From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1XAVMy-0007Ly-Vb for bitcoin-development@lists.sourceforge.net; Fri, 25 Jul 2014 02:36:29 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of bitpay.com designates 209.85.213.172 as permitted sender) client-ip=209.85.213.172; envelope-from=jgarzik@bitpay.com; helo=mail-ig0-f172.google.com; Received: from mail-ig0-f172.google.com ([209.85.213.172]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1XAVMx-0006cC-Qs for bitcoin-development@lists.sourceforge.net; Fri, 25 Jul 2014 02:36:28 +0000 Received: by mail-ig0-f172.google.com with SMTP id h15so234825igd.5 for ; Thu, 24 Jul 2014 19:36:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-type; bh=0LAaf7q4vAVSFfgEXYb5DyzZx0tMPmj72CkMFFk3Tag=; b=BulF1YDNptuia4DI92VSp390YFWC8jjjWTR5GJi/qRHFFe1udEkdfthBnxVMXqu5su bl7I+E5BFaXNiwaSpK4Qg58cy2PC9eQ+bg+Z8SRp+q5X2jLdHt83xZHdxVgdIrUuXSIq h56G7y5WBX/F0qEb1iM2IHDBVMiiLxUIbFSCW4eLFX7PU+rCoT0PF6crzHuObxCVKn9w 349u41UsIxz46+dHJJPokPxBtd69GEp7+57XJZTnUZUt0WS35GpAtYPKhtjbaKXrBsjP MGjlf24Pv6ZEW+FmLOeziodXktlZQqCbt+Dv+4xmkUu4xfHVa1VnCTbmw0cqsbY+jIJc y66A== X-Gm-Message-State: ALoCoQng9Al02oKowefguL+bNjxi6g8uIyajThtYsPpUNsXIpkjZIu1k83TMFZIdJnY+ki55n0WW X-Received: by 10.50.107.7 with SMTP id gy7mr1070666igb.15.1406252499420; Thu, 24 Jul 2014 18:41:39 -0700 (PDT) MIME-Version: 1.0 Received: by 10.107.10.78 with HTTP; Thu, 24 Jul 2014 18:41:19 -0700 (PDT) In-Reply-To: <53D1AF6C.7010802@gmail.com> References: <53D1AF6C.7010802@gmail.com> From: Jeff Garzik Date: Thu, 24 Jul 2014 21:41:19 -0400 Message-ID: To: Ron OHara Content-Type: text/plain; charset=UTF-8 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 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: 1XAVMx-0006cC-Qs Cc: Bitcoin Dev 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 02:36:29 -0000 Miners are free to set the block's timestamp to whatever they please, within a certain +/- time window. Time might even go backwards a tiny bit from the last block to the next block. On Thu, Jul 24, 2014 at 9:14 PM, 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 -- Jeff Garzik Bitcoin core developer and open source evangelist BitPay, Inc. https://bitpay.com/