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 D50768D9 for ; Mon, 18 Dec 2017 08:32:25 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ua0-f182.google.com (mail-ua0-f182.google.com [209.85.217.182]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 3D0EFFE for ; Mon, 18 Dec 2017 08:32:25 +0000 (UTC) Received: by mail-ua0-f182.google.com with SMTP id p33so10108810uag.9 for ; Mon, 18 Dec 2017 00:32:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rosenbaum-se.20150623.gappssmtp.com; s=20150623; h=mime-version:from:date:message-id:subject:to; bh=kp0bAYpThKPDtZsgLpkvSphPynouGTONmQA9HRFvLIQ=; b=Mr+HJWjXq/yOr5kNtXY3BR3dh8Y5uUxa4fD71TaZ7Lezfxa1Tde1AsyozW37q9Ew1U VM5rshAnoE/tO/RfM8vo29BRXglZhelMKaxiH55OqaLGegKerPlqYtFZ90o1h3zyixNI d77zBds7vt0oJMbOlMgSs62nE36PtcjpTs6Bc+qOtwDvkfsDwnyvYup4lALpgOGgG0yU H4yMeD71wNJgHZSEJX38plIupB8f5q5/4kuyQ8MvIntzj2uhsbxf+1NfCCw4DKfqFRHw KGDoH6+j+iOwVe5/mGodkgQsSet2Mm4928UREYTL5Pz1J4sMNsbKF06tQzuKK4bRDdtI iSFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=kp0bAYpThKPDtZsgLpkvSphPynouGTONmQA9HRFvLIQ=; b=KdpnzQpqKyjIoZOgEXkhZWDjJ4G/9p0Q9ep4xJkYlszazBI6hPCp4BRoWwAelutDIl G+r6w4QsPimw0vLynclU8O79sdAfb4iGwz9uSg09V0HkAuixwwHAk9tOKnPJ3VanSqaq cl4atmgtl1kXtPASRb7on7+ENrs5ATMG312ot/l7VsXpWN1Nujj8TjEIG3NnJVm2tQ75 4ZqFR6HAibGf+VTQWWoIKpdmJ/gTWfg78sTuBSQZgeXwGaOAA010FU7LMx7OMaPr3k1O B3+I89c3l/3cAqwtpztZj/P/xvtfQP/eTxQzU139WYqU8oyk06Hpl2fQuPatvWxd/8+V KmRg== X-Gm-Message-State: AKGB3mKm/b34ywY1ITXqV7LKOIVkq9pdEYnTTX46vetFnvkvMj/NCrmp Mne/WIVpSM1Cj1uk1B9gITjlDPEfT4bI4KPFbcaswuaAPfg= X-Google-Smtp-Source: ACJfBovN9+chOxkIzDBF4KHlTbMZMdno5xHUtiP0tNRkgglcyqmRD9q9DVD1F47P1i4M/Msu+KNILfIBmZWGOQVxNQo= X-Received: by 10.159.35.161 with SMTP id 30mr23483986uao.44.1513585943945; Mon, 18 Dec 2017 00:32:23 -0800 (PST) MIME-Version: 1.0 Received: by 10.176.30.138 with HTTP; Mon, 18 Dec 2017 00:32:23 -0800 (PST) From: Kalle Rosenbaum Date: Mon, 18 Dec 2017 09:32:23 +0100 Message-ID: To: bitcoin-dev Content-Type: multipart/alternative; boundary="94eb2c04063286bbce05609930ef" X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HTML_MESSAGE, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Mon, 18 Dec 2017 11:55:15 +0000 Subject: [bitcoin-dev] Why not witnessless nodes? 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: Mon, 18 Dec 2017 08:32:26 -0000 --94eb2c04063286bbce05609930ef Content-Type: text/plain; charset="UTF-8" Dear list, I find it hard to understand why a full node that does initial block download also must download witnesses if they are going to skip verification anyway. If my full node skips signature verification for blocks earlier than X, it seems the reasons for downloading the witnesses for those blocks are: * to be able to send witnesses to other nodes. * to verify the witness root hash of the blocks I suppose that it's important to verify the witness root hash because a bad peer may send me invalid witnesses during initial block download, and if I don't verify that the witness root hash actually commits to them, I will get banned by peers requesting the blocks from me because I send them garbage. So both the reasons above (there may be more that I don't know about) are actually the same reason: To be able to send witnesses to others without getting banned. What if a node could chose not to download witnesses and thus chose to send only witnessless blocks to peers. Let's call these nodes witnessless nodes. Note that witnessless nodes are only witnessless for blocks up to X. Everything after X is fully verified. Witnessless nodes would be able to sync faster because it needs to download less data to calculate their UTXO set. They would therefore more quickly be able to provide full service to SPV wallets and its local wallets as well as serving blocks to other witnessless nodes with same or higher assumevalid block. For witnessless nodes with lower assumevalid they can serve at least some blocks. It could also serve blocks to non-segwit nodes. Do witnessless nodes risk dividing the network in two parts, one witnessless and one with full nodes, with few connections between the parts? So basically, what are the reasons not to implement witnessless nodes? Thank you, /Kalle --94eb2c04063286bbce05609930ef Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Dear list,

I find it hard to= understand why a full node that does initial block
download also= must download witnesses if they are going to skip
verification a= nyway. If my full node skips signature verification for
blocks ea= rlier than X, it seems the reasons for downloading the
witnesses = for those blocks are:

* to be able to send witness= es to other nodes.

* to verify the witness root ha= sh of the blocks

I suppose that it's important= to verify the witness root hash because
a bad peer may send me i= nvalid witnesses during initial block
download, and if I don'= t verify that the witness root hash actually
commits to them, I w= ill get banned by peers requesting the blocks from
me because I s= end them garbage.

So both the reasons above (there= may be more that I don't know about)
are actually the same r= eason: To be able to send witnesses to others
without getting ban= ned.

What if a node could chose not to download wi= tnesses and thus chose to
send only witnessless blocks to peers. = Let's call these nodes
witnessless nodes. Note that witnessle= ss nodes are only witnessless
for blocks up to X. Everything afte= r X is fully verified.

Witnessless nodes would be = able to sync faster because it needs to
download less data to cal= culate their UTXO set. They would therefore
more quickly be able = to provide full service to SPV wallets and its
local wallets as w= ell as serving blocks to other witnessless nodes
with same or hig= her assumevalid block. For witnessless nodes with
lower assumeval= id they can serve at least some blocks. It could also
serve block= s to non-segwit nodes.

Do witnessless nodes risk d= ividing the network in two parts, one
witnessless and one with fu= ll nodes, with few connections between the
parts?

<= /div>
So basically, what are the reasons not to implement witnessless
nodes?

Thank you,
/Kalle
<= /div> --94eb2c04063286bbce05609930ef--