Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 715C3106C for ; Tue, 29 Dec 2015 07:47:24 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from s47.web-hosting.com (s47.web-hosting.com [199.188.200.16]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id D327789 for ; Tue, 29 Dec 2015 07:47:23 +0000 (UTC) Received: from [::1] (port=55558 helo=server47.web-hosting.com) by server47.web-hosting.com with esmtpa (Exim 4.86) (envelope-from ) id 1aDp06-002WsQ-J5; Tue, 29 Dec 2015 02:47:22 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Tue, 29 Dec 2015 02:47:22 -0500 From: jl2012 To: Peter Todd In-Reply-To: <20151229053559.GA8657@muck> References: <20151229053559.GA8657@muck> Message-ID: <26ec8367f2a1cda066b19e0bff498711@xbt.hk> X-Sender: jl2012@xbt.hk User-Agent: Roundcube Webmail/1.0.6 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - server47.web-hosting.com X-AntiAbuse: Original Domain - lists.linuxfoundation.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - xbt.hk X-Get-Message-Sender-Via: server47.web-hosting.com: authenticated_id: jl2012@xbt.hk X-Authenticated-Sender: server47.web-hosting.com: jl2012@xbt.hk X-Source: X-Source-Args: X-Source-Dir: X-From-Rewrite: unmodified, already matched X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,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] We can trivially fix quadratic CHECKSIG with a simple soft-fork modifying just SignatureHash() 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: Tue, 29 Dec 2015 07:47:24 -0000 Do we need to consider that someone may have a timelocked big tx, with private key lost? I think we need to tell people not to do this. Related discussion: https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-November/011656.html Peter Todd via bitcoin-dev 於 2015-12-29 00:35 寫到: > Occured to me that this hasn't been mentioned before... > > We can trivially fix the quadratic CHECK(MULTI)SIG execution time issue > by soft-forking in a limitation on just SignatureHash() to only return > true if the tx size is <100KB. (or whatever limit makes sense) > > This fix has the advantage over schemes that limit all txs, or try to > count sigops, of being trivial to implement, while still allowing for a > future CHECKSIG2 soft-fork that properly fixes the quadratic hashing > issue; >100KB txs would still be technically allowed, it's just that > (for now) there'd be no way for them to spend coins that are > cryptographically secured. > > For example, if we had an issue with a major miner exploiting > slow-to-propagate blocks(1) to harm their competitors, this simple fix > could be deployed as a soft-fork in a matter of days, stopping the > attack quickly. > > 1) > www.mail-archive.com/bitcoin-development@lists.sourceforge.net/msg03200.html > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev