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| author | Jorge Timón <jtimon@jtimon.cc> | 2015-07-12 20:37:19 +0200 |
|---|---|---|
| committer | bitcoindev <bitcoindev@gnusha.org> | 2015-07-12 18:37:21 +0000 |
| commit | 8ba8095bd9038742ca8aaa30e9d2be28db35918a (patch) | |
| tree | 06798dbc4ce949ff59344b50a404a243c0cf2bdc | |
| parent | 0237086b3a92e5f8312d8cbaf03b4618618a1eba (diff) | |
| download | pi-bitcoindev-8ba8095bd9038742ca8aaa30e9d2be28db35918a.tar.gz pi-bitcoindev-8ba8095bd9038742ca8aaa30e9d2be28db35918a.zip | |
Re: [bitcoin-dev] SPV Mining reveals a problematic incentive issue.
| -rw-r--r-- | 70/6241e082f2a6ec05831267bdd063dd418cf0a6 | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/70/6241e082f2a6ec05831267bdd063dd418cf0a6 b/70/6241e082f2a6ec05831267bdd063dd418cf0a6 new file mode 100644 index 000000000..12eedbffc --- /dev/null +++ b/70/6241e082f2a6ec05831267bdd063dd418cf0a6 @@ -0,0 +1,130 @@ +Return-Path: <jtimon@jtimon.cc> +Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org + [172.17.192.35]) + by mail.linuxfoundation.org (Postfix) with ESMTPS id E218A9F2 + for <bitcoin-dev@lists.linuxfoundation.org>; + Sun, 12 Jul 2015 18:37:21 +0000 (UTC) +X-Greylist: whitelisted by SQLgrey-1.7.6 +Received: from mail-wi0-f175.google.com (mail-wi0-f175.google.com + [209.85.212.175]) + by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 14F4D25D + for <bitcoin-dev@lists.linuxfoundation.org>; + Sun, 12 Jul 2015 18:37:20 +0000 (UTC) +Received: by wiga1 with SMTP id a1so51425354wig.0 + for <bitcoin-dev@lists.linuxfoundation.org>; + Sun, 12 Jul 2015 11:37:19 -0700 (PDT) +X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; + d=1e100.net; s=20130820; + h=x-gm-message-state:mime-version:in-reply-to:references:date + :message-id:subject:from:to:cc:content-type + :content-transfer-encoding; + bh=sqYm2FBm4kx1Mas5lhZ4xDPLJz321ubHBZNsERpDXTg=; + b=k7gObErTEbgsSxxkNr8+BH5P2oFhOlxGmraChvY1FVn4YQTxQBeg9NYX6uK/AxKBLc + v7TYZiUXUhK/Vu5JJCf/GNKcy7Evw1BE8ls4y4U5zT1032nVhlggq/NaSKVDhM9sfA4F + zDx/NUE5N9Ea+4HT1ykFpINWPzXkJLynhoO0rHZn8/41wur+wLt4NDiWTzeWHYytvLsy + ImuMxT2ks3FeKXrxAZPCE2j6WUdzIF1K69LhONPJnbpckcGnrcrNFYxl5TqLlzAwo28T + e82d/CWtoREIAQzw7ZaiKbYKs4Nuxkv6PGC3kMFgm7p+Jh1WVwUsN0wonJkGVrpgPFg8 + wpIg== +X-Gm-Message-State: ALoCoQmcoJCU3Wx8IcmXR75y23zamr/B52vGt/i80CDu7LC+sv8NZVmoZz4F4vuGDFt/gq4Bn8l2 +MIME-Version: 1.0 +X-Received: by 10.181.13.195 with SMTP id fa3mr15393762wid.7.1436726239443; + Sun, 12 Jul 2015 11:37:19 -0700 (PDT) +Received: by 10.194.95.168 with HTTP; Sun, 12 Jul 2015 11:37:19 -0700 (PDT) +In-Reply-To: <CAE-z3OWOoHfMaEN04CQ-j8tzmAr1+Evjh+tfHRDbF6F1jxykHA@mail.gmail.com> +References: <CAFdHNGg2dezj4V-i-E6dRLp99nZMQ_ErKdBo0OgQJ=9WPm90jQ@mail.gmail.com> + <CABm2gDoAa5F5crO4enKO-Qqb+Zd3=9b8ohBDYmrygsPSWdevoQ@mail.gmail.com> + <CAE-z3OWOoHfMaEN04CQ-j8tzmAr1+Evjh+tfHRDbF6F1jxykHA@mail.gmail.com> +Date: Sun, 12 Jul 2015 20:37:19 +0200 +Message-ID: <CABm2gDrPesyv95UHfDCRThaEkAQQ+rdQ1FN0ad0mFX9hTRj33A@mail.gmail.com> +From: =?UTF-8?B?Sm9yZ2UgVGltw7Nu?= <jtimon@jtimon.cc> +To: Tier Nolan <tier.nolan@gmail.com> +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, score=-0.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_LOW, + URIBL_BLACK autolearn=no version=3.3.1 +X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on + smtp1.linux-foundation.org +Cc: bitcoin-dev@lists.linuxfoundation.org +Subject: Re: [bitcoin-dev] SPV Mining reveals a problematic incentive issue. +X-BeenThere: bitcoin-dev@lists.linuxfoundation.org +X-Mailman-Version: 2.1.12 +Precedence: list +List-Id: Bitcoin Development Discussion <bitcoin-dev.lists.linuxfoundation.org> +List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/bitcoin-dev>, + <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=unsubscribe> +List-Archive: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/> +List-Post: <mailto:bitcoin-dev@lists.linuxfoundation.org> +List-Help: <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=help> +List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>, + <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=subscribe> +X-List-Received-Date: Sun, 12 Jul 2015 18:37:22 -0000 + +On Sat, Jul 11, 2015 at 12:39 PM, Tier Nolan <tier.nolan@gmail.com> wrote: +> +> +> On Sat, Jul 11, 2015 at 10:24 AM, Jorge Tim=C3=B3n <jtimon@jtimon.cc> wro= +te: +>> +>> I think it would be more rational for them to keep mining on top of the +>> old block until they've fully validated the new block (which shouldn't t= +ake +>> so long anyway), even if this slightly increases the orphan rate. +> +> +> Increased orphan rate means that the network is (slightly) less secure. +> +> If miners have a 5% orphan rate, then an attacker can launch a 51% attack +> with 49% of the network. +> +> It isn't a massive difference, but it is there. + +If miners aren't validating the blocks they mine on top of, an +attacker can do more nasty things I think. + +> As long as miners switch back to non-SPV mining after a timeout, SPV-mini= +ng +> is safe for everyone. +> +> The average cost to the miner from building on an invalid block is small,= + as +> long as invalid blocks only happen rarely. +> +> Miners still have an incentive to do full validation, so that they can +> include transactions and get transaction fees. +> +> SPV-mining is to prevent hashing hardware from having to waste power when= + it +> isn't needed. + +As long as miners switch back to the new longest chain after they +validate the block, mining on top of the +non-most-work-but-surely-valid may be less risky than mining on top of +a most-work-but-potentially-invalid block. +This has risks too. In both cases, if they don't mine a block during +the block validation, everything is fine. +If they successfully SPV mine, they risk having mined on top of an +invalid block, which not only means lost coins for them but high risk +for regular SPV users. +If they successfully mine on top of the previous block, they start a +mini-race that they can win or not, but the impact to regular SPV +users is much lower. +The later may be slightly less profitable, but I bet the difference is +negligible. It would be interesting to know if miners actually did +this numbers and how (in case their model is incomplete or flawed). + +It is important to note that while SPV mining requires you to produce +empty blocks, mining on the previous on top of the previous block +allows you to include transactions and earn fees. +In a future where block rewards aren't so overwhelmingly dominated by +subsidies, the numbers will run against SPV mining. +In a future without (or with negligible) subsidy, SPV mining is always +inferior to just keep mining on top of the same block you were mining +until you fully validate the next one. + +> It may be less of a problem if (when?) electricity costs dominate hardwar= +e +> capital costs. + +This seems correct (for both cases). +It's also less worrying the shorter the full validation time of a block is. + |