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| author | Peter Todd <pete@petertodd.org> | 2013-11-15 05:58:37 -0500 |
|---|---|---|
| committer | bitcoindev <bitcoindev@gnusha.org> | 2013-11-15 10:58:54 +0000 |
| commit | 93480bf65d00360cdeac6c5474d6b8ae0119c179 (patch) | |
| tree | 561b46c5ddef925434b4bfc68f8be0ae52031f3d | |
| parent | 3afd181a02c8f87c938df8ed00f7de6612e95515 (diff) | |
| download | pi-bitcoindev-93480bf65d00360cdeac6c5474d6b8ae0119c179.tar.gz pi-bitcoindev-93480bf65d00360cdeac6c5474d6b8ae0119c179.zip | |
Re: [Bitcoin-development] we can all relax now
| -rw-r--r-- | 93/40cc08865bfbb02ef8366737f83d92f0c898e1 | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/93/40cc08865bfbb02ef8366737f83d92f0c898e1 b/93/40cc08865bfbb02ef8366737f83d92f0c898e1 new file mode 100644 index 000000000..293deba21 --- /dev/null +++ b/93/40cc08865bfbb02ef8366737f83d92f0c898e1 @@ -0,0 +1,164 @@ +Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] + helo=mx.sourceforge.net) + by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) + (envelope-from <pete@petertodd.org>) id 1VhH70-0006Cp-K4 + for Bitcoin-development@lists.sourceforge.net; + Fri, 15 Nov 2013 10:58:54 +0000 +Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of petertodd.org + designates 62.13.148.112 as permitted sender) + client-ip=62.13.148.112; envelope-from=pete@petertodd.org; + helo=outmail148112.authsmtp.co.uk; +Received: from outmail148112.authsmtp.co.uk ([62.13.148.112]) + by sog-mx-2.v43.ch3.sourceforge.com with esmtp (Exim 4.76) + id 1VhH6z-0005wn-Gn for Bitcoin-development@lists.sourceforge.net; + Fri, 15 Nov 2013 10:58:54 +0000 +Received: from mail-c237.authsmtp.com (mail-c237.authsmtp.com [62.13.128.237]) + by punt9.authsmtp.com (8.14.2/8.14.2) with ESMTP id rAFAwg42067184; + Fri, 15 Nov 2013 10:58:42 GMT +Received: from savin (76-10-178-109.dsl.teksavvy.com [76.10.178.109]) + (authenticated bits=128) + by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id rAFAwcdk053943 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); + Fri, 15 Nov 2013 10:58:40 GMT +Date: Fri, 15 Nov 2013 05:58:37 -0500 +From: Peter Todd <pete@petertodd.org> +To: Daniel Lidstrom <lidstrom83@gmail.com> +Message-ID: <20131115105837.GE17034@savin> +References: <5279D49D.5050807@jerviss.org> + <CAJHLa0N1-8LfFuWq=vS0r-t2Bt-qZ6yKuGjrnicUOj+K6Gpx5A@mail.gmail.com> + <CANOOu=-MsPPgACKcHvsvtFAOAiULL+BOQvJz1tC3L=nT8wN01Q@mail.gmail.com> + <20131107034404.GA5140@savin> + <CABsx9T35Po7pUb2sr15zD5WODYqR4-xNvJD0Jz5+Of3d-NjPdg@mail.gmail.com> + <20131107132442.GB22476@savin> + <CANEZrP3T4qsz8qqPxqtP5oXNYA_WT5OQPrC2uAKuQyDqJ0N9Rw@mail.gmail.com> + <CADjHg8GNuoPQ7Ama0A=iGmboeE_T5LrLRHPKyvQqWwKAjT3K3w@mail.gmail.com> +MIME-Version: 1.0 +Content-Type: multipart/signed; micalg=pgp-sha256; + protocol="application/pgp-signature"; boundary="BZaMRJmqxGScZ8Mx" +Content-Disposition: inline +In-Reply-To: <CADjHg8GNuoPQ7Ama0A=iGmboeE_T5LrLRHPKyvQqWwKAjT3K3w@mail.gmail.com> +User-Agent: Mutt/1.5.21 (2010-09-15) +X-Server-Quench: e38c8c85-4de4-11e3-94fa-002590a135d3 +X-AuthReport-Spam: If SPAM / abuse - report it at: + http://www.authsmtp.com/abuse +X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR + bwdMdwcUFloCAgsB AmUbWlReVVV7XWI7 bAxPbAVDY01GQQRq + WVdMSlVNFUsqcGpw QU1KCRl3dAxCezBy Y05jWj4OX0wpfRV1 + R1NQQTgCeGZhPWMC WUQOJh5UcAFPdx8U a1N6AHBDAzANdhES + HhM4ODE3eDlSNilR RRkIIFQOdA4UE3Y3 ThZKFDErVVcIQywj ZxohNTb9 +X-Authentic-SMTP: 61633532353630.1024:706 +X-AuthFastPath: 0 (Was 255) +X-AuthSMTP-Origin: 76.10.178.109/587 +X-AuthVirus-Status: No virus detected - but ensure you scan with your own + anti-virus system. +X-Spam-Score: -1.5 (-) +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 SPF_PASS SPF: sender matches SPF record + 0.0 URIBL_BLOCKED ADMINISTRATOR NOTICE: The query to URIBL was blocked. + See + http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block + for more information. [URIs: petertodd.org] +X-Headers-End: 1VhH6z-0005wn-Gn +Cc: Bitcoin Dev <Bitcoin-development@lists.sourceforge.net>, webmaster@cex.io, + webmaster@ghash.io +Subject: Re: [Bitcoin-development] we can all relax now +X-BeenThere: bitcoin-development@lists.sourceforge.net +X-Mailman-Version: 2.1.9 +Precedence: list +List-Id: <bitcoin-development.lists.sourceforge.net> +List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>, + <mailto:bitcoin-development-request@lists.sourceforge.net?subject=unsubscribe> +List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=bitcoin-development> +List-Post: <mailto:bitcoin-development@lists.sourceforge.net> +List-Help: <mailto:bitcoin-development-request@lists.sourceforge.net?subject=help> +List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>, + <mailto:bitcoin-development-request@lists.sourceforge.net?subject=subscribe> +X-List-Received-Date: Fri, 15 Nov 2013 10:58:54 -0000 + + +--BZaMRJmqxGScZ8Mx +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +Content-Transfer-Encoding: quoted-printable + +On Thu, Nov 07, 2013 at 11:28:52AM -0700, Daniel Lidstrom wrote: +> Hey Peter, something seems wrong with your above analysis: I think a miner +> would withhold his block not because it leads to a greater probability of +> winning the next one, but because it increases his expected revenue. +>=20 +> Suppose a cabal with fraction q of the total hashing power is n blocks +> ahead on a secret branch of that has mined r_tot coins, and let r_next be +> its next block's reward. If the cabal chooses not to broadcast its secret +> chain until at least the next block, its expected revenue after the next +> block is found is +>=20 +> (1 - (1-q)^(n+1))*(r_tot + r_next) +>=20 +> If it does broadcast, its expected revenue after the next block is found = +is +>=20 +> r_tot + q * r_next +>=20 +> If the cabal seeks only to maximize immediate revenue, then after a bit of +> algebra we find that it will withhold its chain if +>=20 +> q > 1 - ( 1 + r_tot / r_next )^(-1/n) +>=20 +> So if the cabal has just mined his first block off of the public chain, +> i.e. n =3D 1, and if the block reward is relatively stable, i.e. r_next = +=3D +> r_tot, then it needs q > 50% to profitably withhold, not the 29.2% you +> calculated. +>=20 +> From this formula we can also see that if the miner wins the race and +> withholds again, then he must grow q to compensate for the increase in +> r_tot, and any decrease in n. So generally publication becomes +> increasingly in the cabal's interest, and secret chains will tend not to +> grow too large (intuition tells me that simulations using the above formu= +la +> should bear this out). +>=20 +> This seem correct to you? + +Remember how I started off by asking what was the correct strategy if a +miner wanted to get more blocks than their *competition*, not more +blocks in total. In some scenarios that strategy is the one that +maximizes returns, such as the case when you make your returns from +transaction fees, especially without a blocksize limit restricting how +many fee paying transactions you can stuff in your blocks. It's not +correct to say the cabal is trying to maximize immediate revenue. + +As for the length of those secret chains, at every step you of course +want to weigh the value of the blocks you have found against the risk +that someone else catches up, and when it makes sense, publish some or +all. + +--=20 +'peter'[:-1]@petertodd.org +0000000000000000b4ff49cd2cad865d6cbca99828987a02f3d5f41067eab00a + +--BZaMRJmqxGScZ8Mx +Content-Type: application/pgp-signature; name="signature.asc" +Content-Description: Digital signature + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.4.12 (GNU/Linux) + +iQGrBAEBCACVBQJShf5dXhSAAAAAABUAQGJsb2NraGFzaEBiaXRjb2luLm9yZzAw +MDAwMDAwMDAwMDAwMDBiNGZmNDljZDJjYWQ4NjVkNmNiY2E5OTgyODk4N2EwMmYz +ZDVmNDEwNjdlYWIwMGEvFIAAAAAAFQARcGthLWFkZHJlc3NAZ251cGcub3JncGV0 +ZUBwZXRlcnRvZC5vcmcACgkQJIFAPaXwkftfTwgAkfxoN0j1V52KDAWm+zCaVnbc +L6NfXySpFK20KtsjoiijzMLtCoq29hqjLJwbVAYlikH4Wzd7p2xPMcsee06sAyTI +6DPicmk8ciKYG4ss3JyVGH1zE88mYikKEGcN9niVMktUcOLhkF+bB0mQwiYL/9Fm +dBkISVLTTJO5cy4rs+93h9/+VgLskO8v3F5EiJUwgzp2WiPUzJXlBnTibCMxEiMN +/fyuqdGv9rfVrlrogOJSFyTsYM2P+2+SWNoU650PRwnCnqqTk+/hmE5WG+26PG2V +TRtYeaAdjc1NtHFl2KxCfdaCpO4NbkjzuAFfOnoW6MTa3eqwkqE9pKDfrJ9eJQ== +=aSU+ +-----END PGP SIGNATURE----- + +--BZaMRJmqxGScZ8Mx-- + + |