From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1YOsCH-0006rN-M4 for bitcoin-development@lists.sourceforge.net; Fri, 20 Feb 2015 18:21:05 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.213.177 as permitted sender) client-ip=209.85.213.177; envelope-from=gmaxwell@gmail.com; helo=mail-ig0-f177.google.com; Received: from mail-ig0-f177.google.com ([209.85.213.177]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1YOsCG-0004gx-UU for bitcoin-development@lists.sourceforge.net; Fri, 20 Feb 2015 18:21:05 +0000 Received: by mail-ig0-f177.google.com with SMTP id z20so5075353igj.4 for ; Fri, 20 Feb 2015 10:20:59 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.107.27.143 with SMTP id b137mr15153845iob.76.1424456459550; Fri, 20 Feb 2015 10:20:59 -0800 (PST) Received: by 10.107.16.80 with HTTP; Fri, 20 Feb 2015 10:20:59 -0800 (PST) In-Reply-To: References: Date: Fri, 20 Feb 2015 18:20:59 +0000 Message-ID: From: Gregory Maxwell To: Adam Back 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: 1YOsCG-0004gx-UU Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] bloom filtering, privacy 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, 20 Feb 2015 18:21:05 -0000 On Fri, Feb 20, 2015 at 5:59 PM, Adam Back wrote: > So now they ask a full node for merkle paths + transactions for the > addresses from the UTXO set from the block(s) that it was found in. Use of the words "UTXO set" here is probably confusing people as it's likely to make people think of the complete verification state. In this case it's simply referring to block-local data. (and thus avoids the large IO overheads of an actual UTXO set). It's a straight forward idea: there is a scriptpubkey bitmap per block which is committed. Users can request the map, and be SPV confident that they received a faithful one. If there are hits, they can request the block and be confident there was no censoring. It's possible to tree structure additional layers to the bitmap, so one can incrementally query to trade0off map size for false request overhead, it's not clear to me how much of a win this would be for normal parameters.. It's also possible to extract the txout list for the whole block and commit to that too so it's possible to request just the outputs and get a faithful copy of them, which is _much_ smaller than the block overall.