From: Jeff Garzik <jgarzik@bitpay•com>
To: Ron OHara <ron.ohara54@gmail•com>
Cc: Bitcoin Dev <bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] Time
Date: Thu, 24 Jul 2014 21:41:19 -0400 [thread overview]
Message-ID: <CAJHLa0NhXdhANCY6rk81VYqUR-fPxe8b27Py08OfuyrqHUB-Tg@mail.gmail.com> (raw)
In-Reply-To: <53D1AF6C.7010802@gmail.com>
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.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? 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
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>
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--
Jeff Garzik
Bitcoin core developer and open source evangelist
BitPay, Inc. https://bitpay.com/
next prev parent reply other threads:[~2014-07-25 2:36 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-25 1:14 Ron OHara
2014-07-25 1:41 ` Jeff Garzik [this message]
2014-07-25 2:35 ` Aaron Voisine
2014-07-25 2:39 ` Gregory Maxwell
2014-07-25 3:21 ` William Yager
2014-07-25 5:56 ` Aaron Voisine
2014-07-25 10:26 ` Mike Hearn
2014-07-25 14:45 ` Aaron Voisine
2014-07-25 16:03 ` Mike Hearn
2014-07-25 16:22 ` Natanael
2014-07-25 18:14 ` Aaron Voisine
2014-07-25 10:30 ` Mike Hearn
2014-07-27 22:22 ` Peter Todd
2014-07-28 17:33 ` Troy Benjegerdes
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