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
|
Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193]
helo=mx.sourceforge.net)
by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76)
(envelope-from <voisine@gmail.com>) id 1X8ZzY-0005cg-5J
for bitcoin-development@lists.sourceforge.net;
Sat, 19 Jul 2014 19:08:20 +0000
Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of gmail.com
designates 209.85.219.52 as permitted sender)
client-ip=209.85.219.52; envelope-from=voisine@gmail.com;
helo=mail-oa0-f52.google.com;
Received: from mail-oa0-f52.google.com ([209.85.219.52])
by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128)
(Exim 4.76) id 1X8ZzW-0003kD-RQ
for bitcoin-development@lists.sourceforge.net;
Sat, 19 Jul 2014 19:08:20 +0000
Received: by mail-oa0-f52.google.com with SMTP id o6so5293325oag.39
for <bitcoin-development@lists.sourceforge.net>;
Sat, 19 Jul 2014 12:08:13 -0700 (PDT)
MIME-Version: 1.0
X-Received: by 10.60.147.229 with SMTP id tn5mr10540769oeb.11.1405796893380;
Sat, 19 Jul 2014 12:08:13 -0700 (PDT)
Received: by 10.60.169.109 with HTTP; Sat, 19 Jul 2014 12:08:13 -0700 (PDT)
In-Reply-To: <CAAS2fgQGF2d98ciMKkE70bqy01mANPhDtamYroeHOZrfML7rMQ@mail.gmail.com>
References: <CAPg+sBiTURdRAZbyk3guF5YzAAQebo8yY_TuXHUKYDEdLjDUdQ@mail.gmail.com>
<CANEZrP3fA3gZ5u6yViBZpdTYxyFvZT=uOTDEnL797OueXf-16g@mail.gmail.com>
<CA+s+GJAd00ba7SzoUYeGvTOoHRiysXtYmx4Cnq8xQLXZx_VwyQ@mail.gmail.com>
<CACq0ZD6BmTB_jwE9L0_zrWgVckb=LFL61fow1kuTSnjurbsq9A@mail.gmail.com>
<CAAS2fgSwzx7M9NLjoOgfAgQT2cHmUWYD8hBmwHRRhgG9UgmmhA@mail.gmail.com>
<CACq0ZD4GwDZbEK4oE_BJxN-nDTb_4+hhDFZ0T7xGAi8v3G349A@mail.gmail.com>
<CAAS2fgQGF2d98ciMKkE70bqy01mANPhDtamYroeHOZrfML7rMQ@mail.gmail.com>
Date: Sat, 19 Jul 2014 12:08:13 -0700
Message-ID: <CACq0ZD73OsGjZgVnvW_vqabwpaXon3=XN30JVXTMimH1-JtWDA@mail.gmail.com>
From: Aaron Voisine <voisine@gmail.com>
To: Gregory Maxwell <gmaxwell@gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
X-Spam-Score: -1.6 (-)
X-Spam-Report: Spam Filtering performed by mx.sourceforge.net.
See http://spamassassin.org/tag/ for more details.
-1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for
sender-domain
0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider
(voisine[at]gmail.com)
-0.0 SPF_PASS SPF: sender matches SPF record
-0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from
author's domain
0.1 DKIM_SIGNED Message has a DKIM or DK signature,
not necessarily valid
-0.1 DKIM_VALID Message has at least one valid DKIM or DK signature
X-Headers-End: 1X8ZzW-0003kD-RQ
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Small update to BIP 62
X-BeenThere: bitcoin-development@lists.sourceforge.net
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: <bitcoin-development.lists.sourceforge.net>
List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=unsubscribe>
List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=bitcoin-development>
List-Post: <mailto:bitcoin-development@lists.sourceforge.net>
List-Help: <mailto:bitcoin-development-request@lists.sourceforge.net?subject=help>
List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=subscribe>
X-List-Received-Date: Sat, 19 Jul 2014 19:08:20 -0000
Thanks g.maxwell, your explanation of *why* you can't just generate k
in a way that the verifier can duplicate is really helpful. This also
servers as a great illustration why engineers should never try to
designing their own crypto protocols! I knew enough to know not try
that at least.
Aaron Voisine
breadwallet.com
On Fri, Jul 18, 2014 at 11:56 PM, Gregory Maxwell <gmaxwell@gmail.com> wrot=
e:
> On Fri, Jul 18, 2014 at 9:38 PM, Aaron Voisine <voisine@gmail.com> wrote:
>> Well, you could always create a transaction with a different signature
>> hash, say, by changing something trivial like nLockTime, or changing
>> the order of inputs or outputs. Is that what you're talking about? Or
>> is there some sophistry I'm ignorant of having to do with the elliptic
>> curve math in the signature itself?
>
> No, though thats true too. I was talking about the properties of the DSA =
nonce:
>
> An attacker is not obligated to follow your protocol unless you can
> prevent him. You can _say_ use derandomized DSA all you like, but he
> can just not do so, there is no (reasonable) way to prove you're using
> a particular nonce generation scheme without revealing the private key
> in the process. The verifier cannot know the nonce or he can trivially
> recover your private key thus he can't just repeat the computation
> (well, plus if you're using RFC6979 the computation includes the
> private key), so short of a very fancy ZKP (stuff at the forefront of
> cryptographic/computer science) or precommiting to a nonce per public
> key (e.g. single use public keys), you cannot control how a DSA nonce
> was generated in the verifier in a way that would prevent equivalent
> but not identical signatures.
>
> (I believe there was some P.O.S. altcoin that was vulnerable because
> of precisely the above too=E2=80=94 thinking specifying a deterministic s=
igner
> would prevent someone from grinding signatures to improve their mining
> odds... there are signature systems which are naturally
> randomness-free: most hash based signatures and pairing short
> signatures are two examples that come to mind... but not DSA, schnorr,
> or any of their derivatives).
|
