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 98895B5D for ; Wed, 22 Mar 2017 20:49:09 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-it0-f46.google.com (mail-it0-f46.google.com [209.85.214.46]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 25619110 for ; Wed, 22 Mar 2017 20:49:09 +0000 (UTC) Received: by mail-it0-f46.google.com with SMTP id 190so30183021itm.0 for ; Wed, 22 Mar 2017 13:49:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bittorrent-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=IDrkOjJV3gjfBUDQkWOMa4jkOKEV4CpW18MiJMFq5hc=; b=IIOcvDEJKowfd+vnuKdJs5ca40der6vBNZVoRX/UGiGaD4KuKKReb6Lkc05tYPiUNT fAmeQ+9kW+E0VhnNqQeppkOAF/ZYzEoUHHG+cuWGZWy+fUs7X/JCEvGu48Ungb9ypFcM 69/cNf6tXALDGpQL2rsveIBh1eze2tX33nN/TAeJ4oMLk8jBW0faQM11S8YVb3gFKXtU 9L5YWI2KS/C4f7/GNFd3nSlYKFJR+aPk0QUkU/HGWrGX5arnPsV1C2Ia4eZfx1HA4LJK lK5CsyXRDh7TLDIXWal37NcYW3XZ2P/8tMqfyWr4HVvOoQvap7zj4k9YTBPFEDzCcRPy yr+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=IDrkOjJV3gjfBUDQkWOMa4jkOKEV4CpW18MiJMFq5hc=; b=g62dnIKWbJw8kDZSLSYykP1/bzIwQHjUSMu5bla8lvHJlbyzXGvclmUvZDzHRIx7a0 L73fnUxnjcHAxgwQRVAVoDqp/cZlGDYq5Ri0NDBC5EmCp5sIlzw9KhnxqKzH0HuZr0Uk ehYx3vmlHu3IityGCJu3blaclN61b6/9kp3O28yC0amjzVdscQMn9+2NtwdWGoJvZ2y6 cwF5LpcP+7aePFViYTMzWDTKD2w+xdjQIEqXTFVnfoKN9MMeQvDWulhKpsynwKCJlRfk J9SVzfcpQNSuVK4LoNT0c+ccIUqNNsMpTJ03ujYpfY68ThBk2/yO7nWWiBZ4tRbotocc /sUw== X-Gm-Message-State: AFeK/H32yhp9CkDmYD/Y7gL1u0+HYKmHVQ3kst3lSagHKS/lJrccNRck3HwniWmZagsMh0HqIVdpqUAdsd0GgLLg X-Received: by 10.36.86.83 with SMTP id o80mr10272950itb.65.1490215748540; Wed, 22 Mar 2017 13:49:08 -0700 (PDT) MIME-Version: 1.0 Received: by 10.36.254.132 with HTTP; Wed, 22 Mar 2017 13:49:08 -0700 (PDT) In-Reply-To: <201703220847.31303.luke@dashjr.org> References: <201703220847.31303.luke@dashjr.org> From: Bram Cohen Date: Wed, 22 Mar 2017 13:49:08 -0700 Message-ID: To: Luke Dashjr , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary=001a1140464454af5a054b57e42c X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HTML_MESSAGE, RCVD_IN_DNSWL_NONE, RCVD_IN_SORBS_SPAM 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] Fraud proofs for block size/weight 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: Wed, 22 Mar 2017 20:49:09 -0000 --001a1140464454af5a054b57e42c Content-Type: text/plain; charset=UTF-8 Some questions: Does this require information to be added to blocks, or can it work today on the existing format? Does this count number of transactions or their total length? The block limit is in bytes rather than number of transactions, but transaction number can be a reasonable proxy if you allow for some false negatives but want a basic sanity check. Does this allow for proofs of length in the positive direction, demonstrating that a block is good, or does it only serve to show that blocks are bad? Ideally we'd like an extension to SPV protocol so light clients require proofs of blocks not being too big, given the credible threat of there being an extremely large-scale attack on the network of that form. On Wed, Mar 22, 2017 at 1:47 AM, Luke Dashjr via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > Despite the generalised case of fraud proofs being likely impossible, there > have recently been regular active proposals of miners attacking with simply > oversized blocks in an attempt to force a hardfork. This specific attack > can > be proven, and reliably so, since the proof cannot be broken without also > breaking their attempted hardfork at the same time. > > While ideally all users ought to use their own full node for validation > (even > when using a light client for their wallet), many bitcoin holders still do > not. As such, they are likely to need protection from these attacks, to > ensure > they remain on the Bitcoin blockchain. > > I've written up a draft BIP for fraud proofs and how light clients can > detect > blockchains that are simply invalid due to excess size and/or weight: > > https://github.com/luke-jr/bips/blob/bip-sizefp/bip-sizefp.mediawiki > > I believe this draft is probably ready for implementation already, but if > anyone has any idea on how it might first be improved, please feel free to > make suggestions. > > Luke > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > --001a1140464454af5a054b57e42c Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Some questions:

Does this require infor= mation to be added to blocks, or can it work today on the existing format?<= /div>

Does this count number of transactions or their to= tal length? The block limit is in bytes rather than number of transactions,= but transaction number can be a reasonable proxy if you allow for some fal= se negatives but want a basic sanity check.

Does t= his allow for proofs of length in the positive direction, demonstrating tha= t a block is good, or does it only serve to show that blocks are bad? Ideal= ly we'd like an extension to SPV protocol so light clients require proo= fs of blocks not being too big, given the credible threat of there being an= extremely large-scale attack on the network of that form.


On Wed,= Mar 22, 2017 at 1:47 AM, Luke Dashjr via bitcoin-dev <= ;bitcoin-dev@lists.linuxfoundation.org> wrote:
Despite the generalised case of fraud proofs being like= ly impossible, there
have recently been regular active proposals of miners attacking with simply=
oversized blocks in an attempt to force a hardfork. This specific attack ca= n
be proven, and reliably so, since the proof cannot be broken without also breaking their attempted hardfork at the same time.

While ideally all users ought to use their own full node for validation (ev= en
when using a light client for their wallet), many bitcoin holders still do<= br> not. As such, they are likely to need protection from these attacks, to ens= ure
they remain on the Bitcoin blockchain.

I've written up a draft BIP for fraud proofs and how light clients can = detect
blockchains that are simply invalid due to excess size and/or weight:

=C2=A0 =C2=A0 https://github.com= /luke-jr/bips/blob/bip-sizefp/bip-sizefp.mediawiki

I believe this draft is probably ready for implementation already, but if anyone has any idea on how it might first be improved, please feel free to<= br> make suggestions.

Luke
_______________________________________________
bitcoin-dev mailing list
bitcoin-dev@lists.= linuxfoundation.org
https://lists.linuxfoundation.org= /mailman/listinfo/bitcoin-dev

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