From: Mark Friedenbach <mark@monetize•io>
To: bitcoin-development@lists•sourceforge.net
Subject: Re: [Bitcoin-development] Committing to extra block data/a better merge-mine standard
Date: Mon, 04 Nov 2013 11:53:05 -0800 [thread overview]
Message-ID: <5277FB21.3050306@monetize.io> (raw)
In-Reply-To: <CANEZrP18Tz6OwOE7jeS3-Z2m=HuQiue+ZwRzS01mpqbCoPteZQ@mail.gmail.com>
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On 11/4/13 11:38 AM, Mike Hearn wrote:
> The Merkle branch doesn't get stored indefinitely though, whereas
> the coinbase hash does. The data stored in the coinbase [output]
> can always just be the 256-bit root hash truncated to less.
>
> I doubt the additional bytes make much difference really, so the
> additional complexity may not be worth it. But it wouldn't be an
> issue to do.
The bits make a difference if you are merged mining. You can use the
birthday attack to construct two data trees whose hash match the
(truncated) value, each containing separate aux block headers. This
allows you to double-count the bitcoin PoW for more than one aux block
on the same chain, potentially facilitating aux chain attacks.
If you want 128 bits of security for merged mined aux chains, you need
256 bits of hash in the coinbase.
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next prev parent reply other threads:[~2013-11-04 19:53 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-04 11:26 [Bitcoin-development] Auto-generated miner backbone Mike Hearn
2013-11-04 11:53 ` Peter Todd
2013-11-04 12:00 ` Mike Hearn
2013-11-04 18:16 ` [Bitcoin-development] Committing to extra block data/a better merge-mine standard Peter Todd
2013-11-04 18:32 ` Peter Todd
2013-11-04 19:11 ` Mark Friedenbach
2013-11-15 22:06 ` Peter Todd
2013-11-04 19:38 ` Mike Hearn
2013-11-04 19:53 ` Mark Friedenbach [this message]
2013-11-04 20:10 ` Mike Hearn
2013-11-04 11:58 ` [Bitcoin-development] Auto-generated miner backbone Michael Gronager
2013-11-04 12:03 ` Mike Hearn
2013-11-04 12:20 ` Peter Todd
2013-11-04 12:40 ` Michael Gronager
2013-11-04 15:58 ` Gregory Maxwell
2013-11-04 14:26 ` Peter Todd
2013-11-04 14:34 ` Pieter Wuille
2013-11-04 14:46 ` Peter Todd
[not found] ` <CABT1wWm1NzKSS9H=Qh3Z6pFmNHbOFKC12WaE=b3kE0mNsRgfmw@mail.gmail.com>
2013-11-04 15:04 ` Peter Todd
[not found] ` <CABT1wWmONUeOWRg-=FKr88bgBQf0un4bvjYW2h8d-10ys-VKtA@mail.gmail.com>
2013-11-04 15:46 ` Peter Todd
[not found] ` <CABT1wWmM466jWWdWAo5GmzP58xJFT70Vcr74ta+2QF2fWT+1SA@mail.gmail.com>
2013-11-04 16:07 ` Peter Todd
[not found] ` <CABT1wWm5BDZf7U40pOqZvTqdOKeTWUTekjUNckq5McMV=LDu_g@mail.gmail.com>
2013-11-04 16:51 ` Peter Todd
[not found] ` <CABT1wWmwb17b4ACHMmDKqd94tUSKsvwAPx344mZ0VS+47myeWg@mail.gmail.com>
2013-11-04 21:04 ` Peter Todd
2013-11-04 21:45 ` Alan Reiner
2013-11-04 22:03 ` Peter Todd
2013-11-04 15:27 ` Mike Hearn
2013-11-04 17:36 ` Peter Todd
2013-11-04 15:51 ` Gregory Maxwell
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