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
101
102
103
104
105
106
107
108
|
Return-Path: <pieter.wuille@gmail.com>
Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org
[172.17.192.35])
by mail.linuxfoundation.org (Postfix) with ESMTPS id 0838DE04
for <bitcoin-dev@lists.linuxfoundation.org>;
Fri, 9 Aug 2019 18:30:09 +0000 (UTC)
X-Greylist: whitelisted by SQLgrey-1.7.6
Received: from mail-ot1-f54.google.com (mail-ot1-f54.google.com
[209.85.210.54])
by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 9148382F
for <bitcoin-dev@lists.linuxfoundation.org>;
Fri, 9 Aug 2019 18:30:08 +0000 (UTC)
Received: by mail-ot1-f54.google.com with SMTP id l15so136217135otn.9
for <bitcoin-dev@lists.linuxfoundation.org>;
Fri, 09 Aug 2019 11:30:08 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025;
h=mime-version:references:in-reply-to:from:date:message-id:subject:to;
bh=u4h2lffoLHiq7mhvHBTIYTCvQ6Czky3Wfa+FEk0mIlo=;
b=oDf4t2dnshhHg1qcTljKWZR9azRsGQwK7wsCcMzeQT7gmEjv8nHshwlAwnlNP1MR0S
O+/wgKHPTGajINw/VZW6Q5MJGAumZjKnXajmbOqgYl38fbRUsjgGHIg2TzW35jkOobXq
GZs6EjWd7IAfCt5Xn+dJ1tybT2TEq0+z8M4XLq8OBWJVmA7GsN8rMK9hhlv1cBlgqQuo
A/vEwf61VxLzOrTfNEL9CAlLafUmHeWmz5z0duUUZrqo19V+M+I3QdAl2y2LoeNO1hf8
p9XqXXnYAnFpKFtYEJZkianllK9uE/moVYXb2K8MQ+BK2chpR/nkORpvTExQGsdVVypD
0oIQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20161025;
h=x-gm-message-state:mime-version:references:in-reply-to:from:date
:message-id:subject:to;
bh=u4h2lffoLHiq7mhvHBTIYTCvQ6Czky3Wfa+FEk0mIlo=;
b=DzNrwXxvMbEVQBsRAaaJ6jDQaJrMQAxY2sXVpywevWa6sT3Vuu/LHS0wrmREUePgdJ
dA5Q8jBfB6UH+GcB4NJmhukjtsw0b5K7dilIPcyBdsUD5Me+1s5uOiTKXgc/rkVpysKi
H6IqNH8Im9x6pAMjb4w94j+h4QkUoWg/IHOK4yy+10c09DDQYpw7cGNffIz1W4be6WS5
l572FhEqFK72y91h/ClJ2ojRMvpKTPqjvuR+M2cYr+eBxrp3toHTluytQeTRJlrnkKgG
Bu6Kualk6NAN6E++HgiLUcqptWEG1i0zwNbgxi3Hm2naoxejk5vmpI5ZN2Q6ZujJxST/
a4ow==
X-Gm-Message-State: APjAAAUaOnELlp/tu3cOCP2ZW/NV78ydf4JnqLTKEggjSRkhFKx+a55H
PaEBRJmGDm2MvoLRF85qx6zFtCFzU9f5iXW4+RKmzK2E
X-Google-Smtp-Source: APXvYqy8Jj6Ci4NPaDpdqz5eEctdeOJ2RhvksW+Hrzk/SCdt1AsAClpvhJJ/jqWn4qpBZXxJh3pP+iwJcVSL/muD6p0=
X-Received: by 2002:a05:6830:144e:: with SMTP id
w14mr17694730otp.10.1565375407781;
Fri, 09 Aug 2019 11:30:07 -0700 (PDT)
MIME-Version: 1.0
References: <CALN7hCJ7dCER9zaQbXvT4AVt95cZwBsQcTX8XvvZwF-1xa-V4w@mail.gmail.com>
In-Reply-To: <CALN7hCJ7dCER9zaQbXvT4AVt95cZwBsQcTX8XvvZwF-1xa-V4w@mail.gmail.com>
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Fri, 9 Aug 2019 11:29:55 -0700
Message-ID: <CAPg+sBgyhjRmVdtC1bGWkpaTtMqQRsCqKjFB=LU_fcMYUJc6jA@mail.gmail.com>
To: Elichai Turkel <elichai.turkel@gmail.com>,
Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: text/plain; charset="UTF-8"
X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED,
DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM,
RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1
X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on
smtp1.linux-foundation.org
Subject: Re: [bitcoin-dev] Taproot proposal
X-BeenThere: bitcoin-dev@lists.linuxfoundation.org
X-Mailman-Version: 2.1.12
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: Fri, 09 Aug 2019 18:30:09 -0000
On Fri, 9 Aug 2019 at 08:02, Elichai Turkel via bitcoin-dev
<bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> Hi,
Since the idea of implicitly even pubkeys has potentially more general
implications, I've started a separate thread [1] about that idea.
> I want to add to John Newbery's suggestion of using implicit even/odd only public keys and tweaked public keys in taproot and suggest the following:
> If everything is implicit then the only reason for the first byte of the control block(`c[0]`) is the tapscript leaf version.
That's unfortunately not correct. If we want to maintain
batch-verifiability of the taproot tweaking (the Q = P + H(P,m)G
relation), we still need a bit in the control block to convey whether
a negation was necessary to make P+H(P,m)G even, even if P and Q both
have implied-even Y coordinates. Not doing that would require
exploring 2^n combinations to batch verify n relations, obviously
destroying any performance savings the batch verification had in the
first place.
> I suggest that this is moved to be the first OP_CODE of the tapscript itself (i.e. OP_0/OP_1 etc.)
> That way having the script *tells* you what does it mean without needing to check the control block.
> That way there's a separation between the tapscript+leaf version and the control block being the merkle path to the script.
If we keep the leaf version idea (it's possible to instead just rely
entirely on OP_SUCCESSx, and drop leaf versions), my preference is to
still keep it separate from script, though just for a fairly banal
reason: that way the script consists entirely of opcodes and can be
treated uniformly by debug tools, rather than needing to treat the
first byte special. I do understand your preference too, but I don't
know how it weighs up.
[1] https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2019-August/017247.html
Cheers,
--
Pieter
|