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 <ron.ohar...@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? 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/ ------------------------------------------------------------------------------ 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
