Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id E2F4BBAD for ; Mon, 18 Dec 2017 21:51:42 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ua0-f169.google.com (mail-ua0-f169.google.com [209.85.217.169]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 3959B1A6 for ; Mon, 18 Dec 2017 21:51:42 +0000 (UTC) Received: by mail-ua0-f169.google.com with SMTP id i4so11676406uab.5 for ; Mon, 18 Dec 2017 13:51:42 -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 :cc; bh=7iHHYqprp3c9kF9YqusoqXZlHORq2Q6Ww1x3J0AHdNE=; b=QYz8g8RIFFADkwkl88EZG5yjwFyONRcvU0t3tfQHL3QGrNhK20q2GbmQHxrVUziJcy yDe3A4gBLMfqgW8QWtweeq8eOmyE3OTAk608ncx3f9PqpX0rlyyMJd7xuWzofm+MCLdL WqfrIjuBiWjgglQdELl1t7bv3RHazGos7zTTvamJZKTmOGq5PBz9mf/agVZ6y7jsHNwx Kf9jWW+GW3IE0bHwQkMaf024Sr3DR9Lv7e+ldme3/RMgiOQK0FvLp/vwJHspIeRTintw bHfhqYMrwazVO166N8AtD/+My9VcMNnFtpBp7bgx7cJvBxA5zAhoSd2NDzv+U61WyvJX Hq/w== 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:cc; bh=7iHHYqprp3c9kF9YqusoqXZlHORq2Q6Ww1x3J0AHdNE=; b=hsHdNh4HRuU4J8HCl2Oaw113uTslsysEiRiJ0RlCRG+ObGvbCzZ388MS6BGMYPZ2Cd jGHEnQI0ln8uicTEV9QaPviUblg73Z9FYyA2X51hLVtX6py/2D7PRfbV/2MjHgwu3JAM nM0c71qCzyI/MEbSARb9reXTKhm5WIO1BTtPy4flC+oswkktZYfyXfEQNiutYSjFP15z PdjTn/lurmZN9XPOXCPN5dnU0JCzq4Bli/qpkPLPcpbyhGZR346rmfhYBpvsTiJaeWIB 2HTjL+Xry5Hs4Im8kXH6eD6TTrKfPBT1yfUEGvtIE83emzkxvYmOh7X7eYtK3iH5PuEM HQ7g== X-Gm-Message-State: AKGB3mLgn46oMuUEV20CON7WLh3hzIK6dKkdVi9D7SoJVyvh5bWYAA7Q wnmiH79a4olvu70lr2SlJxU4yHcMjPE4zR5+KolP4nGb X-Google-Smtp-Source: ACJfBoskdG1jsepRMpVF62RER6Uhu8urkvgMYmGRnAGiq2J7Fg9pufb1gNvXMnxJ64JqcZT4OmIL3CwbXHRB6SsXzWo= X-Received: by 10.176.81.233 with SMTP id h38mr1381183uaa.46.1513633901343; Mon, 18 Dec 2017 13:51:41 -0800 (PST) MIME-Version: 1.0 Received: by 10.176.30.138 with HTTP; Mon, 18 Dec 2017 13:51:40 -0800 (PST) In-Reply-To: References: From: Kalle Rosenbaum Date: Mon, 18 Dec 2017 22:51:40 +0100 Message-ID: To: Gregory Maxwell Content-Type: multipart/alternative; boundary="94eb2c19215e02814f0560a45b5d" 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 22:14:12 +0000 Cc: Bitcoin Protocol Discussion 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 21:51:43 -0000 --94eb2c19215e02814f0560a45b5d Content-Type: text/plain; charset="UTF-8" Hi Greg, 2017-12-18 21:42 GMT+01:00 Gregory Maxwell : > Because it would make no meaningful difference now, Sure. > and if you are not > going to check the history I'm not going to do any less checks than a node running with assumevalid. Well not exactly true, because a node running today with assumevalid will verify the witness root hash, right? > there are much more efficient things to > do-- like not transfer it at all. > I'm not sure what you are referring to. Thank you /Kalle > > On Mon, Dec 18, 2017 at 8:32 AM, Kalle Rosenbaum via bitcoin-dev > 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. 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 > > > --94eb2c19215e02814f0560a45b5d Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi G= reg,

2= 017-12-18 21:42 GMT+01:00 Gregory Maxwell <greg@xiph.org>:
Because it would make no meaningful difference= now,

Sure.
=C2=A0
and if you are not
going to check the history

I'm not goin= g to do any less checks than a node running with assumevalid. Well not exac= tly true, because a node running today with assumevalid will verify the wit= ness root hash, right?
=C2=A0
there are much more efficient things to
do-- like not transfer it at all.

I'= ;m not sure what you are referring to.

Thank you
/Kalle
=C2=A0

On Mon, Dec 18, 2017 at 8:32 AM, 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. If my full node skips signature verification for<= br> > 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@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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