From: Mike Hearn <mike@plan99•net>
To: Mark Friedenbach <mark@monetize•io>
Cc: Bitcoin Dev <bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] Committing to extra block data/a better merge-mine standard
Date: Mon, 4 Nov 2013 21:10:04 +0100 [thread overview]
Message-ID: <CANEZrP17hEuFmWiN1scq42mJzcXOBEHHAK8aLd_idCQ6ZqvpYw@mail.gmail.com> (raw)
In-Reply-To: <5277FB21.3050306@monetize.io>
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Yes, sure. I was talking about the case of transiently relayed data, like
IP addresses.
On Mon, Nov 4, 2013 at 8:53 PM, Mark Friedenbach <mark@monetize•io> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> 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.
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG/MacGPG2 v2.0.19 (Darwin)
> Comment: GPGTools - http://gpgtools.org
> Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/
>
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>
> ------------------------------------------------------------------------------
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next prev parent reply other threads:[~2013-11-04 20:10 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
2013-11-04 20:10 ` Mike Hearn [this message]
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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