From: "Jorge Timón" <timon.elviejo@gmail•com>
To: Andy Parkins <andyparkins@gmail•com>
Cc: bitcoin-development@lists•sourceforge.net
Subject: Re: [Bitcoin-development] Addressing rapid changes in mining power
Date: Wed, 23 Nov 2011 16:38:30 +0100 [thread overview]
Message-ID: <CAGQP0AGWTa-iRsryMZnFxnMEPRdy_hm+P+FUN9jBVK0F+AgVDA@mail.gmail.com> (raw)
In-Reply-To: <201111231529.46154.andyparkins@gmail.com>
But the protocol must have a deterministic way to determine if a block
must be accepted or rejected.
I don't know what NTP is, but if you can have a perfect distributed
clock your proposal may work.
2011/11/23, Andy Parkins <andyparkins@gmail•com>:
> On 2011 November 23 Wednesday, Jorge Timón wrote:
>
>> Well, I meant "the probability of your block being the hardest".
>> What a miner can do is hash the block (cheating the timestamp) for 2
>> more minutes than the rest of the people and then send it to the other
>> nodes. Nodes cannot possibly know when did you hashed the block only
>> by looking at their clock when they receive it, because there's also
>> network latency.
>
> True enough; but then the same is true for everyone else. If the window is
> 2
> minutes after the stated time, then everyone _can_ wait until the end of
> that
> window. However, they risk their block being rejected by their peers, and
> their efforts are wasted. In fact, it can be guaranteed by making the
> accept
> window zero. There is then no reason to carry on computing after the reward
> window closes, since you know your peers will reject it.
>
>> > (2) For the network clock; see util.cpp:GetAdjustedTime().
>>
>> 1) This is part of the satoshi client but not the protocol. A miner
>> can rewrite this part of the code and there won't be anything in the
>> chain that contradicts the protocol.
>
> Well yes. What does that matter? It's only a way of calculating an average
> time. The node can use any clock it wants, as long as the block time is
> verified by the peers.
>
>> 2) I haven't read the code but I'm pretty sure that's not a perfect
>> decentralized clock.
>
> It definitely isn't. NTP is mentioned in the source as an alternative.
>
>> I will be more specific. Where's the network clock in the chain (in
>> the protocol)?
>
> It's nothing to do with the protocol; it's an individual miner choosing
> whether to accept or reject a block based on the timestamp it claims, and
> the
> current time as the miner sees it. For the sake of compatibility, the
> clients
> currently choose to use a community clock as "current", as established from
> the time they receive from peers in the "version" message (it actually holds
> offsets between them, which is pretty bad, as a long-connected client will
> drift). They don't have to, but if miners aren't using time that
> approximates
> what their peers are using, under my system, their blocks would be rejected:
> so an incentive to use that "community clock" exists.
>
>
>
> Andy
>
> --
> Dr Andy Parkins
> andyparkins@gmail•com
>
--
Jorge Timón
prev parent reply other threads:[~2011-11-23 15:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-23 10:35 Andy Parkins
2011-11-23 11:25 ` Jorge Timón
2011-11-23 11:30 ` Andy Parkins
2011-11-23 11:51 ` Jorge Timón
2011-11-23 12:10 ` Christian Decker
2011-11-23 13:13 ` Andy Parkins
2011-11-23 14:38 ` Christian Decker
2011-11-23 15:09 ` Gavin Andresen
2011-11-23 15:35 ` Alan Reiner
2011-11-23 15:39 ` Andy Parkins
2011-11-23 16:26 ` Joel Joonatan Kaartinen
2011-11-23 15:11 ` Andy Parkins
2011-11-23 12:54 ` Andy Parkins
2011-11-23 15:10 ` Jorge Timón
2011-11-23 15:29 ` Andy Parkins
2011-11-23 15:38 ` Jorge Timón [this message]
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