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 DF237A87 for ; Fri, 2 Dec 2016 01:42:48 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ua0-f178.google.com (mail-ua0-f178.google.com [209.85.217.178]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 6239E167 for ; Fri, 2 Dec 2016 01:42:48 +0000 (UTC) Received: by mail-ua0-f178.google.com with SMTP id 51so267387092uai.1 for ; Thu, 01 Dec 2016 17:42:48 -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:from:date:message-id:subject:to; bh=qiiVkkkqFXyMnHTuXuwcPLKcKVB0AvKCWApO2FCSEr4=; b=1n4d3w9zXTgoG4fQUgsmmijWD74SkZEKhBDzx+2r3dDl9ys0Qo/NL+CXzhPG85mTEg byKQY0mon/80jb+5hafYlDBP1UCEaM6boaF0CYrfdU2XdrH8SiLrL96X0Q5TD463k0n6 Mwjan6ru5CwF5/nUZgxfi0qsvA//HV4014KVp7gmrhvVMSVomS5zMUHXQP6sDmX4tU3o RMPjeayQcaVnMIRSvfukHJn/rjvCnW8fXEL/MprTJ/zvJmIXUQPvLslbBaCnhEn085oT 6/khKYW+mFQT4O0xxwVCXF7s6VJNRBdXgCICe8SCj8Wx/Bt7+aXtmMWS50av+Qzw1C0d EV3Q== 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:from:date :message-id:subject:to; bh=qiiVkkkqFXyMnHTuXuwcPLKcKVB0AvKCWApO2FCSEr4=; b=WfAwXGPFLopsznM8kyI0/UXTIJ1Hh2tjfwwNaXFyXLH4iv+U7WbEueaBBudjRvrute KYDIG1ZhyxaPaQEW573gbKD+c4jxWRSUj5AXK4CX4z0dzWfH/pcCO3GCjW5URLYUJLPO HUgHICwqWod/cu+IuGjeZMVkYR6tWKqixn7APd09+Yyts0Jr4CkPqlYt3hwvJEzrg8M4 LQJHQbNQeLZmLO8MYs9Kex5/WG8s0Dy7kI/Nd8oUGLKaRD9XKoeeV7fbWNqZn7OgfYxZ zLa+xTpViZfYIRSTLuydOjoHxqvvSgXn77J4MEbP2AbFr7n3aLbyGXu6UKXUumyljwQt 24Mw== X-Gm-Message-State: AKaTC00evSVKUXRW07ZMR/20YU2pZGrnW8Vwu15432LgoYOaTHdExhoe3OV050N6/JMy8Re/iTjZ4stEMWBDmA== X-Received: by 10.159.48.65 with SMTP id i1mr30597262uab.12.1480642967532; Thu, 01 Dec 2016 17:42:47 -0800 (PST) MIME-Version: 1.0 Received: by 10.31.137.20 with HTTP; Thu, 1 Dec 2016 17:42:46 -0800 (PST) In-Reply-To: <08F5E788-8680-4BBE-8871-73FF022C52DB@xbt.hk> References: <08F5E788-8680-4BBE-8871-73FF022C52DB@xbt.hk> From: =?UTF-8?B?Sm9yZ2UgVGltw7Nu?= Date: Fri, 2 Dec 2016 02:42:46 +0100 Message-ID: To: Johnson Lau , Bitcoin Protocol Discussion Content-Type: text/plain; charset=UTF-8 X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, 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] New BIP: Hardfork warning system 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: Fri, 02 Dec 2016 01:42:49 -0000 We can already warn users of a hardfork when a block is invalid (at least) because of the highest bit in nVersion (as you say, because it is forbidden since bip34 was deployed). It seems the softfork serves only to warn about soft-hardforks, assuming it chooses to use this mechanism (which a malicious soft hardfork may not do). In fact, you could reuse another of the prohibited bits to signal a soft-hardfork while distinguishing it from a regular hardfork. And this will also serve for old nodes that have not upgraded to the softfork. But, wait, if you signal a soft-hardfork with an invalid bit, it's not a soft-hardfork anymore, is it? It's simply a hardfork. Your softfork would result in soft hardforks being hardforks for nodes that upgraded to this softfork, but softforks for older nodes. Is this the intended behaviour? if so, why? I would rather have a simpler BIP that doesn't require a softfork (whether it recommends soft-hardforks to use one of the currently invalid bits, but a different one than from hardforks or not, but I also don't see the reason why soft-hardforks should appear as invalid blocks for older nodes instead of using regular softfork warning [besides, in this case, after the "unkown softfork" warning you will get only empty blocks, which may make you suspicious]).