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
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
Return-Path: <apoelstra@wpsoftware.net>
Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133])
by lists.linuxfoundation.org (Postfix) with ESMTP id 97F65C0032
for <bitcoin-dev@lists.linuxfoundation.org>;
Tue, 24 Oct 2023 01:17:31 +0000 (UTC)
Received: from localhost (localhost [127.0.0.1])
by smtp2.osuosl.org (Postfix) with ESMTP id 720E641960
for <bitcoin-dev@lists.linuxfoundation.org>;
Tue, 24 Oct 2023 01:17:31 +0000 (UTC)
DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 720E641960
Authentication-Results: smtp2.osuosl.org;
dkim=pass (2048-bit key) header.d=mail.wpsoftware.net
header.i=@mail.wpsoftware.net header.a=rsa-sha256 header.s=default
header.b=ftGtfe3s
X-Virus-Scanned: amavisd-new at osuosl.org
X-Spam-Flag: NO
X-Spam-Score: -1.107
X-Spam-Level:
X-Spam-Status: No, score=-1.107 tagged_above=-999 required=5
tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1,
RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001]
autolearn=no autolearn_force=no
Received: from smtp2.osuosl.org ([127.0.0.1])
by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024)
with ESMTP id G9Vr4zhoniCa
for <bitcoin-dev@lists.linuxfoundation.org>;
Tue, 24 Oct 2023 01:17:30 +0000 (UTC)
Received: from mail.wpsoftware.net (unknown [66.183.0.205])
by smtp2.osuosl.org (Postfix) with ESMTP id 4A6AD4012B
for <bitcoin-dev@lists.linuxfoundation.org>;
Tue, 24 Oct 2023 01:17:30 +0000 (UTC)
DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 4A6AD4012B
Received: from camus (camus-andrew.lan [192.168.0.190])
by mail.wpsoftware.net (Postfix) with ESMTPSA id 777CE400C6;
Tue, 24 Oct 2023 01:17:29 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mail.wpsoftware.net;
s=default; t=1698110249;
bh=FcCap2kd7NwOpSP0BgBw6fVDo7VwetGVvAst/dePL7M=;
h=Date:From:To:Cc:Subject:References:In-Reply-To;
b=ftGtfe3sBL9P3lD12GTgKvD9smJFsLsO2dmqKFADwMKSzUu+HJh9/BRrLsa3V3BVb
Bs70TMraXa46IJP+m5QZCNz33ffX0cE1KlxmCIyKPVBCZwVSSxpo+qiUmnkz/4MJ8A
QQwngkqOnq15S66MAytI/6XaxjKjB8kxMGAkuHLBeCIsiGQ0dqOOGG/S+gx9xFvSho
ElZuNxavLYnx4Qc0Q6z8B0DkqjiM0XtZ0vk7Vf38qBcqkO0uPbNsJLWpzSxI+zdtYG
4MHhKcouG6JAGaKwgTfks9EEHiP6r5KlbKn/zrRyqpEzI29DM37L+FVZEKCd1NoxzV
YTplUFhoST/KQ==
Date: Tue, 24 Oct 2023 01:17:28 +0000
From: Andrew Poelstra <apoelstra@wpsoftware.net>
To: Rusty Russell <rusty@rustcorp.com.au>
Message-ID: <ZTcbKM+XTCaJ2kIP@camus>
References: <CAEM=y+XDB7GGa5BTAWrQHqTqQHBE2VRyd7VWjEb+zCOMzRP+Lg@mail.gmail.com>
<871qdmulvt.fsf@rustcorp.com.au> <ZTZ4H2y6+5pxRcs/@camus>
<871qdku9pj.fsf@rustcorp.com.au>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha256;
protocol="application/pgp-signature"; boundary="oYBV971ACDRmjKTB"
Content-Disposition: inline
In-Reply-To: <871qdku9pj.fsf@rustcorp.com.au>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Proposed BIP for OP_CAT
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: Tue, 24 Oct 2023 01:17:31 -0000
--oYBV971ACDRmjKTB
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable
On Tue, Oct 24, 2023 at 11:18:24AM +1030, Rusty Russell wrote:
> Andrew Poelstra <apoelstra@wpsoftware.net> writes:
> >> 3. Should we restrict elsewhere instead? After all, OP_CAT doesn't
> >> change total stack size, which is arguably the real limit?
> >>=20
> >
> > Interesting thought. Right now the stack size is limited to 1000
> > elements of 520 bytes each, which theoretically means a limit of 520k.
> > Bitcoin Core doesn't explicitly count the "total stack size" in the
> > sense that you're suggesting; it just enforces these two limits
> > separately.
>=20
> BTW, I'm just learning of the 1000 element limit; I couldn't see it on
> scanning BIP-141.
>
This limit is very old and predates segwit. It might predate P2SH.
> > I think trying to add a "total stack size limit" (which would have to
> > live alongside the two existing limits; we can't replace them without
> > a whole new Tapscript version) would add a fair bit of accounting
> > complextiy and wind up touching almost every other opcode...probably
> > not worth the added consensus logic.
>=20
> Simplest thing I can come up with:
>=20
> - instead of counting simple stack depth, count each stack entry as
> (1 + <size>/520) entries? You can still only push 520 bytes, so you
> can only make these with OP_CAT.
>=20
> Looking in interpreter.cpp, `stack` and `altstack` now need to be
> objects to count entries differently (not vectors), but it seems like
> it'd be simple enough, and the logic could be enabled unconditionally
> since it Cannot Be Violated prior to OP_CAT.
>
I had a similar thought. But my feeling is that replacing the stack
interpreter data structure is still too invasive to justify the benefit.
Also, one of my favorite things about this BIP is the tiny diff.
--=20
Andrew Poelstra
Director of Research, Blockstream
Email: apoelstra at wpsoftware.net
Web: https://www.wpsoftware.net/andrew
The sun is always shining in space
-Justin Lewis-Webster
--oYBV971ACDRmjKTB
Content-Type: application/pgp-signature; name="signature.asc"
-----BEGIN PGP SIGNATURE-----
iQEzBAEBCAAdFiEEkPnKPD7Je+ki35VexYjWPOQbl8EFAmU3GycACgkQxYjWPOQb
l8FCngf+JTyBmW6E3+rLfgQh7B3baEcsRiHHxsCOUgSG/JHmd6xZaG1oiYulLDry
mnefhmyJ+uhAAod+f+7Lsrutvbraotsto+vxoX84pQ+TIreRJL9OkslIdki6bH5W
MemtkLUSB1sbNWvl0+ENrB5KacV87mU9HwhNKKggrDedHpDdVYRrc9/GOsFhTHiv
SYkSEMGvExO4C16ywokybvsIevr8rCRUDhflHkBlzXW+48jL9cmIJ0ypgX0Y9qgO
c2J0Pd+eIsqRgckcI7646DWqoM487hFDVNhjW94jaSWin1sOdfH237p8WECfwOPu
1RLJ7WnU0jkc+Gats+Rijj7bdvVE0g==
=Jt3N
-----END PGP SIGNATURE-----
--oYBV971ACDRmjKTB--
|
