Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id DBCA2BE4 for ; Mon, 18 Dec 2017 13:35:46 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ua0-f173.google.com (mail-ua0-f173.google.com [209.85.217.173]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id E48C81A6 for ; Mon, 18 Dec 2017 13:35:45 +0000 (UTC) Received: by mail-ua0-f173.google.com with SMTP id l36so10651987uae.4 for ; Mon, 18 Dec 2017 05:35:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rosenbaum-se.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=ezgU3v8LDwE/1XszAi0WjpqRFndHLURpZm0Ivlfxuh0=; b=PB8SoKL4kZBedwkG+MIObWFgsnMUXC12qkd+paxxJOK46N+5XWV7PdQqmrQDNEDaji szeVsISzfnAhOzQqHtP0AZdvTGnsoi7ipir0q44ykRyUHXOsGmYgJgIL/WPt3OieROPa 4qP2xcBpASVE67O0tbPLBtDHNt5mR8hMVsL1z1Zg71zEmA0cv3pnkDfSr1fVqRW0HnmE gHlvUoH4iwwJ7L/5iAqUbIs7W27mGNk/tyGratLVs7KJc+nGrHPJes0O3WDemYp+ROnS M25Tlc3ubZWTIBfCg04rzoQtVo9IkpJXhcBrH2VHbvIgZ8lgTrD2lLBt/wyx7zmI3Ym2 HXRA== 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=ezgU3v8LDwE/1XszAi0WjpqRFndHLURpZm0Ivlfxuh0=; b=SnQKVqUyFW8ysAuvikSJrntZ5GoegXcehSrX7ipOIp0Tr7eWwDWiGgrlcpIIAgeaP2 vrfcc765SPSEEmvpwppjzSf9lJrNtadhC8laq1AtxbYjIRPjO4vXzVZ+/utUN8TTg9ni dZXFMZuYOhgVDzbg+Eopf6zM+veW19Yap5Xn+a64UXMkjZuUH7z6lXkoIBUOTjZ5fXX/ l9cZpDFOOJKBN1XJ/znbj4d2ROLuIrib/75jFXd1kSX5+vuMdhqAvjMC7nwmTiHECyjq FKGtnnmJ327AAWe+Y7aM3zuIdbQVDT6IpBhmQ++QejqjvZ61VKnbdD1GN+014LE5uHQm F0Zg== X-Gm-Message-State: AKGB3mKG8uqGazt4RZsmS8TbGu8Vkxf0et9KkuVTG9YWlUZJE4q2xOG3 p4mAeibkItDM79p4zbZwritDMhjulTa7FxjwzVhIFuZAa0g= X-Google-Smtp-Source: ACJfBouuREpEKhtPvuG8FbFK9Lmt60GvZpITwazV+gJBChpYw3ppenq87gl8K+EcOSLechprstgWA952mnlotsfPynQ= X-Received: by 10.176.81.233 with SMTP id h38mr8086950uaa.46.1513604144997; Mon, 18 Dec 2017 05:35:44 -0800 (PST) MIME-Version: 1.0 Received: by 10.176.30.138 with HTTP; Mon, 18 Dec 2017 05:35:44 -0800 (PST) In-Reply-To: References: From: Kalle Rosenbaum Date: Mon, 18 Dec 2017 14:35:44 +0100 Message-ID: To: Eric Voskuil , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary="94eb2c19215e64b70005609d6d6f" 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 13:58:22 +0000 Subject: Re: [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 13:35:47 -0000 --94eb2c19215e64b70005609d6d6f Content-Type: text/plain; charset="UTF-8" 2017-12-18 13:43 GMT+01:00 Eric Voskuil : > > > On Dec 18, 2017, at 03:32, Kalle Rosenbaum via bitcoin-dev < > bitcoin-dev@lists.linuxfoundation.org> wrote: > > > > 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. > > Why run a full node if you are not going to verify the chain? > I meant to say "I find it hard to understand why a full node that does initial block download also must download witnesses when it is going to skip verification of the witnesses anyway." I'm referring to the "assumevalid" feature of Bitcoin Core that skips signature verification up to block X. Or have I misunderstood assumevalid? /Kalle > > > 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 > > _______________________________________________ > > bitcoin-dev mailing list > > bitcoin-dev@lists.linuxfoundation.org > > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > --94eb2c19215e64b70005609d6d6f Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
2017= -12-18 13:43 GMT+01:00 Eric Voskuil <eric@voskuil.org>:

> On Dec 18, 2017, at 03:32, Kalle Rosenbaum via bitcoin-dev <bitcoin-dev@lists.li= nuxfoundation.org> wrote:
>
> 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 verifi= cation anyway.

Why run a full node if you are not going to verify the chain?

I meant to say "I find it hard to understand why a full node that do= es initial block
download also must downlo= ad witnesses when it is going to skip verification of the witnesses anyway.= "

I'm referring to the "= assumevalid" feature of Bitcoin Core that skips signature verification= up to block X. Or have I misunderstood assumevalid?

/Kalle
=C2=A0

> 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 beca= use
> a bad peer may send me invalid witnesses during initial block
> download, and if I don't verify that the witness root hash actuall= y
> 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 abo= ut)
> 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<= br> > parts?
>
> So basically, what are the reasons not to implement witnessless
> nodes?
>
> Thank you,
> /Kalle
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@l= ists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev

--94eb2c19215e64b70005609d6d6f--