summaryrefslogtreecommitdiff
path: root/22/e2f8a657fc2eac438f85f773cc06f2743cdaee
blob: c1652663d2db3f8257df083d24f4385394075dec (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
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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191]
	helo=mx.sourceforge.net)
	by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76)
	(envelope-from <natanael.l@gmail.com>) id 1XAiGm-0002YZ-Kg
	for bitcoin-development@lists.sourceforge.net;
	Fri, 25 Jul 2014 16:22:56 +0000
Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of gmail.com
	designates 209.85.212.177 as permitted sender)
	client-ip=209.85.212.177; envelope-from=natanael.l@gmail.com;
	helo=mail-wi0-f177.google.com; 
Received: from mail-wi0-f177.google.com ([209.85.212.177])
	by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128)
	(Exim 4.76) id 1XAiGk-0000SL-Iw
	for bitcoin-development@lists.sourceforge.net;
	Fri, 25 Jul 2014 16:22:56 +0000
Received: by mail-wi0-f177.google.com with SMTP id ho1so1272330wib.16
	for <bitcoin-development@lists.sourceforge.net>;
	Fri, 25 Jul 2014 09:22:47 -0700 (PDT)
MIME-Version: 1.0
X-Received: by 10.180.80.70 with SMTP id p6mr6834366wix.22.1406305366319; Fri,
	25 Jul 2014 09:22:46 -0700 (PDT)
Received: by 10.194.24.132 with HTTP; Fri, 25 Jul 2014 09:22:46 -0700 (PDT)
Received: by 10.194.24.132 with HTTP; Fri, 25 Jul 2014 09:22:46 -0700 (PDT)
In-Reply-To: <CANEZrP1wd7VirEisbgU7SJakSfnxmqbydfjab6Abz2-WKS90Ag@mail.gmail.com>
References: <53D1AF6C.7010802@gmail.com>
	<CACq0ZD56NuADphK-28zxR=dAPnZOPY4C0GO=zLdOhVxBpRKwoA@mail.gmail.com>
	<CAAS2fgSncktfkq0J23O04BWhtUD7V7OHCKAyuPbg7gJTKz-rTQ@mail.gmail.com>
	<CAG8oi1MNot6RruCu5cLSFAND5noZToPLvTqMP26bwKQGU_2C3g@mail.gmail.com>
	<CACq0ZD4nCJ+dzUG+KV+eCxE2My+T4Acr4qy-Y6A-dFvuRG=Eaw@mail.gmail.com>
	<CANEZrP0pMA=LB=Mi9xj9YbJ83=0r6Xa4_6Ua+wpAtsg5OdS7Kw@mail.gmail.com>
	<CACq0ZD7G1mKGW6ktraOhS7PuaJe_BRZzHpk0RsRmvwiPrpp_nA@mail.gmail.com>
	<CANEZrP1wd7VirEisbgU7SJakSfnxmqbydfjab6Abz2-WKS90Ag@mail.gmail.com>
Date: Fri, 25 Jul 2014 18:22:46 +0200
Message-ID: <CAAt2M18RTON97fS8yJR-NVOCH9Z_ZdDf1hVsFU-7EFv5ke9cYQ@mail.gmail.com>
From: Natanael <natanael.l@gmail.com>
To: Mike Hearn <mike@plan99.net>
Content-Type: multipart/alternative; boundary=f46d04428358ce2dd804ff06fbdc
X-Spam-Score: 0.4 (/)
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
	(natanael.l[at]gmail.com)
	-0.0 SPF_PASS               SPF: sender matches SPF record
	1.0 HTML_MESSAGE           BODY: HTML included in message
	-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
	1.0 FREEMAIL_REPLY         From and body contain different freemails
X-Headers-End: 1XAiGk-0000SL-Iw
Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] Time
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: Fri, 25 Jul 2014 16:22:56 -0000

--f46d04428358ce2dd804ff06fbdc
Content-Type: text/plain; charset=UTF-8

Probably because the network isn't designed for interactive proofs. Most
interactive algoritms AFAICT requires that some machine holds a secret
state (or at least continuous and untampered state, but you still need to
verify you're falling to the right machine), otherwise the machine can be
mimicked and "rewound" to earlier states. Without a challenge-response that
can't be faked, you've got problems.

There's no trusted machines here that you can rely on. The certainty of
having the right blockchain is a statistical one over longer periods of
time, not enough for a PIN you want verified right now. So you can always
be shown an old copy, and if your node isn't up to date yet then it can
also be shown fake chains further into the future.

Maybe you could throw in some kind of Secure Multiparty Computation among
the miners to enable challenge-response, with state saved in the blockchain
(so it can't be rolled back), but that would be fragile. How do you select
what nodes may participate? How do you prevent the secret state from
leaking? And performance would be absolutely horrible, and reliability is a
huge problem.
Den 25 jul 2014 18:03 skrev "Mike Hearn" <mike@plan99.net>:

> Sorry, you're right. I'd have hoped a delay that doubles on failure each
> time up to some max would be good enough, relying on the p2p network to
> unlock a PIN feels weird, but I can't really quantify why or what's wrong
> with it so I guess it's just me :-)
>
>
> On Fri, Jul 25, 2014 at 4:45 PM, Aaron Voisine <voisine@gmail.com> wrote:
>
>> The problem is if someone moves system time forward between app launches.
>> The lockout period doesn't have to be all that precise, it just makes you
>> wait for the next block, then 5, then 25, and so on. Using a well
>> known time server over https would also be a good option, but the wallet
>> app already has the chain height anyway.
>>
>>
>> On Friday, July 25, 2014, Mike Hearn <mike@plan99.net> wrote:
>>
>>>  Given that the speed at which the block chain advances is kind of
>>> unpredictable, I'd think it might be better to just record the time to disk
>>> when a PIN attempt is made and if you observe time going backwards, refuse
>>> to allow more attempts until it's advanced past the previous attempt.
>>>
>>>
>>> On Fri, Jul 25, 2014 at 7:56 AM, Aaron Voisine <voisine@gmail.com>
>>> wrote:
>>>
>>>> It's based on the block height, not the block's timestamp. If you have
>>>> access to the device and the phone itself is not pin locked, then you
>>>> can jailbreak it and get access to the wallet seed that way. A pin
>>>> locked device however is reasonably secure as the filesystem is
>>>> hardware aes encrypted to a combination of pin+uuid. This was just an
>>>> easy way to prevent multiple pin guesses by changing system time in
>>>> settings, so that isn't the weakest part of the security model.
>>>>
>>>> Aaron Voisine
>>>> breadwallet.com
>>>>
>>>>
>>>> On Thu, Jul 24, 2014 at 8:21 PM, William Yager <will.yager@gmail.com>
>>>> wrote:
>>>> > On Thu, Jul 24, 2014 at 10:39 PM, Gregory Maxwell <gmaxwell@gmail.com
>>>> >
>>>> > wrote:
>>>> >>
>>>> >>
>>>> >> Is breadwallet tamper resistant & zero on tamper hardware? otherwise
>>>> >> this sounds like security theater.... I attach a debugger to the
>>>> >> process (or modify the program) and ignore the block sourced time.
>>>> >>
>>>> >
>>>> > It's an iOS application. I would imagine it is substantially more
>>>> difficult
>>>> > to attach to a process (which, at the very least, requires root, and
>>>> perhaps
>>>> > other things on iOS) than to convince the device to change its system
>>>> time.
>>>> >
>>>> > That said, the security benefits might not be too substantial.
>>>> >
>>>> >
>>>> ------------------------------------------------------------------------------
>>>> > Want fast and easy access to all the code in your enterprise? Index
>>>> and
>>>> > search up to 200,000 lines of code with a free copy of Black Duck
>>>> > Code Sight - the same software that powers the world's largest code
>>>> > search on Ohloh, the Black Duck Open Hub! Try it now.
>>>> > http://p.sf.net/sfu/bds
>>>> > _______________________________________________
>>>> > Bitcoin-development mailing list
>>>> > Bitcoin-development@lists.sourceforge.net
>>>> > https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>>>> >
>>>>
>>>>
>>>> ------------------------------------------------------------------------------
>>>> Want fast and easy access to all the code in your enterprise? Index and
>>>> search up to 200,000 lines of code with a free copy of Black Duck
>>>> Code Sight - the same software that powers the world's largest code
>>>> search on Ohloh, the Black Duck Open Hub! Try it now.
>>>> http://p.sf.net/sfu/bds
>>>> _______________________________________________
>>>> Bitcoin-development mailing list
>>>> Bitcoin-development@lists.sourceforge.net
>>>> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>>>>
>>>
>>>
>>
>> --
>>
>> Aaron Voisine
>> breadwallet.com
>>
>
>
>
> ------------------------------------------------------------------------------
> Want fast and easy access to all the code in your enterprise? Index and
> search up to 200,000 lines of code with a free copy of Black Duck
> Code Sight - the same software that powers the world's largest code
> search on Ohloh, the Black Duck Open Hub! Try it now.
> http://p.sf.net/sfu/bds
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
>

--f46d04428358ce2dd804ff06fbdc
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<p dir=3D"ltr">Probably because the network isn&#39;t designed for interact=
ive proofs. Most interactive algoritms AFAICT requires that some machine ho=
lds a secret state (or at least continuous and untampered state, but you st=
ill need to verify you&#39;re falling to the right machine), otherwise the =
machine can be mimicked and &quot;rewound&quot; to earlier states. Without =
a challenge-response that can&#39;t be faked, you&#39;ve got problems. </p>

<p dir=3D"ltr">There&#39;s no trusted machines here that you can rely on. T=
he certainty of having the right blockchain is a statistical one over longe=
r periods of time, not enough for a PIN you want verified right now. So you=
 can always be shown an old copy, and if your node isn&#39;t up to date yet=
 then it can also be shown fake chains further into the future. </p>

<p dir=3D"ltr">Maybe you could throw in some kind of Secure Multiparty Comp=
utation among the miners to enable challenge-response, with state saved in =
the blockchain (so it can&#39;t be rolled back), but that would be fragile.=
 How do you select what nodes may participate? How do you prevent the secre=
t state from leaking? And performance would be absolutely horrible, and rel=
iability is a huge problem. </p>

<div class=3D"gmail_quote">Den 25 jul 2014 18:03 skrev &quot;Mike Hearn&quo=
t; &lt;<a href=3D"mailto:mike@plan99.net">mike@plan99.net</a>&gt;:<br type=
=3D"attribution"><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8=
ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir=3D"ltr">Sorry, you&#39;re right. I&#39;d have hoped a delay that d=
oubles on failure each time up to some max would be good enough, relying on=
 the p2p network to unlock a PIN feels weird, but I can&#39;t really quanti=
fy why or what&#39;s wrong with it so I guess it&#39;s just me :-)</div>

<div class=3D"gmail_extra"><br><br><div class=3D"gmail_quote">On Fri, Jul 2=
5, 2014 at 4:45 PM, Aaron Voisine <span dir=3D"ltr">&lt;<a href=3D"mailto:v=
oisine@gmail.com" target=3D"_blank">voisine@gmail.com</a>&gt;</span> wrote:=
<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-lef=
t:1px #ccc solid;padding-left:1ex">

The problem is if someone moves system time forward between app launches. T=
he lockout period doesn&#39;t have to be all that precise, it just makes yo=
u wait for the next block, then 5, then 25, and so on. Using a well known=
=C2=A0time server over<span></span>=C2=A0https would also be a good option,=
 but the wallet app already has the chain height anyway.<div>

<div><br>
<br>On Friday, July 25, 2014, Mike Hearn &lt;<a href=3D"mailto:mike@plan99.=
net" target=3D"_blank">mike@plan99.net</a>&gt; wrote:<br><blockquote class=
=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padd=
ing-left:1ex">

<div dir=3D"ltr">
Given that the speed at which the block chain advances is kind of unpredict=
able, I&#39;d think it might be better to just record the time to disk when=
 a PIN attempt is made and if you observe time going backwards, refuse to a=
llow more attempts until it&#39;s advanced past the previous attempt.</div>



<div class=3D"gmail_extra"><br><br><div class=3D"gmail_quote">On Fri, Jul 2=
5, 2014 at 7:56 AM, Aaron Voisine <span dir=3D"ltr">&lt;<a>voisine@gmail.co=
m</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">
It&#39;s based on the block height, not the block&#39;s timestamp. If you h=
ave<br>
access to the device and the phone itself is not pin locked, then you<br>
can jailbreak it and get access to the wallet seed that way. A pin<br>
locked device however is reasonably secure as the filesystem is<br>
hardware aes encrypted to a combination of pin+uuid. This was just an<br>
easy way to prevent multiple pin guesses by changing system time in<br>
settings, so that isn&#39;t the weakest part of the security model.<br>
<span><font color=3D"#888888"><br>
Aaron Voisine<br>
<a href=3D"http://breadwallet.com" target=3D"_blank">breadwallet.com</a><br=
>
</font></span><div><div><br>
<br>
On Thu, Jul 24, 2014 at 8:21 PM, William Yager &lt;<a>will.yager@gmail.com<=
/a>&gt; wrote:<br>
&gt; On Thu, Jul 24, 2014 at 10:39 PM, Gregory Maxwell &lt;<a>gmaxwell@gmai=
l.com</a>&gt;<br>
&gt; wrote:<br>
&gt;&gt;<br>
&gt;&gt;<br>
&gt;&gt; Is breadwallet tamper resistant &amp; zero on tamper hardware? oth=
erwise<br>
&gt;&gt; this sounds like security theater.... I attach a debugger to the<b=
r>
&gt;&gt; process (or modify the program) and ignore the block sourced time.=
<br>
&gt;&gt;<br>
&gt;<br>
&gt; It&#39;s an iOS application. I would imagine it is substantially more =
difficult<br>
&gt; to attach to a process (which, at the very least, requires root, and p=
erhaps<br>
&gt; other things on iOS) than to convince the device to change its system =
time.<br>
&gt;<br>
&gt; That said, the security benefits might not be too substantial.<br>
&gt;<br>
</div></div><div><div>&gt; ------------------------------------------------=
------------------------------<br>
&gt; Want fast and easy access to all the code in your enterprise? Index an=
d<br>
&gt; search up to 200,000 lines of code with a free copy of Black Duck<br>
&gt; Code Sight - the same software that powers the world&#39;s largest cod=
e<br>
&gt; search on Ohloh, the Black Duck Open Hub! Try it now.<br>
&gt; <a href=3D"http://p.sf.net/sfu/bds" target=3D"_blank">http://p.sf.net/=
sfu/bds</a><br>
&gt; _______________________________________________<br>
&gt; Bitcoin-development mailing list<br>
&gt; <a>Bitcoin-development@lists.sourceforge.net</a><br>
&gt; <a href=3D"https://lists.sourceforge.net/lists/listinfo/bitcoin-develo=
pment" target=3D"_blank">https://lists.sourceforge.net/lists/listinfo/bitco=
in-development</a><br>
&gt;<br>
<br>
---------------------------------------------------------------------------=
---<br>
Want fast and easy access to all the code in your enterprise? Index and<br>
search up to 200,000 lines of code with a free copy of Black Duck<br>
Code Sight - the same software that powers the world&#39;s largest code<br>
search on Ohloh, the Black Duck Open Hub! Try it now.<br>
<a href=3D"http://p.sf.net/sfu/bds" target=3D"_blank">http://p.sf.net/sfu/b=
ds</a><br>
_______________________________________________<br>
Bitcoin-development mailing list<br>
<a>Bitcoin-development@lists.sourceforge.net</a><br>
<a href=3D"https://lists.sourceforge.net/lists/listinfo/bitcoin-development=
" target=3D"_blank">https://lists.sourceforge.net/lists/listinfo/bitcoin-de=
velopment</a><br>
</div></div></blockquote></div><br></div>
</blockquote><br><br></div></div><span><font color=3D"#888888">-- <br><br>A=
aron Voisine<br><a href=3D"http://breadwallet.com" target=3D"_blank">breadw=
allet.com</a><br>
</font></span></blockquote></div><br></div>
<br>-----------------------------------------------------------------------=
-------<br>
Want fast and easy access to all the code in your enterprise? Index and<br>
search up to 200,000 lines of code with a free copy of Black Duck<br>
Code Sight - the same software that powers the world&#39;s largest code<br>
search on Ohloh, the Black Duck Open Hub! Try it now.<br>
<a href=3D"http://p.sf.net/sfu/bds" target=3D"_blank">http://p.sf.net/sfu/b=
ds</a><br>_______________________________________________<br>
Bitcoin-development mailing list<br>
<a href=3D"mailto:Bitcoin-development@lists.sourceforge.net">Bitcoin-develo=
pment@lists.sourceforge.net</a><br>
<a href=3D"https://lists.sourceforge.net/lists/listinfo/bitcoin-development=
" target=3D"_blank">https://lists.sourceforge.net/lists/listinfo/bitcoin-de=
velopment</a><br>
<br></blockquote></div>

--f46d04428358ce2dd804ff06fbdc--