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 674AEE86 for ; Fri, 5 Feb 2016 09:58:39 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-vk0-f51.google.com (mail-vk0-f51.google.com [209.85.213.51]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id F08E4A7 for ; Fri, 5 Feb 2016 09:58:37 +0000 (UTC) Received: by mail-vk0-f51.google.com with SMTP id e6so53275546vkh.2 for ; Fri, 05 Feb 2016 01:58:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jtimon-cc.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=EQufEkkCZ2+6QLiPVia0quG2tfzJj+l4QHBwCe8qqho=; b=xXSiOmjlLEnYq2+mgwesv2VxzCzODGdcKRWoibkAXOtNWhAD7ljSY+6cC4FO+D/+AC 5sgl5ipGZUjktuuSaltz6KmMbWsnLpTZ25kWezjQefMwK+0DEZBCcNQYhBc3o9UwZGZk 7w8hdXrcSRsIGjp723OnRj8MpheF9KGXPYCFQCrgz38qNRpmHR1NhufjF+OjuCqswSYi CkwZjic9YbwmpjSAYLyAticlMWLH912mXsP/gDgg+5+V/45HOwxRU1JAtEaJ61882ZGK Xe6brUVjhFRxDwMfTho8jgwJJKTAcWVYqrOHx4YaV6BIHjDt3rEzUxjNQHFCaQd9NsqV fQEA== 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; bh=EQufEkkCZ2+6QLiPVia0quG2tfzJj+l4QHBwCe8qqho=; b=cCK9PrQdyqwvOCilym40vQ3bmFZB4hvRWXTGjo4eLoIa+ClWSZndTYxm0zjmxM3Q4Q fZXTjTXXj3wP4Mu7SgS4KirTMmMCg/ldzGFHB8W7aIovHHcnsr1o21OA7ozEyh1IJUDC an1M+29vnGnI+J/G3cdoUoFCwE8F/gSRFfYAtRJTNmRywuf4NiR2eoHBCbhvEIpkqYTI F4X1tbEllNcGDHuYiAb+8g7sk6LalmM+0sEfbQWacTOeQwbc0aGQqb2TDdLpt4xZzVjN uFUImCvnDEHEonh9QXz8w+e1tEyVfUDP6jyn3LDmuWMYcM0U07bv4J3f5XqwlaCLSMO3 /pgg== X-Gm-Message-State: AG10YOSPCj752NlhXBv1wMVhTEa24XR7Fa/lpozfgKtvDFR0yfyGnme0xD+OA/y6hcXLVOYaSggqiV9QuBMwvg== MIME-Version: 1.0 X-Received: by 10.31.14.195 with SMTP id 186mr8763556vko.2.1454666317076; Fri, 05 Feb 2016 01:58:37 -0800 (PST) Received: by 10.31.141.73 with HTTP; Fri, 5 Feb 2016 01:58:36 -0800 (PST) Received: by 10.31.141.73 with HTTP; Fri, 5 Feb 2016 01:58:36 -0800 (PST) In-Reply-To: References: Date: Fri, 5 Feb 2016 10:58:36 +0100 Message-ID: From: =?UTF-8?B?Sm9yZ2UgVGltw7Nu?= To: Gavin Andresen Content-Type: multipart/alternative; boundary=001a1143d31218af35052b02e5b0 X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HTML_MESSAGE,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] Hardfork bit BIP X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 05 Feb 2016 09:58:39 -0000 --001a1143d31218af35052b02e5b0 Content-Type: text/plain; charset=UTF-8 Concept ACK. I've been talking about adding this to BIP99 since before scaling bitcoin Hong Kong, so it will be nice to have a BIP to just point to. Also I hadn't thought about concurrent deployment of 2 hardforks, nice. On Feb 4, 2016 23:30, "Gavin Andresen via bitcoin-dev" < bitcoin-dev@lists.linuxfoundation.org> wrote: > If the worry is full nodes that are not upgraded, then a block with a negative version number will, indeed, fork them off the the chain, in exactly the same way a block with new hard-forking consensus rules would. And with the same consequences (if there is any hashpower not paying attention, then a worthless minority chain might continue on with the old rules). Additionally, a warning or special error could be thrown when a block is rejected due to the hardfork bit being activated. > I think a much better idea than this proposed BIP would be a BIP that recommends that SPV clients to pay attention to block version numbers in the headers that they download, and warn if there is a soft OR hard fork that they don't know about. Although I agree this PR should include such warning/error recommendations, SPV nodes can't tell whether a change is a hardfork or a softfork just by looking at the version bits, even in the case of uncontroversial hardforks deployed with bip9 as recommended by bip99. For controversial hardforks where bip9 should NOT be used for deployment, setting the hardfork bit is even more important. > It is also a very good idea for SPV clients to pay attention to timestamps in the block headers that the receive, and to warn if blocks were generated either much slower or faster than statistically likely. Doing that (as Bitcoin Core already does) will mitigate Sybil attacks in general. This seems out of the scope of this PR. --001a1143d31218af35052b02e5b0 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Concept ACK. I've been talking about adding this to BIP9= 9 since before scaling bitcoin Hong Kong, so it will be nice to have a BIP = to just point to. Also I hadn't thought about concurrent deployment of = 2 hardforks, nice.

On Feb 4, 2016 23:30, "Gavin Andresen via bitcoin-dev&q= uot; <bitcoin-d= ev@lists.linuxfoundation.org> wrote:

> If the worry is full nodes that are not upgraded, then = a block with a negative version number will, indeed, fork them off the the = chain, in exactly the same way a block with new hard-forking consensus rule= s would. And with the same consequences (if there is any hashpower not payi= ng attention, then a worthless minority chain might continue on with the ol= d rules).

Additionally, a warning or special error could be thrown whe= n a block is rejected due to the hardfork bit being activated.

> I think a much better idea than this proposed BIP would= be a BIP that recommends that SPV clients to pay attention to block versio= n numbers in the headers that they download, and warn if there is a soft OR= hard fork that they don't know about.

Although I agree this PR should include such warning/error r= ecommendations, SPV nodes can't tell whether a change is a hardfork or = a softfork just by looking at the version bits, even in the case of uncontr= oversial hardforks deployed with bip9 as recommended by bip99. For controve= rsial hardforks where bip9 should NOT be used for deployment, setting the h= ardfork bit is even more important.

> It is also a very good idea for SPV clients to pay atte= ntion to timestamps in the block headers that the receive, and to warn if b= locks were generated either much slower or faster than statistically likely= . Doing that (as Bitcoin Core already does) will mitigate Sybil attacks in = general.

This seems out of the scope of this PR.

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