From: Elden Tyrell <tyrell.elden@gmail•com>
To: bitcoin-development@lists•sourceforge.net
Subject: Re: [Bitcoin-development] does "stubbing" off Merkle trees reduce initial download bandwidth?
Date: Mon, 2 Jan 2012 17:39:09 -0800 [thread overview]
Message-ID: <jdtm7t$4ed$1@dough.gmane.org> (raw)
In-Reply-To: <CAAS2fgTOZKM9c=UvfVW1rajnPQVQMNS4mR5KUqq8p0HreG=vuQ@mail.gmail.com>
On 2012-01-02 14:41:10 -0800, Gregory Maxwell said:
> make this possible: https://bitcointalk.org/index.php?topic=21995.0
Neat! I had a similar idea but you've clearly beat me to [a big part of] it.
> Er, no— if a node controls the private keys for a transaction, and
> that transaction makes it into the chain then it can safely assume
> that its unspent (at least once its buried a few blocks into the
> chain).
I'm not so sure about that. If you accept X successor blocks as proof
that none of the transactions in a block re-used an output, then the
cost of attacking is X*50BTC since the hashpower needed for the attack
could have earned that much reward.
However, an attacker could use the same faked X-block sequence to
attack multiple clients by putting several double-spend transactions in
the first faked block. This would spread out the cost over more than
one attack. So simply checking that the value of the transaction is
less than X*50 isn't necessarily enough, although the logistics of the
attack aren't exactly easy.
There's also the question of knowing what the difficulty for those X
blocks ought to be. If the attacker controls your network connection
(e.g. your ISP attacks you) you wouldn't be able to get a second
opinion on how high the difficulty ought to be, and might get fooled by
X very-low-difficulty blocks that were each produced with a lot less
than 50BTC worth of hashpower.
- e
next prev parent reply other threads:[~2012-01-03 1:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-02 5:04 Elden Tyrell
2012-01-02 13:31 ` Christian Decker
2012-01-02 22:23 ` Elden Tyrell
2012-01-02 22:41 ` Gregory Maxwell
2012-01-03 1:39 ` Elden Tyrell [this message]
2012-01-05 23:30 ` Mike Hearn
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