From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1YYMbk-0004qr-NP for bitcoin-development@lists.sourceforge.net; Wed, 18 Mar 2015 22:38:36 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.214.195 as permitted sender) client-ip=209.85.214.195; envelope-from=dennis.jm.sullivan@gmail.com; helo=mail-ob0-f195.google.com; Received: from mail-ob0-f195.google.com ([209.85.214.195]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1YYMbj-0005LO-HQ for bitcoin-development@lists.sourceforge.net; Wed, 18 Mar 2015 22:38:36 +0000 Received: by obcwp18 with SMTP id wp18so2399780obc.3 for ; Wed, 18 Mar 2015 15:38:30 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.182.242.106 with SMTP id wp10mr5771797obc.14.1426718310128; Wed, 18 Mar 2015 15:38:30 -0700 (PDT) Received: by 10.202.62.4 with HTTP; Wed, 18 Mar 2015 15:38:30 -0700 (PDT) Date: Wed, 18 Mar 2015 22:38:30 +0000 Message-ID: From: Dennis Sullivan To: bitcoin-development@lists.sourceforge.net Content-Type: multipart/alternative; boundary=e89a8ff2521a11e352051197be14 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 (dennis.jm.sullivan[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: 1YYMbj-0005LO-HQ Subject: [Bitcoin-development] Are Instant Confirmations safe? 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: Wed, 18 Mar 2015 22:38:36 -0000 --e89a8ff2521a11e352051197be14 Content-Type: text/plain; charset=UTF-8 Hello. This is my first time posting to this list. I wanted to ask your opinions on something relating to confirmation times. I recently read about a "transaction locking" proposal which claims to make it possible to accept 0-conf transactions with guarantee they will get mined. This seems rather dubious to me, because if there was merit to the system, I would have already expected to see discussion on this list regarding it. The scheme operates as follows: As implemented into Darkcoin, an InstantX transaction is broadcast spending certain outputs. Certain nodes determined deterministically will sign a message which is relayed across the network locking this tx in mempool such it's inputs cannot be double spent. All nodes are instructed to reject any conflicting transactions and flush out any existing txs in the mempool that conflict with this "locked" tx. From this point onwards, the network will refuse to relay double spends and will also reject blocks that contain a conflicting tx thus forcing miners to play ball. The idea is once a transaction receives a "consensus lock" across nodes in the mempool, the tx will eventually get mined as there is no way it can be double spent and no way a miner can mine a double spend of the consensus locked transaction. At the very least, this seems like it could be turned in on itself to fork the network because of the ability to cause blocks to be rejected. I am sure there is an attack vector there somewhere. A full explanation is published in this paper: https://www.darkcoin.io/wp-content/uploads/2014/09/InstantTX.pdf Dennis --e89a8ff2521a11e352051197be14 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Hello. This is my first time posting to this list. I = wanted to ask your opinions on something relating to confirmation times.

I recently read about a "transaction locking" p= roposal which claims to make it possible to accept 0-conf transactions with= guarantee they will get mined. This seems rather dubious to me, because if= there was merit to the system, I would have already expected to see discus= sion on this list regarding it.

The scheme operates as follows:

As implemented into Darkcoin, an InstantX transaction= is broadcast spending certain outputs. Certain nodes determined determinis= tically will=C2=A0sign a message which is relayed across the network lockin= g this tx in mempool such it's inputs cannot be double spent. All nodes= are instructed to reject any conflicting transactions and flush out any ex= isting txs in the mempool that conflict with this "locked" tx. Fr= om this point onwards, the network will refuse to relay double spends and w= ill also reject blocks that contain a conflicting tx thus forcing miners to= play ball.

The idea is once a transaction receive= s a "consensus lock" across nodes in the mempool, the tx will eve= ntually get mined as there is no way it can be double spent and no way a mi= ner can mine a double spend of the consensus locked transaction. At the ver= y least, this seems like it could be turned in on itself to fork the networ= k because of the ability to cause blocks to be rejected. I am sure there is= an attack vector there somewhere.

A full explanat= ion is published in this paper:=C2=A0https://www.darkcoin.io/wp-content/u= ploads/2014/09/InstantTX.pdf

Dennis
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