From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 3626140D for ; Sun, 11 Dec 2016 23:23:18 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from ob1-4.mailhostbox.com (ob1-4.mailhostbox.com [162.222.225.13]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 6634AAA for ; Sun, 11 Dec 2016 23:23:12 +0000 (UTC) Received: from [0.0.0.0] (unknown [94.242.228.174]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) (Authenticated sender: s7r@sky-ip.org) by outbound.mailhostbox.com (Postfix) with ESMTPSA id 0142A1A1A53; Sun, 11 Dec 2016 23:23:08 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sky-ip.org; s=20110108; t=1481498590; bh=TrV6OGsLDPKUEj2nZaEqKwQt1ZIxQ0WZQaNfAg/L6GE=; h=Reply-To:Subject:References:To:Cc:From:Date:In-Reply-To; b=UKmKwSfFeCCZFTH7zmP/sb23e95jhm724YRrC2LMv8aro37in7u6wxVnoaTSXOtsT vG1QFABOeXJ5tGh9Ign0oNUeVc/l0xvbZw05Fy6HT7eRzxaBJXBD7FHW8KEN2evOmZ D+erkLeNWcJ3trUQd1Snff7XYgimXOi5ZvZ1d9BU= Reply-To: s7r@sky-ip.org References: To: Andrew Johnson , Bitcoin Dev From: s7r Message-ID: <8679ecea-b449-0f5a-d4d7-1f23ae6e29b2@sky-ip.org> Date: Mon, 12 Dec 2016 01:22:53 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="SXwRARS1R8iiER60wdA55aKxfJ28OA16V" X-CMAE-Score: 0 X-CMAE-Analysis: v=2.1 cv=YravP9sX c=1 sm=1 tr=0 a=OhT2UXNAK9XbldXxFrtDUw==:117 a=OhT2UXNAK9XbldXxFrtDUw==:17 a=L9H7d07YOLsA:10 a=9cW_t1CCXrUA:10 a=s5jvgZ67dGcA:10 a=13zjGPudsaEWiJwPRgMA:9 a=WbPmnYzAfxEA:10 a=0sRFVnq9k0wZibWCWSEA:9 a=QEXdDO2ut3YA:10 a=Ql4hTJPka4aepvyxXiAA:9 X-Scanned-By: MIMEDefang 2.72 on 172.18.214.92 X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_NONE,URIBL_BLACK autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: Re: [bitcoin-dev] Managing block size the same way we do difficulty (aka Block75) X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 11 Dec 2016 23:23:18 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --SXwRARS1R8iiER60wdA55aKxfJ28OA16V Content-Type: multipart/mixed; boundary="b6rVpjReHNaOW4didmo8eksQJJDNQhjcw"; protected-headers="v1" From: s7r Reply-To: s7r@sky-ip.org To: Andrew Johnson , Bitcoin Dev Cc: "t. khan" Message-ID: <8679ecea-b449-0f5a-d4d7-1f23ae6e29b2@sky-ip.org> Subject: Re: [bitcoin-dev] Managing block size the same way we do difficulty (aka Block75) References: In-Reply-To: --b6rVpjReHNaOW4didmo8eksQJJDNQhjcw Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Andrew Johnson wrote: > "You miss something obvious that makes this attack actually free of cos= t. > Nothing will "cost them more in transaction fees". A miner can create > thousands of transactions paying to himself, and not broadcast them to > the network, but hold them and include them in the blocks he mines. The= > fees are collected by him because transactions are included in a block > that he mined and the left amount is in another wallet of the same > person. Repeat this continuously to fill blocks." >=20 > This is easily detectable as long as the network isn't heavily > partitioned(which is an assumption we make today in order for > transaction propagation to work reliably as well as for xThin and > CompactBlocks to work effectively to reduce block transmission time).=20 > Other miners would have an incentive to intentionally orphan blocks tha= t > contained a large number of transactions that their nodes were unaware = of. >=20 > I don't think this sort of attack would last long. Even later when > subsidies are drastically reduced, you would still lose out on > significant genuine fee revenue if your orphan rate increased even > 10%(one out of ten of your poison blocks intentionally orphaned by > another miner). >=20 I disagree. I didn't say this is impossible to detect, but it is hard to act against it. One miner orphaning the block intentionally is very unlikely if that miner acts rationally. It would only make sense if 51% of the hash rate would intentionally orphan it. Otherwise the miner who intentionally orphans a valid block, let's say block X, has to continue to mine one in its place on top of block X-1, and by the time he finds one: a) his block X' is rejected by other miners because they already have a valid block X on top of which they already started to mine; b) block X+1 was already found and broadcasted, so the miner who orphaned X intentionally is on the shorter chain ignored by the network. So, one miner cannot do anything about it. Even a pool cannot do anything about it, because the loss is greater. You need 51% of the hash rate to intentionally orphan it, and all the miners forming 51% need to be colluding and know for sure that every one will intentionally orphan the said block, otherwise there's a huge risk of loss for who does it. Nobody would gamble to do this (I am not sure if gambling is the right word, since the loss is 100% sure here). But, we are not discussing 51% attacks because those are a different topic. --b6rVpjReHNaOW4didmo8eksQJJDNQhjcw-- --SXwRARS1R8iiER60wdA55aKxfJ28OA16V Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (MingW32) iQEcBAEBCAAGBQJYTd/YAAoJEIN/pSyBJlsRfOAIALCQ3KTAi9hfPV00v4/+JNGL nxhc5aCIyuj68oK7dAKFq5N8VbFYRaxSGfACvW+yAPERXQnvVxa++0yETOL8U835 oeNNyn1wbO6dNl//fU50RYxeAaXT4/jugD6+hU6ibsnflUNRkM9yQd6yr/6WWHJE yZhMhBqEh2VIyhzJpdrkQxj/XnGpbgzVMNvaEToUnZbRc9zKneO9FlUUptsW+jpK tIQ3UjSe+8siQlZnw6xSOKI7N05Yn40tWb52+EDUPWLnuVERj0HqH7tuM1hkH8bE rtYzHv9zokG6QdLPqH0+OUmB/BWJ3giJMlmnZ3l5JPW+YDoqogvuen78GsjSdmw= =uxFh -----END PGP SIGNATURE----- --SXwRARS1R8iiER60wdA55aKxfJ28OA16V--