this way, but we may end up with many minor versions.
b. OP_RETURNTRUE (Luke). I proposed this in an earlier version of BIP114 but now I think it doesn’t interact well with signature aggregation, and I worry that it would have some other unexpected effects.
c. Generalised NOP method: user has to provide the returned value, so even VERIFY-type code could do anything

2. Do we want to allow signature-time commitment of extra scripts?
I think all proposals allow this, just with different way
a. Tail-call semantics with CHECKSIGFROMSTACK (Mark). I think this is too rigid as it works only with specially designed scriptPubKey
b. scriptWitCode: extra scripts are put in some fixed location in witness (Johnson). This makes sure static analysability.
c. Extra-data as script in OP_CHECKSIG (Luke)

3. Do we want to allow static analysis of sigop?
BIP114 and the related proposals are specifically designed to allow static analysis of sigop. I think this was one of the main reason of OP_EVAL not being accepted. This was also the main reason of Ethereum failing to do a DAO hacker softfork, leading to the ETH/ETC split. I’m not sure if we really want to give up this property. Once we do it, we have to support it forever.

——
Johnson


  parent reply	other threads:[~2017-10-01 21:33 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-01  1:13 Luke Dashjr
2017-10-01  2:23 ` Mark Friedenbach
2017-10-01  2:47   ` Luke Dashjr
2017-10-01  5:04     ` Mark Friedenbach
2017-10-01 11:22       ` Felix Weis
2017-10-01 17:36         ` Luke Dashjr
2017-10-01 19:05       ` Russell O'Connor
2017-10-01 19:27         ` Mark Friedenbach
2017-10-01 19:41           ` Russell O'Connor
2017-10-01 20:39             ` Mark Friedenbach
2017-10-01 20:43               ` Luke Dashjr
2017-10-02 20:38               ` Russell O'Connor
2017-10-01 18:34 ` Mark Friedenbach
2017-10-01 21:32 ` Johnson Lau [this message]
2017-10-02  0:35   ` Mark Friedenbach
2017-10-02  2:56     ` Luke Dashjr
2017-10-02  9:09       ` Sjors Provoost
2017-10-02  0:45   ` Luke Dashjr
2017-10-05 20:33 ` Mark Friedenbach
2017-10-05 21:28   ` Russell O'Connor

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