Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 093B092B for ; Tue, 16 May 2017 00:00:00 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-vk0-f49.google.com (mail-vk0-f49.google.com [209.85.213.49]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 5E129E9 for ; Mon, 15 May 2017 23:59:59 +0000 (UTC) Received: by mail-vk0-f49.google.com with SMTP id y190so57421506vkc.1 for ; Mon, 15 May 2017 16:59:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=kHw66TQ8xUaKbTbpBS6OR92vGgMpKYFKLMG/8C3CMAg=; b=QT85x3xQDJFaLKq7T/j8MOO0Yd1dZrjBRPjx/VTT19MBWQpGwgyBXCGsursyXlXLO4 J+SEUXQRdUyvEpT3c/Z7NMzb6WARhohgOEDKFWuF+79t0QER5dKWsTpGZ+Ib93k4/pMq Y7TzQ4kqdAiXq06iMvDM6v9tn1h+jAzfhOHeVx7D33JeVl6jSKSN4nMeDucEb7gFQU6n Fx7kzwaPZK8jBLeQfQaFM2Hmwr5iLBzbtJvcNgtyh/AYc69eplSTUskD3bsedAbJeVSs N1QJgLiAUJRBLPdpemU/L4mHIDSvyWLjabP5iJ5hlcefujmSWCtQH3Ql6FnxTCTyXu0Y m+4g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=kHw66TQ8xUaKbTbpBS6OR92vGgMpKYFKLMG/8C3CMAg=; b=Kk3BSA8eqpWvPB5AVDPwJoab3aR3tUFG5NkoYwSDAjsOsKhtRgKIyNhmZVxZZrhpMq BJHEvxHPNUIYWX6KSJehYfkVldOEvLGM31RPBHE/ecRSbozQlCgPIFFdOgUXXYQfdp8+ QAofuGHQtMfT+f7v7qgu8e/eUCVWeqozylZFgDZOk9p6nh9t7Lzse+Mn9ex9d83N+dUL ojm1xtrlIpz/lT504Tp6nvhiS1Nx144dKCXL6rlQYYP2fs4D/GMAAg7AqJPcJ/qxtD6Q 1U4/5lprxlLWeGM+5e2Zx0qslaHzg8loMzTYfmBExu2/IZ00nxFs3csoeuMy8BYNKvZe XdvQ== X-Gm-Message-State: AODbwcDVBXEsnRQ8ZCTKify451Ebsssq3oBZ6F9yQNklyOhCcsF85udz 7VFO4QmQrP9JU/5mMhQwWpk9JRwvtQ== X-Received: by 10.31.137.145 with SMTP id l139mr4269911vkd.39.1494892798543; Mon, 15 May 2017 16:59:58 -0700 (PDT) MIME-Version: 1.0 Sender: gmaxwell@gmail.com Received: by 10.103.20.66 with HTTP; Mon, 15 May 2017 16:59:58 -0700 (PDT) In-Reply-To: References: From: Gregory Maxwell Date: Mon, 15 May 2017 23:59:58 +0000 X-Google-Sender-Auth: rsiJSVyIlVPUlULgTuwLXj8MpVk Message-ID: To: ZmnSCPxj Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE 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] Rolling UTXO set hashes X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 May 2017 00:00:00 -0000 On Mon, May 15, 2017 at 11:04 PM, ZmnSCPxj via bitcoin-dev wrote: > transactions is in the header, which would let lite nodes download a UTXO > set from any full node and verify it by verifying only block headers > starting from genesis. Ya, lite nodes with UTXO sets are one of the the oldest observed advantages of a commitment to the UTXO data: https://bitcointalk.org/index.php?topic=21995.0 But it requires a commitment. And for most of the arguments for those you really want compact membership proofs. The recent rise in interest in full block lite clients (for privacy reasons), perhaps complements the membership proofless usage. Pieter describes some uses for doing something like this without a commitment. In my view, it's more interesting to first gain experience with an operation without committing to it (which is a consensus change and requires more care and consideration, which are easier if people have implementation experience). > rather than merkle tree root of transactions is in the header, For audibility and engineering reasons it would need to be be in addition to rather than rather than, because the proof of work needs to commit to the witness data (in that kind of flip, the transactions themselves become witnesses for UTXO deltas) or you get trivial DOS attacks where people provide malleated blocks that have invalid witnesses.