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 D18C61BA9 for ; Tue, 29 Sep 2015 19:54:50 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mx1.riseup.net (mx1.riseup.net [198.252.153.129]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 3194B189 for ; Tue, 29 Sep 2015 19:54:50 +0000 (UTC) Received: from cotinga.riseup.net (unknown [10.0.1.161]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (Client CN "*.riseup.net", Issuer "COMODO RSA Domain Validation Secure Server CA" (verified OK)) by mx1.riseup.net (Postfix) with ESMTPS id A19B0C2C63; Tue, 29 Sep 2015 12:54:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=riseup.net; s=squak; t=1443556489; bh=hg73ot+XfiXcOx3xSksFnKbFWMdXPBywjr4fy8yCr6M=; h=Date:From:To:CC:Subject:References:In-Reply-To:From; b=P6nlojxcG0uPNLo/xA0CaXIj06gr9S8FYQZAl1s7hCLxDIYHIKOMlPcfDbKhBWlMo Y192N7CoNFwp/iSbfwRGfyjeo+geWlmrQYVAGh3vlYTdNhMbs3Mg8V/3wzCgFFcWcl IA1GiqB7dyCcWTek/ul0Aoai4ha5Z1HsbA0N2mJ0= Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: odinn.cyberguerrilla) with ESMTPSA id 2D81A1C0226 Message-ID: <560AEC81.8040903@riseup.net> Date: Tue, 29 Sep 2015 19:54:41 +0000 From: odinn MIME-Version: 1.0 To: jl2012@xbt.hk, "Jonathan Toomim (Toomim Bros)" References: <20150927185031.GA20599@savin.petertodd.org> <20150928132127.GA4829@savin.petertodd.org> <20150928142953.GC21815@savin.petertodd.org> <20150928144318.GA28939@savin.petertodd.org> <40B097BA-A389-4C46-B5DE-2EC4738086BA@toom.im> <5e90be1b8f85cd46ed20eae84c062702@xbt.hk> In-Reply-To: <5e90be1b8f85cd46ed20eae84c062702@xbt.hk> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Virus-Scanned: clamav-milter 0.98.7 at mx1.riseup.net X-Virus-Status: Clean X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_LOW,T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY 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] Let's deploy BIP65 CHECKLOCKTIMEVERIFY! 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 Sep 2015 19:54:50 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 Hello, (see my remarks below) jl2012 via bitcoin-dev: > Jonathan Toomim (Toomim Bros) via bitcoin-dev 於 2015-09-29 09:30 寫 > 到: >> SPV clients will appear to behave normally, and will continue to >> show new transactions and get confirmations in a timely fashion. >> However, they will be systematically susceptible to attack from >> double-spends that attempt to spend funds in a way that the >> upgraded nodes will reject. These transactions will appear to >> get 1 confirmation, then regress to zero conf, every single time. >> These attacks can be performed for as long as someone mines with >> the old version. > > 1. Who told you to accept 1-confirmation tx? Satoshi recommended 6 > confirmations in the whitepaper. Take your own risk if you do not > follow his advice. > > 2. This is true only if your SPV client naively follows the > longest chain without even looking at the block version. This might > be good enough for the 1st generation SPV client, but future > generations should at least have basic fraud detecting mechanism. > > Regarding "basic fraud detecting mechanism" of which you speak, being as I personally enjoy SPV for the time being (Electrum), and I know that people will continue to keep using SPV wallets because they are light and handy, I think that you make a good point that "basic fraud detecting mechanism" is needed, but how to verify that such a mechanism in an SPV wallet is good, and/or that the software and version information provided by the server admins via the banner is valid (being as it's not validated)? I have made a thread on this conundrum. Which is posted here if you are interested. https://bitcointalk.org/index.php?topic=1157545.0 So as to avoid repeating stuff please read whole thead before answering in it or posting back to list. It seems that there are definitely unanswered questions... I may open this up as an issue on https://github.com/spesmilo/electrum about this stuff, but I wanted to post comment here also, for the record . > >> If an attacker thinks he could get more than 25 BTC of >> double-spends per block, he might even choose to mine with the >> obsolete version in order to get predictable orphans and to trick >> SPV clients and fully verifying wallets on the old version. > > This point is totally irrelevant. No matter there is a softfork or > not, SPV users are always vulnerable to such double-spending attack > if they blindly follow the longest chain AND accept 1-confirmation. > The fiat currency system might be safer for them. > _______________________________________________ bitcoin-dev mailing > list bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev - -- http://abis.io ~ "a protocol concept to enable decentralization and expansion of a giving economy, and a new social good" https://keybase.io/odinn -----BEGIN PGP SIGNATURE----- iQEcBAEBCgAGBQJWCuyBAAoJEGxwq/inSG8CtpAH/R6N1QYzMFWPo75RsP46VYbi k33QbsbhlEznEEWX/ayKEzmnbt7DkXFXQtesuabongFr9UpwxED0OGQJztyRz5NC iS8ty+Kfi9/Aq/e79A6IPSYfRCPB1w+oP/cEsV/LB4BPkut2mdpMbdwDZ3TQuLRq LnFLmz8tY+CUqSbyrPUx/FKJ7ZbQsAlammMTKoUYaAYRytDBPzW4PdYtTyrK2QTK jjt11n5U8ShmXdsCo/E0pWVbggQlhFgrCoIYjGNfmDyK/eYaskD5O6czIdqd5WPs P+2zMC1Cukkr5l8BQXiSedVXGpMyaYhMgWB7MD6sNDIAE9IFbfEpkse/Ek4aJII= =Ud4C -----END PGP SIGNATURE-----