From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1XAVMP-000851-PD for bitcoin-development@lists.sourceforge.net; Fri, 25 Jul 2014 02:35:53 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.219.53 as permitted sender) client-ip=209.85.219.53; envelope-from=voisine@gmail.com; helo=mail-oa0-f53.google.com; Received: from mail-oa0-f53.google.com ([209.85.219.53]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1XAVMO-00086r-Aw for bitcoin-development@lists.sourceforge.net; Fri, 25 Jul 2014 02:35:53 +0000 Received: by mail-oa0-f53.google.com with SMTP id j17so4897141oag.12 for ; Thu, 24 Jul 2014 19:35:46 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.182.97.97 with SMTP id dz1mr18719227obb.13.1406255746748; Thu, 24 Jul 2014 19:35:46 -0700 (PDT) Received: by 10.60.98.204 with HTTP; Thu, 24 Jul 2014 19:35:46 -0700 (PDT) In-Reply-To: <53D1AF6C.7010802@gmail.com> References: <53D1AF6C.7010802@gmail.com> Date: Thu, 24 Jul 2014 19:35:46 -0700 Message-ID: From: Aaron Voisine To: Ron OHara Content-Type: multipart/alternative; boundary=047d7b2e43863f999f04fefb6e2f X-Spam-Score: -0.6 (/) 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 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 X-Headers-End: 1XAVMO-00086r-Aw 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: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 25 Jul 2014 02:35:53 -0000 --047d7b2e43863f999f04fefb6e2f Content-Type: text/plain; charset=UTF-8 The upcoming release of breadwallet uses the height of the blockchain to enforce timed pin code lockouts for preventing an attacker from quickly making multiple pin guesses. This prevents them changing the devices system time to get around the lockout period. Aaron On Thursday, July 24, 2014, Ron OHara wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > I thought I should shortcut my research by asking a direct question here. > > As I understand it, the blockchain actually provides an extra piece of > reliable data that is not being exploited by applications. > > Which data? The time. In this case 'the time' as agreed by >50% of > the participants, where those participants have a strong financial > incentive to keep that 'time' fairly accurate. (+/- about 10 minutes) > > Is this a reasonable understanding of 'time'? ... aka timestamps on the > block > > Ok... 'time' on the blockchain could be 'gamed' ... but with great > difficulty. An application presented with a fake blockchain can use > quite a few heuristics to test the 'validity' of the block chain. > It can review the usual cryptographic proofs, and check that difficulty > is growing/declining only in a realistic manner up to the most recent > block. Even use some arbitrary test like difficulty > 10,000,000,000 > ... on the presumption that any less means that the Bitcoin system has > failed massively from where it currently is and has become an unreliable > time source. > > Reliable 'time' has been impossible up until now - because you need to > trust the time source, and that can always be faked. Using the > blockchain as an approximate time source gives you a world wide > consensus without direct trust of any player. > > So if this presumption is correct, then we can now build time capsule > applications that can not be tricked into exposing their contents too > early by running them in a virtual environment with the wrong system time. > > Is this right? or did miss I something fundamental? > > Ron > > - -- > public identify: https://www.onename.io/ron_ohara > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v2.0.20 (GNU/Linux) > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iQEcBAEBAgAGBQJT0a9sAAoJEAla1VT1+xc2ONQH/0R09guSNNCxP36KziAjfcBc > JEhxMpIlqTTYEvNXaBmuPy4BN+IZQ9izgrW/cvlEJJNMmc5/VIBk83WZltmDwcKl > oo4MIdmp6vz984GWToyyLcLSEDT60UE9Hhe+U9RyF5J9kwbN8Uy4ozUHhFVP/0EL > q4O1V6ggPbHWgH4q8m8E9qWOlIFXCDgCjxpL8Ptxsk+UlBq2NWMiwTz6Tbc9KOB4 > hOffzXCZV+DkwjFZD2Rc4rHaxw1yLuYr7DzmzwZbhRQclv9tZt9hoVaAT+RQpE1k > X7pi+zVzeMMng0bzUv8t/G+gq0gaelyV41MJQRparEXhnuYkgU7rAPKIQEG8qpc= > =T5fw > -----END PGP SIGNATURE----- > > > > ------------------------------------------------------------------------------ > 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 --047d7b2e43863f999f04fefb6e2f Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable The upcoming release of breadwallet uses the height of the blockchain to en= force timed=C2=A0pin code lockouts for=C2=A0preventing an attacker from qui= ckly=C2=A0making multiple pin guesses. This prevents them changing the devi= ces system time to get around the lockout period.

Aaron

On Thursday, July 24, 2014, Ron OHara <ron.ohara54@gmail.com> wrote:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I thought I should shortcut my research by asking a direct question here.
As I understand it, the blockchain actually provides an extra piece of
reliable data that is not being exploited by applications.

Which data? =C2=A0The time. =C2=A0 In this case 'the time' as agree= d by >50% of
the participants, where those participants have a strong financial
incentive to keep that 'time' fairly accurate. (+/- about 10 minute= s)

Is this a reasonable understanding of 'time'? ... aka timestamps on= the
block

Ok... 'time' on the blockchain could be 'gamed' ... but wit= h great
difficulty. An application presented with a fake blockchain can use
quite a few heuristics to test the 'validity' of the block chain. It can review the usual cryptographic proofs, and check that difficulty
is growing/declining only in a realistic manner up to the most recent
block. Even use some arbitrary test like difficulty > 10,000,000,000
... on the presumption that any less means that the Bitcoin system has
failed massively from where it currently is and has become an unreliable time source.

Reliable 'time' has been impossible up until now - because you need= to
trust the time source, and that can always be faked. =C2=A0Using the
blockchain as an approximate time source gives you a world wide
consensus without direct trust of any player.

So if this presumption is correct, then we can now build time capsule
applications that can not be tricked into exposing their contents too
early by running them in a virtual environment with the wrong system time.<= br>
Is this right? or did miss I something fundamental?

Ron

- --
public identify: https://www.onename.io/ron_ohara
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---------------------------------------------------------------------------= ---
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Code Sight - the same software that powers the world's largest code
search on Ohloh, the Black Duck Open Hub! Try it now.
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--

Aaron Voisine
breadwallet.com
--047d7b2e43863f999f04fefb6e2f--