summaryrefslogtreecommitdiff
path: root/1e/07ea9589875c4ba22c453e5a89d401e5540fae
blob: ceee96b7c4d64acb38822e0795af19e9e693c527 (plain)
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: <kanzure@gmail.com>
Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org
	[172.17.192.35])
	by mail.linuxfoundation.org (Postfix) with ESMTPS id 44ABBE36
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Wed,  7 Aug 2019 20:34:42 +0000 (UTC)
X-Greylist: whitelisted by SQLgrey-1.7.6
Received: from mail-ua1-f54.google.com (mail-ua1-f54.google.com
	[209.85.222.54])
	by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 2407A7D2
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Wed,  7 Aug 2019 20:34:41 +0000 (UTC)
Received: by mail-ua1-f54.google.com with SMTP id a97so35495103uaa.9
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Wed, 07 Aug 2019 13:34:41 -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=lBWYg3+3KF2AmQLXF1O9+19tyeyJkeu1JlOGUTYnb0w=;
	b=E2rjFxvjAb+JaFa9GCYXHcybV0GwFOBNmkTQxCJSFMNTUdnpSW0TuDIrkXnnRDX28N
	Pw5EM9eACB34+cgiWX1OYaXmAyMoWut185NcTR68M7g6T3eWiMWAx0k5ax7WPry2lvwq
	FXZICVKks2YSgWj1Br38NUE+dFViau2MtNH2wly+fOQ9eXGSzcDg3of7NwjkUlH37Y2S
	gxvOJBAELQusGH7FRnpns+3vLwMRtfcxdjiQJOwHSE7ymOBCuDC3vAOpmY/plujuuGc1
	uhyeE/YLW/zyog0DkHyTB5GKVG+zAuyh5dvHYraBanvFS5Ezz9X03PBPLGO+9lXAkO/p
	ETJA==
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=lBWYg3+3KF2AmQLXF1O9+19tyeyJkeu1JlOGUTYnb0w=;
	b=FYX3zde2Y54zG6GEYGw5lMbTPvHV8VqtvA9zyB27b7HwI53WACllWmKW7yNYRwTaxV
	VShzC4w4DJ11Rm41SEbAnwAZqnwTFZS06HiYBxKK35wjxkkL/S1mPtzXp5fIN+x0xRp8
	SEn9STBpLf+cgWMZRJpBVDRhhKy/8nG1r9SXgqiGCgSkiweVs/rPdsfKcVR/uGDNcZcD
	Eb95ANQCuldq64pmsRzgUSHloriiw1x/Bpc/jvVsyGNLnwrsrb4ypO9fDPTzFHC09IPS
	1lhz6fCofoZPM0UNgieTkKHgk7XVuUa4yjEAaRRbKzuinsZFU7mwgiegfwWoXiKqvRoe
	ps7A==
X-Gm-Message-State: APjAAAXBFjKPeYWkOaDFQYw7D1wBLff/GYyVt1/yFH1hQJOY6iV75aGT
	aYu7Ak2C03DwJi8a8gekB7xyZNf5gTnERiXFjr+etrqV
X-Google-Smtp-Source: APXvYqzxcYD8np57cJROTyLT4g+85W7zEPC2hpV971PQHIyp8YiSL/GKriqr/IRXUvmzZQURKi38yynlPE5C2sskfH8=
X-Received: by 2002:ab0:70d9:: with SMTP id r25mr6490357ual.109.1565210079688; 
	Wed, 07 Aug 2019 13:34:39 -0700 (PDT)
MIME-Version: 1.0
References: <CABaSBawe_oF_zoso2RQBX+7OWDoCwC7T2MeKSX9fYRUQaY_xmg@mail.gmail.com>
In-Reply-To: <CABaSBawe_oF_zoso2RQBX+7OWDoCwC7T2MeKSX9fYRUQaY_xmg@mail.gmail.com>
From: Bryan Bishop <kanzure@gmail.com>
Date: Wed, 7 Aug 2019 15:32:47 -0500
Message-ID: <CABaSBawQhC5EDbyc8c0rk1JxjF2NJBn+mb6tPgvTwkNXOPcSGg@mail.gmail.com>
To: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>,
	Bryan Bishop <kanzure@gmail.com>
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] Bitcoin vaults with anti-theft recovery/clawback
	mechanisms
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, 07 Aug 2019 20:34:42 -0000

Hi,

One of the biggest problems with the vault scheme (besides all of the
setup data that has to be stored for a long time) is an attacker that
silently steals the hot wallet private key and waits for the vault's
owner to make a delayed-spend transaction to initiate a withdrawal
from the vault. If the user was unaware of the theft of the key, then
the attacker could steal the funds after the delay period.

To mitigate this, it is important to choose a stipend or withdrawal
amount per withdrawal period like x% of the funds. This limits the
total stolen funds to x% because once the funds are stolen the user
would know their hot key is compromised, and the user would know to
instead use one of the other clawback paths during all of the future
withdrawal delay periods instead of letting the delay timeout all the
way to the (stolen) default/hot key.

The reason why a loss limiter is the way to go is because there's
currently no way (that I am aware of, without an upgrade) to force an
attacker to reveal his key on the blockchain while also forcing the
attacker to use a timelock before the key can spend the coins. I am
curious about what the smallest least invasive soft-fork would be for
enabling this kind of timelock. There are so many covenant proposals
at this point (CHECKSIGFROMSTACK, SECURETHEBAG, CHECKOUTPUTVERIFY,
....). Or there's crazy things like a fork that enables a transaction
mode where the (timelock...) script of the first output is
automatically prefixed to any of the other scripts on any of the other
outputs when an input tries to spend in the future. A thief could add
his key to a new output on the transaction and try to spend (just like
a user would with a fresh/rotated key), but the OP_CSV would be
automatically added to his script to implement the public observation
delay window.

Also, there was other previous work that I was only informed about
today after posting my proposal, so I should mention these as related
work:
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2018-February/015793.html
https://blog.oleganza.com/post/163955782228/how-segwit-makes-security-better
https://www.youtube.com/watch?v=diNxp3ZTquo
https://bitcointalk.org/index.php?topic=5111656

- Bryan
http://heybryan.org/