Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Y9Za0-0002UM-RW for bitcoin-development@lists.sourceforge.net; Fri, 09 Jan 2015 13:26:20 +0000 Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.223.170 as permitted sender) client-ip=209.85.223.170; envelope-from=gmaxwell@gmail.com; helo=mail-ie0-f170.google.com; Received: from mail-ie0-f170.google.com ([209.85.223.170]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1Y9ZZz-00028u-Vt for bitcoin-development@lists.sourceforge.net; Fri, 09 Jan 2015 13:26:20 +0000 Received: by mail-ie0-f170.google.com with SMTP id rd18so14898132iec.1 for ; Fri, 09 Jan 2015 05:26:14 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.107.168.18 with SMTP id r18mr14810649ioe.76.1420809974701; Fri, 09 Jan 2015 05:26:14 -0800 (PST) Received: by 10.107.16.30 with HTTP; Fri, 9 Jan 2015 05:26:14 -0800 (PST) In-Reply-To: References: Date: Fri, 9 Jan 2015 13:26:14 +0000 Message-ID: From: Gregory Maxwell To: Mike Hearn Content-Type: text/plain; charset=UTF-8 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 (gmaxwell[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: 1Y9ZZz-00028u-Vt Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Bi-directional micropayment channels with CHECKLOCKTIMEVERIFY 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: Fri, 09 Jan 2015 13:26:21 -0000 On Fri, Jan 9, 2015 at 1:20 PM, Mike Hearn wrote: >> A limitation on most existing micropayment channel ideas is that payments >> can only flow in one direction. > It's worth noting that the original protocol as designed by Satoshi did not > have this limitation. It has evolved this way because of ad-hoc DoS fixes > over time (btw I'm not saying they were the wrong thing to do, as non "ad > hoc" solutions are significantly more work). But it seems like eventually a > different approach to handling DoS attacks based on resource prioritisation > and scheduling will become needed / implemented, and at that point the > original design could be safely brought back to life. I don't agree with your understanding. Expecting replacement to work and be enforced is completely unsafe. People (sanely) refuse to use protocols which are broken by refund malleability, which is a much narrower expectation for miners than expecting the sequence ratchet to go one way.