From: Peter Todd <pete@petertodd.org>
To: Natanael <natanael.l@gmail.com>
Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] bitcoinj 0.11 released, with p2sh, bip39 and payment protocol support
Date: Tue, 4 Feb 2014 11:04:14 -0500 [thread overview]
Message-ID: <20140204160414.GA23803@savin> (raw)
In-Reply-To: <CAAt2M1-LZ1APX9F93WE7Z877-WxqvJFbGaUmu5eriRGwvAOESw@mail.gmail.com>
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On Tue, Feb 04, 2014 at 04:17:47PM +0100, Natanael wrote:
> Because it's trivial to create collisions! You can choose exactly what
> output you want. That's why XOR is a very bad digest scheme.
You're close, but not quite.
So, imagine you have a merkle tree, and you're trying to timestamp some
data at the bottom of the tree. Now you can successfully timestamp the
top digest in the Bitcoin blockchain right, and be sure that digest
existed before some time. But what about the digests at the bottom of
the tree? What can an attacker do exactly to make a fake timestamp if
the tree is using XOR rather than a proper hash function?
--
'peter'[:-1]@petertodd.org
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next prev parent reply other threads:[~2014-02-04 16:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-04 12:01 [Bitcoin-development] bitcoinj 0.11 released, with p2sh, bip39 and payment protocol support Mike Hearn
2014-02-04 13:03 ` Peter Todd
2014-02-04 13:13 ` Mike Hearn
2014-02-04 13:17 ` Peter Todd
2014-02-04 14:43 ` Jeff Garzik
2014-02-04 14:46 ` Peter Todd
2014-02-04 15:17 ` Natanael
2014-02-04 16:04 ` Peter Todd [this message]
2014-02-05 7:57 ` Jeremy Spilman
2014-02-05 15:09 ` Brooks Boyd
2014-02-07 9:21 ` Peter Todd
2014-02-07 10:48 ` Mike Hearn
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