1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
|
Return-Path: <rusty@gandalf.ozlabs.org>
Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137])
by lists.linuxfoundation.org (Postfix) with ESMTP id 97BB1C000B
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 16 Feb 2022 03:45:53 +0000 (UTC)
Received: from localhost (localhost [127.0.0.1])
by smtp4.osuosl.org (Postfix) with ESMTP id 9385A4161C
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 16 Feb 2022 03:45:53 +0000 (UTC)
X-Virus-Scanned: amavisd-new at osuosl.org
X-Spam-Flag: NO
X-Spam-Score: -1.652
X-Spam-Level:
X-Spam-Status: No, score=-1.652 tagged_above=-999 required=5
tests=[BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25,
SPF_HELO_PASS=-0.001, SPF_PASS=-0.001] autolearn=no autolearn_force=no
Received: from smtp4.osuosl.org ([127.0.0.1])
by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024)
with ESMTP id 7qBIvzru57qV
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 16 Feb 2022 03:45:52 +0000 (UTC)
X-Greylist: delayed 18:59:16 by SQLgrey-1.8.0
Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76])
by smtp4.osuosl.org (Postfix) with ESMTPS id C707E415E9
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 16 Feb 2022 03:45:51 +0000 (UTC)
Received: by gandalf.ozlabs.org (Postfix, from userid 1011)
id 4Jz3lF5Mcbz4xmx; Wed, 16 Feb 2022 14:45:45 +1100 (AEDT)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Jeremy Rubin <jeremy.l.rubin@gmail.com>
In-Reply-To: <CAD5xwhi4y1NiZ__c1WY-rCV3XBzN5yxY1Zox6Mc1FTjxUhXK9A@mail.gmail.com>
References: <CAMZUoK=pkZuovtifBzdqhoyegzG+9hRTFEc7fG9nZPDK4KbU3w@mail.gmail.com>
<87leymuiu8.fsf@rustcorp.com.au>
<CAD5xwhgP2_51Dvar0f1tsMrCXZ61W9-HnLgR45D-54Oc7-X1ag@mail.gmail.com>
<87k0dwr015.fsf@rustcorp.com.au>
<CAD5xwhi4y1NiZ__c1WY-rCV3XBzN5yxY1Zox6Mc1FTjxUhXK9A@mail.gmail.com>
Date: Wed, 16 Feb 2022 12:56:14 +1030
Message-ID: <87a6err1h5.fsf@rustcorp.com.au>
MIME-Version: 1.0
Content-Type: text/plain
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] TXHASH + CHECKSIGFROMSTACKVERIFY in lieu of CTV
and ANYPREVOUT
X-BeenThere: bitcoin-dev@lists.linuxfoundation.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Bitcoin Protocol Discussion <bitcoin-dev.lists.linuxfoundation.org>
List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/bitcoin-dev>,
<mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=unsubscribe>
List-Archive: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/>
List-Post: <mailto:bitcoin-dev@lists.linuxfoundation.org>
List-Help: <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=help>
List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>,
<mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=subscribe>
X-List-Received-Date: Wed, 16 Feb 2022 03:45:53 -0000
Jeremy Rubin <jeremy.l.rubin@gmail.com> writes:
> Hi Rusty,
>
> Please see my post in the other email thread
> https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-February/019886.html
>
> The differences in this regard are several, and worth understanding beyond
> "you can iterate CTV". I'd note a few clear examples for showing that "CTV
> is just as powerful" is not a valid claim:
>
> 1) CTV requires the contract to be fully enumerated and is non-recursive.
> For example, a simple contract that allows n participants to take an action
> in any order requires factorially many pre-computations, not just linear or
> constant. For reference, 24! is about 2**80. Whereas for a more
> interpretive covenant -- which is often introduced with the features for
> recursion -- you can compute the programs for these addresses in constant
> time.
> 2) CTV requires the contract to be fully enumerated: For example, a simple
> contract one could write is "Output 0 script matches Output 1", and the set
> of outcomes is again unbounded a-priori. With CTV you need to know the set
> of pairs you'd like to be able to expand to a-priori
> 3) Combining 1 and 2, you could imagine recursing on an open-ended thing
> like creating many identical outputs over time but not constraining what
> those outputs are. E.g., Output 0 matches Input 0, Output 1 matches Output
> 2.
Oh agreed. It was distinction of "recursive" vs "not recursive" which
was less useful in this context.
"limited to complete enumeration" is the more useful distinction: it's a
bright line between CTV and TXHASH IMHO.
> I'll close by repeating : Whether that [the recursive/open ended
> properties] is an issue or not precluding this sort of design or not, I
> defer to others.
Yeah. There's been some feeling that complex scripting is bad, because
people can lose money (see the various attempts to defang
SIGHASH_NOINPUT). I reject that; since script exists, we've crossed the
Rubicon, so let's make the tools as clean and clear as we can.
Cheers!
Rusty.
|
