Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1WYLKS-0007Hw-64 for bitcoin-development@lists.sourceforge.net; Thu, 10 Apr 2014 20:12:08 +0000 Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.216.181 as permitted sender) client-ip=209.85.216.181; envelope-from=tier.nolan@gmail.com; helo=mail-qc0-f181.google.com; Received: from mail-qc0-f181.google.com ([209.85.216.181]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WYLKR-0007BG-0O for bitcoin-development@lists.sourceforge.net; Thu, 10 Apr 2014 20:12:08 +0000 Received: by mail-qc0-f181.google.com with SMTP id x3so5000187qcv.12 for ; Thu, 10 Apr 2014 13:12:01 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.224.163.73 with SMTP id z9mr23443548qax.90.1397160721525; Thu, 10 Apr 2014 13:12:01 -0700 (PDT) Received: by 10.140.25.86 with HTTP; Thu, 10 Apr 2014 13:12:00 -0700 (PDT) In-Reply-To: References: Date: Thu, 10 Apr 2014 21:12:00 +0100 Message-ID: From: Tier Nolan To: Pieter Wuille Content-Type: multipart/alternative; boundary=089e0158b03080362204f6b5d4b0 X-Spam-Score: -0.6 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (tier.nolan[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 1.0 HTML_MESSAGE BODY: HTML included in message -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1WYLKR-0007BG-0O Cc: Bitcoin Dev , Paul Rabahy Subject: Re: [Bitcoin-development] Chain pruning X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Apr 2014 20:12:08 -0000 --089e0158b03080362204f6b5d4b0 Content-Type: text/plain; charset=ISO-8859-1 On Thu, Apr 10, 2014 at 7:32 PM, Pieter Wuille wrote: > If you trust hashrate for determining which UTXO set is valid, a 51% > attack becomes worse in that you can be made to believe a version of > history which is in fact invalid. > If there are invalidation proofs, then this isn't strictly true. If you are connected to 10 nodes and only 1 is honest, it can send you the proof that your main chain is invalid. For bad scripts, it shows you the input transaction for the invalid input along with the merkle path to prove it is in a previous block. For double spends, it could show the transaction which spent the output. Double spends are pretty much the same as trying to spend non-existent outputs anyway. If the UTXO set commit was actually a merkle tree, then all updates could be included. Blocks could have extra data with the proofs that the UTXO set is being updated correctly. To update the UTXO set, you need the paths for all spent inputs. It puts a large load on miners to keep things working, since they have to run a full node. If they commit the data to the chain, then SPV nodes can do local checking. One of them will find invalid blocks eventually (even if one of the other miners don't). > > -- > Pieter > > > ------------------------------------------------------------------------------ > Put Bad Developers to Shame > Dominate Development with Jenkins Continuous Integration > Continuously Automate Build, Test & Deployment > Start a new project now. Try Jenkins in the cloud. > http://p.sf.net/sfu/13600_Cloudbees > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > --089e0158b03080362204f6b5d4b0 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
On T= hu, Apr 10, 2014 at 7:32 PM, Pieter Wuille <pieter.wuille@gmail.com<= /a>> wrote:
If you trust hashrate for determining which UTXO set is valid, a 51%
attack becomes worse in that you can be made to believe a version of
history which is in fact invalid.

If th= ere are invalidation proofs, then this isn't strictly true.

If you are connected to 10 nodes and only 1 is honest, it can send y= ou the proof that your main chain is invalid.

For bad scripts, it shows you the input transaction for the = invalid input along with the merkle path to prove it is in a previous block= .

For double spends, it could show the transaction which = spent the output.

Double spends are pretty much the same as trying to spend no= n-existent outputs anyway.

If the UTXO set commit was act= ually a merkle tree, then all updates could be included.

Blocks could have extra data with the proofs that the UTXO set is being upd= ated correctly.

To update the UTXO set, you ne= ed the paths for all spent inputs.

It puts a large load o= n miners to keep things working, since they have to run a full node.=A0
If they commit the data to the chain, then SPV nodes can do = local checking.

One of them will find invalid blocks even= tually (even if one of the other miners don't).

--
Pieter

---------------------------------------------------------------------------= ---
Put Bad Developers to Shame
Dominate Development with Jenkins Continuous Integration
Continuously Automate Build, Test & Deployment
Start a new project now. Try Jenkins in the cloud.
http://p.= sf.net/sfu/13600_Cloudbees
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