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Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191]
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From: Tamas Blummer <tamas@bitsofproof.com>
In-Reply-To: <5432974B.4000606@certimix.com>
Date: Mon, 6 Oct 2014 06:29:15 -0700
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Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] The Bitcoin Freeze on Transaction Attack
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Sergio,

you can call this an ORBS attack or an attempt of ad-hoc coalition =
forming for a fork.

Preparation Step:
Include a transaction sending a sizable amount between two of your own =
addresses in every block.
Miner can do this at zero cost in their own blocks.

Execution:
Embed into the preferred fork a transaction double spending the regular =
do-nothing transaction with one that offers a sufficiently high fee. =
This offers inceptive to rational miner to join the ad-hoc coalition for =
that fork.

Attempting to form an ad-hoc coalition using above steps is open to =
anyone, just cheaper and easier to execute for a miner.=20

Fortunately cost for (cumulative) proof-of-work creates a lower bound to =
the incentive that need to be offered. So your worry
of times where block subsidy is low is unwarranted as cost of POW will =
be high.

I do not think =93disallowing=94 the implementation of rational mining =
is a viable option, since no one needs permission to implement whatever =
optimization he thinks is profitable and within the rules.

Tamas Blummer

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