Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 721C6FBF for ; Fri, 25 Dec 2015 12:00:06 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from c.mail.sonic.net (c.mail.sonic.net [64.142.111.80]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id C6500A5 for ; Fri, 25 Dec 2015 12:00:05 +0000 (UTC) Received: from [192.168.1.190] (63.135.62.197.nwinternet.com [63.135.62.197] (may be forged)) (authenticated bits=0) by c.mail.sonic.net (8.15.1/8.15.1) with ESMTPSA id tBPBxu3I030688 (version=TLSv1 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT); Fri, 25 Dec 2015 03:59:57 -0800 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Content-Type: multipart/signed; boundary="Apple-Mail=_EAA8C5C6-89A8-462E-9728-F8DFF91CB830"; protocol="application/pgp-signature"; micalg=pgp-sha512 X-Pgp-Agent: GPGMail 2.5.2 From: Jonathan Toomim In-Reply-To: Date: Fri, 25 Dec 2015 04:00:11 -0800 Message-Id: <8BA2CF44-4237-460E-8339-F22A29504AE5@toom.im> References: <20151219184240.GB12893@muck> <219f125cee6ca68fd27016642e38fdf1@xbt.hk> <20151220132842.GA25481@muck> To: Ittay X-Mailer: Apple Mail (2.1878.6) X-Sonic-CAuth: UmFuZG9tSVYG27lgQAiCeVwg8cDp0ipp5Xhhfr6yg2VjUumfzt7T6PQs7h9NDDLZ2Jg5nMVpzDhzgTgZuKxXv17fsHJUXJ6q X-Sonic-ID: C;VozEA/+q5RGWE/8vZz0oYQ== M;vBZ+BP+q5RGWE/8vZz0oYQ== X-Sonic-Spam-Details: 3.8/5.0 by cerberusd X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,HTML_MESSAGE, RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] We need to fix the block withholding attack X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 25 Dec 2015 12:00:06 -0000 --Apple-Mail=_EAA8C5C6-89A8-462E-9728-F8DFF91CB830 Content-Type: multipart/alternative; boundary="Apple-Mail=_7EFA8C1F-F68C-47DB-B550-2A2711E0E268" --Apple-Mail=_7EFA8C1F-F68C-47DB-B550-2A2711E0E268 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii On Dec 25, 2015, at 3:15 AM, Ittay via bitcoin-dev = wrote: > Treating the pool block withholding attack as a weapon has bad = connotations, and I don't think anyone directly condones such an attack. I directly condone the use of block withholding attacks whenever pools = get large enough to perform selfish mining attacks. Selfish mining and = large, centralized pools also have bad connotations. It's an attack against pools, not just large pools. Solo miners are = immune. As such, the presence or use of block withholding attacks makes = Bitcoin more similar to Satoshi's original vision. One of the issues = with mining centralization via pools is that miners have a direct = financial incentive to stay relatively small, but pools do not. = Investing in mining is a zero-sum game, where each miner gains revenue = by making investments at the expense of existing miners. This also means = that miners take revenue from themselves when they upgrade their = hashrate. If a miner already has 1/5 of the network hashrate, then the = marginal revenue for that miner of adding 1 TH/s is only 4/5 of the = marginal revenue for a miner with 0% of the network and who adds 1 TH/s. = The bigger you get, the smaller your incentive to get bigger. This incentive applies to miners, but it does not apply to pools. Pools = have an incentive to get as big as possible (except for social backlash = and altruistic punishment issues). Pools are the problem. I think we = should be looking for ways of making pooled mining less profitable than = solo mining or p2pool-style mining. Block withholding attacks are one = such tool, and maybe the only usable tool we'll get. If we have to = choose between making bitcoin viable long-term and avoiding things with = bad connotations, it might be better to let our hands get a little bit = dirty. I don't intend to perform any such attacks myself. I like to keep my hat = a nice shiny white. However, if anyone else were to perform such an = attack, I would condone it. P.S.: Sorry, pool operators. I have nothing against you personally. I = just think pools are dangerous, and I wish they didn't exist. --Apple-Mail=_7EFA8C1F-F68C-47DB-B550-2A2711E0E268 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii
On Dec 25, 2015, at 3:15 AM, Ittay via = bitcoin-dev <bitcoin-dev@lists.li= nuxfoundation.org> wrote:

Treating the pool block withholding attack as a weapon has = bad connotations, and I don't think anyone directly condones such an = attack.

I directly condone the = use of block withholding attacks whenever pools get large enough to = perform selfish mining attacks. Selfish mining and large, centralized = pools also have bad connotations.

It's an = attack against pools, not just large pools. Solo miners are immune. As = such, the presence or use of block withholding attacks makes Bitcoin = more similar to Satoshi's original vision. One of the issues with mining = centralization via pools is that miners have a direct financial = incentive to stay relatively small, but pools do not. Investing in = mining is a zero-sum game, where each miner gains revenue by making = investments at the expense of existing miners. This also means that = miners take revenue from themselves when they upgrade their hashrate. If = a miner already has 1/5 of the network hashrate, then the marginal = revenue for that miner of adding 1 TH/s is only 4/5 of the marginal = revenue for a miner with 0% of the network and who adds 1 TH/s. The = bigger you get, the smaller your incentive to get = bigger. 

This incentive applies to miners, = but it does not apply to pools. Pools have an incentive to get as big as = possible (except for social backlash and altruistic punishment issues). = Pools are the problem. I think we should be looking for ways of making = pooled mining less profitable than solo mining or p2pool-style mining. = Block withholding attacks are one such tool, and maybe the only usable = tool we'll get. If we have to choose between making bitcoin viable = long-term and avoiding things with bad connotations, it might be better = to let our hands get a little bit dirty.

I = don't intend to perform any such attacks myself. I like to keep my hat a = nice shiny white. However, if anyone else were to perform such an = attack, I would condone it.

P.S.: Sorry, pool = operators. I have nothing against you personally. I just think pools are = dangerous, and I wish they didn't exist.
= --Apple-Mail=_7EFA8C1F-F68C-47DB-B550-2A2711E0E268-- --Apple-Mail=_EAA8C5C6-89A8-462E-9728-F8DFF91CB830 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQEcBAEBCgAGBQJWfS/NAAoJEIEuMk4MG0P1cxQH/A+15Yp/NU6bcRVj4lQUtuxk AqBbp6klno3nMs1KO2ffsqShhQ/9stN6OdrzwKOhDybOxDXQ3TMMud68FG1kKQMu OqUUgHIXXcb4SnW04sxJ+QMZBSFSQsKlrdDt0adHNoJzCRWozu5MOll2t0OML6/L Wdjao8pR9DWjbwu3QqeY9OOIuCwSRl+NJ6GSiBCVqDLC+byK2SjOg6MYsW5Mr/Bl 1oEYIypFhhCnU8G7C5YdQuK/GYaTSScAY1qcZpuuthcSiYSs997GOFsm0C/xOnqv RevfcE1thxh+WvLmjoRYWTfnRRrq0JZmOmdGjWivHIcOUj0jYGlYxlI02ya2jzs= =xysR -----END PGP SIGNATURE----- --Apple-Mail=_EAA8C5C6-89A8-462E-9728-F8DFF91CB830--