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
|
Return-Path: <roconnor@blockstream.io>
Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org
[172.17.192.35])
by mail.linuxfoundation.org (Postfix) with ESMTPS id 6DFD3AC9
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 13 Sep 2017 13:24:37 +0000 (UTC)
X-Greylist: whitelisted by SQLgrey-1.7.6
Received: from mail-wm0-f48.google.com (mail-wm0-f48.google.com [74.125.82.48])
by smtp1.linuxfoundation.org (Postfix) with ESMTPS id CAFCF124
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 13 Sep 2017 13:24:36 +0000 (UTC)
Received: by mail-wm0-f48.google.com with SMTP id i189so6736616wmf.1
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 13 Sep 2017 06:24:36 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=blockstream-io.20150623.gappssmtp.com; s=20150623;
h=mime-version:from:date:message-id:subject:to:cc;
bh=BcXnsI21pyYJTSuNCbZ1xpmttbIOv5qxA+W4joo4E18=;
b=YAhAi6QEMo+kCODSwkNgnF15Q8mKDGHZe989kK3qrcr31k1Lcj/QA0tcKjirqLjOFG
mC+1862RD17Z507GgKQWbgY+/N9w81/Y0+35Fza5jISE2r9IFdxn5TruZewQhU0VYPjy
jXony49H1GH8eEQ8qkbbgRwQ/jTY6IeEN+l34NoYzbqJJC12xsx3LrPVxB9T0d103elP
y+kNJSeJwlHhNJhJ87QXXVhFfJZgImeuExPxoIS28JmLd2PbJMX/jPWWKogzpV81aBMP
GWhjgzdyHzhHvwpRz+NIdptdNLum5XaPLmzvIUVIVN2X0WvmrU9Q53TicuHZDfudK68f
LYmw==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20161025;
h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc;
bh=BcXnsI21pyYJTSuNCbZ1xpmttbIOv5qxA+W4joo4E18=;
b=i03cooRbdWqtsxzz3ApL44K+bjopVo2MATJCx3ZuWQF14G0xNGxG3HT6LNIDlWa4j+
DsFdoRSQfhsNjYA+gCBntaotkGKjFXO+VJ7RpflzZtwQA0zOyOBaFgkRycnOdwsuC5C+
ULeDeKmWXBY9mKeY1OP5JGNGwxK2ywpevZEHuTnB65yuo/E5N5DoM8GyTwvh9CdtkrpJ
mQoUUaDQeEY3dWSIl1a0LqWXWOtIRl9mbvxQFuLHFUvceU8Ygl0Hil3HiPBctlFp9B0E
GVf/RwI0nBvsZ12FSYbMDZB3KabqgWtlrri0t+snAS3fHobbOqz217otoZVZWdNSD2ey
dSjg==
X-Gm-Message-State: AHPjjUiBGLfytLbxKhNAXAB2JtSiCbzWRZnrGgPnJFr01FsaeqRT1Hx7
g5+HgdLVbpCYUGT+GSKsouYYx2DB45Fgk/ZrL5D6tw==
X-Google-Smtp-Source: AOwi7QDGZSeVm/af5de6/SldFVe805oZ4Sld1WF65kheJLdRry4TzNQHiGvagfEEDKEVfbemZ6vgjp8OjZn3Ai+3Kxw=
X-Received: by 10.28.7.83 with SMTP id 80mr2453331wmh.158.1505309075271; Wed,
13 Sep 2017 06:24:35 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.28.74.155 with HTTP; Wed, 13 Sep 2017 06:24:14 -0700 (PDT)
From: "Russell O'Connor" <roconnor@blockstream.io>
Date: Wed, 13 Sep 2017 09:24:14 -0400
Message-ID: <CAMZUoKkgr-5ziDL09jkC1wOVprcZ2=jcd-PhHnSn79hcVhrrTA@mail.gmail.com>
To: Mark Friedenbach <mark@friedenbach.org>,
Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary="001a11443776b58e4905591214a0"
X-Spam-Status: No, score=0.5 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
HTML_MESSAGE,RCVD_IN_DNSWL_NONE,RCVD_IN_SORBS_SPAM autolearn=disabled
version=3.3.1
X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on
smtp1.linux-foundation.org
Subject: [bitcoin-dev] SigOps limit.
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: Wed, 13 Sep 2017 13:24:37 -0000
--001a11443776b58e4905591214a0
Content-Type: text/plain; charset="UTF-8"
On Tue, Sep 12, 2017 at 3:57 PM, Mark Friedenbach via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> 4MB of secp256k1 signatures takes 10s to validate on my 5 year old
> laptop (125,000 signatures, ignoring public keys and other things that
> would consume space). That's much less than bad blocks that can be
> constructed using other vulnerabilities.
If there were no sigops limits, I believe the worst case block could have
closer to 1,000,000 CHECKSIG operations. Signature checks are cached so
while repeating the sequence "2DUP CHECKSIGVERIFY" does create a lot of
checksig operations, the cached values prevent a lot of work being done.
To defeat the cache one can repeat the sequence "2DUP CHECKSIG DROP
CODESEPARATOR", which will create unique signature validation requests
every 4 bytes.
--001a11443776b58e4905591214a0
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr">On Tue, Sep 12, 2017 at 3:57 PM, Mark Friedenbach via bitc=
oin-dev <span dir=3D"ltr"><<a href=3D"mailto:bitcoin-dev@lists.linuxfoun=
dation.org" target=3D"_blank">bitcoin-dev@lists.linuxfoundation.org</a>>=
</span> wrote:<br><div class=3D"gmail_extra"><div class=3D"gmail_quote"><bl=
ockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #=
ccc solid;padding-left:1ex"><span class=3D""><br>
</span>4MB of secp256k1 signatures takes 10s to validate on my 5 year old<b=
r>
laptop (125,000 signatures, ignoring public keys and other things that<br>
would consume space). That's much less than bad blocks that can be<br>
constructed using other vulnerabilities.</blockquote><div><br></div><div>If=
there were no sigops limits, I believe the worst case block could have clo=
ser to 1,000,000 CHECKSIG operations.=C2=A0 Signature checks are cached so =
while repeating the sequence "2DUP CHECKSIGVERIFY" does create a =
lot of checksig operations, the cached values prevent a lot of work being d=
one.</div><div><br></div><div>To defeat the cache one can repeat the sequen=
ce "2DUP CHECKSIG DROP CODESEPARATOR", which will create unique s=
ignature validation requests every 4 bytes.<br></div></div></div></div>
--001a11443776b58e4905591214a0--
|
