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: <ZmnSCPxj@protonmail.com>
Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136])
by lists.linuxfoundation.org (Postfix) with ESMTP id 651E2C013E
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 4 Mar 2020 23:29:21 +0000 (UTC)
Received: from localhost (localhost [127.0.0.1])
by silver.osuosl.org (Postfix) with ESMTP id 612E720387
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 4 Mar 2020 23:29:21 +0000 (UTC)
X-Virus-Scanned: amavisd-new at osuosl.org
Received: from silver.osuosl.org ([127.0.0.1])
by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024)
with ESMTP id JrNLu5iDniWv
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 4 Mar 2020 23:29:19 +0000 (UTC)
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6
Received: from mail-40130.protonmail.ch (mail-40130.protonmail.ch
[185.70.40.130])
by silver.osuosl.org (Postfix) with ESMTPS id 4B245200E5
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 4 Mar 2020 23:29:19 +0000 (UTC)
Date: Wed, 04 Mar 2020 23:29:09 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com;
s=default; t=1583364556;
bh=7VuNZcPzm9AeLJtUJsTswfGuczefb9BbpPO/zXCXTRI=;
h=Date:To:From:Reply-To:Subject:In-Reply-To:References:Feedback-ID:
From;
b=bT/lJ2AWqawvu9a6f27lnsXAzVIoUtkHNca+TrFvSnpCnLjuF42fuldYSYTbpXREv
q6VW1bHVMBcU5r41U34wrJniuRnPwVFrKNKmiH8IQcl/bTLSrPglmfqaXDctzvf/s9
WN34vKXswaCkQ4mglroElmXFr8Wh02il+ROwkums=
To: Lloyd Fournier <lloyd.fourn@gmail.com>,
Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Reply-To: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Message-ID: <tXbP-9UVzs4Je3MdjTYAbm0ZWVMctlhY15v6_G8CCRnaWJjo8VU8h2WDfUSiqnWl8rQa0zbrsupNRNtss0gDFjMiqwNil_ahiqSraICAP9Q=@protonmail.com>
In-Reply-To: <CAH5Bsr2m3+kN67h0Dd+60-i3WCnCRXr_ywzub5_OV=UxxzN3hQ@mail.gmail.com>
References: <CAH5Bsr2m3+kN67h0Dd+60-i3WCnCRXr_ywzub5_OV=UxxzN3hQ@mail.gmail.com>
Feedback-ID: el4j0RWPRERue64lIQeq9Y2FP-mdB86tFqjmrJyEPR9VAtMovPEo9tvgA0CrTsSHJeeyPXqnoAu6DN-R04uJUg==:Ext:ProtonMail
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Subject: Re: [bitcoin-dev] Hash function requirements for Taproot
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, 04 Mar 2020 23:29:21 -0000
Good morning LL,
Thank you very much for this work, it seems quite interesting.
> 5. You can completely circumvent this result by using coin-tossing rather=
than MuSig for the key generation protocol. In most cases this doesn't eve=
n add any extra rounds of communication since you are doing 3-round coin to=
ssing to choose the R values for the signatures that spend from the joint o=
utput anyway. You can just toss your public keys in parallel.
I am uncertain what you mean here by "coin-tossing".
From the comparison to MuSig, I imagine it is an interactive key generation=
protocol like this:
* Everybody generates fresh keypairs.
* Everybody sends the hash of their pubkey to everyone else.
* After receiving a hash of pubkey from everyone else, everybody sends thei=
r pubkey to everyone else.
* They add all their pubkeys to generate the aggregate key (and if using Ta=
proot, use it as the internal key).
Is that correct?
In any case, the comparison to MuSig signing appears to imply interactive k=
ey generation.
The advantage of MuSig is that it requires no interactivity for key generat=
ion of n-of-n (I am told it requires interactivity to generate k-of-n).
However, it can generally be pointed out that, before you put anything into=
an n-of-n, you would damn well sure want to have *some* assurance that you=
can get it out later.
So in general you would need coordination and interaction anyway to arrange=
getting into an n-of-n in the first place.
On the other hand, it would be best to have at least some minimum of privac=
y by always interacting over Tor and having a Tor .onion address, which has=
absolutely horrid latency because human beings cry when peeling onions.
So in general reducing the latency by reducing communication rounds is bett=
er in general.
Counter to this, assuming you use an n-of-n in an offchain protocol of some=
sort, the number of communication rounds to generate the aggregate key may=
be dwarfed by the total number of communication rounds to create signature=
s to update the offchain protocol.
Counter counter to this is that one plan for reducing communications rounds=
for creating signatures during offchain operation is to (haha) use a Tapro=
ot with an n-of-n internal key and a tapscript that has n `OP_CHECKSIG` ope=
rations, so that for normal operation you just toss individual signatures a=
t each other but at termination of the offchain protocol you can do the hea=
vy MuSig-style signing with the n-of-n aggregate key.
Regards,
ZmnSCPxj
|
