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From: Gavin Andresen <gavinandresen@gmail.com>
To: kjj <kjj@jerviss.org>
Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] Difficulty adjustment / time issues
Date: Wed, 14 Sep 2011 10:45:36 -0400	[thread overview]
Message-ID: <CABsx9T0JvnOaBy+irHtnN1zMWP8FiDTn=kn-01ky+V2MW1suTg@mail.gmail.com> (raw)
In-Reply-To: <4E6F83C3.9020108@jerviss.org>

> But that doesn't solve the whole problem, because the block timestamp
> checking is based on the assumption that the node is looking at the bitcoin
> clock rather than the, ahem, real clock.  If we change the idea of network
> time to NTP, we will then need to write (and test!) new block timestamp
> rules to account for the new assumptions.

Why?

The block timestamp rules currently give HOURS of wiggle-room for
timestamps. We can't change those rules without risking a chain split.

Here's a thumbnail sketch of what I'm thinking:

When new tip-of-chain blocks are received, IF their timestamp is
unreasonable with respect to system time and the previous block's
timestamp, then add them to a 'discouraged' list.  (but follow the
current rules for outright rejecting blocks based on timestamps too
far in the future or past)

Modify the getwork code to build on the second-from-tip block if the
first-on-tip block is on the discouraged list.

Assuming a majority of pools/miners adopt the "discourage blocks with
stale timestamps" rule, that should squash any incentive for cartels
to try to start playing with difficulty-- you would have to have 50+%
power to start, or you risk producing mostly orphan blocks.

> Also, this is going to cause problems for at least one pool operator.

I'll trade more security for "make at least one pool operator have to
do some work" any day.

-- 
--
Gavin Andresen



  reply	other threads:[~2011-09-14 14:45 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-13 15:06 [Bitcoin-development] Difficulty adjustment / time issues Gavin Andresen
2011-09-13 15:15 ` Vladimir Marchenko
2011-09-13 15:54 ` John Smith
2011-09-13 16:24 ` kjj
2011-09-14 14:45   ` Gavin Andresen [this message]
2011-09-14 15:43     ` Luke-Jr
2011-09-14 16:06       ` Christian Decker
2011-09-14 19:52     ` Aidan Thornton
2011-09-14 20:09       ` Gregory Maxwell
2011-09-14 20:28         ` Gavin Andresen
2011-09-14 21:36           ` Alex Waters
2011-09-14 21:51             ` Gregory Maxwell
2011-09-14 22:07               ` theymos
2011-09-14 23:01         ` Luke-Jr
2011-09-13 16:48 ` Luke-Jr
2011-09-14 21:45 ` theymos
2011-11-07 15:02 ` Pieter Wuille
2011-11-07 15:27   ` Luke-Jr
2011-11-07 15:43     ` Pieter Wuille

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