Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1WcvWa-0005yB-P6 for bitcoin-development@lists.sourceforge.net; Wed, 23 Apr 2014 11:39:36 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of gmail.com designates 74.125.82.171 as permitted sender) client-ip=74.125.82.171; envelope-from=andyparkins@gmail.com; helo=mail-we0-f171.google.com; Received: from mail-we0-f171.google.com ([74.125.82.171]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WcvWa-0005Bm-0Q for bitcoin-development@lists.sourceforge.net; Wed, 23 Apr 2014 11:39:36 +0000 Received: by mail-we0-f171.google.com with SMTP id t61so720155wes.2 for ; Wed, 23 Apr 2014 04:39:29 -0700 (PDT) X-Received: by 10.194.201.73 with SMTP id jy9mr1999473wjc.51.1398253169828; Wed, 23 Apr 2014 04:39:29 -0700 (PDT) Received: from grissom.localnet ([91.84.15.31]) by mx.google.com with ESMTPSA id j3sm1128391wjw.38.2014.04.23.04.39.28 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 23 Apr 2014 04:39:29 -0700 (PDT) From: Andy Parkins To: Mike Hearn Date: Wed, 23 Apr 2014 12:39:18 +0100 User-Agent: KMail/1.13.7 (Linux/3.2.0-1-686-pae; KDE/4.8.4; i686; ; ) References: <201404231057.54387.andyparkins@gmail.com> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Message-Id: <201404231239.20202.andyparkins@gmail.com> X-Spam-Score: -1.6 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (andyparkins[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1WcvWa-0005Bm-0Q Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Coinbase reallocation to discourage Finney attacks X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Apr 2014 11:39:37 -0000 On Wednesday 23 Apr 2014 12:07:25 Mike Hearn wrote: > > Just pedantry: 100% of credit card transactions _can_ be fradulantly > > charged > > back but arent. > > If you do a chargeback the bank double checks this, investigates it and > people who repeatedly try and do fraudulent chargebacks get their > accounts terminated. It's not like your bank offers you a "reverse this > payment" button in the UI that always works, right? True; the effort of a chargeback is non-zero on credit cards; but that's my point: it's non-zero for bitcoin too. > > If N was 5%, then only 5% of bitcoin transactions _could_ be > > fraudulantly "charged back"; so then why wouldn't only 2% of those > > bitcoin transactions be fraudulant too, just as in the CC case? > > If you attempt fraud against a bank, they know who you are and will come > after you in one way or another. But it's safe to assume that users of a > double spend service would be anonymous and the kind of merchants they go > after are not hassling their customers with strong ID checks, so there > would be no consequences for them. It's a game they can only win. You're still being unfair to bitcoin. Not everyone who uses bitcoins will be dishonest. The dishonest 5% hashing power is not going to be used in 100% of any given merchants transactions. That's all I'm saying. You're original statement that we could end up in a position that bitcoin has a higher failure rate than credit cards seems unfair to me. > if N was only, say, 5%, and there was a large enough population of users who were systematically trying to defraud merchants, we'd already be having worse security than magstripe credit cards. "[If] there was a large enough population" -- why are bitcoin users more dishonest than credit card users? Most people are honest, so it seems unlikely that that 5% attack surface would be used at 100%; or even 40% necessary to equal the 2% chargeback rate with CC. I really didn't want to get into an argument over this: all I'm saying is that things aren't as bad as you painted them. Andy -- Dr Andy Parkins andyparkins@gmail.com