Return-Path: Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 30511C002D for ; Mon, 1 Aug 2022 11:38:40 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id EC0F140439 for ; Mon, 1 Aug 2022 11:38:39 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org EC0F140439 Authentication-Results: smtp2.osuosl.org; dkim=pass (2048-bit key) header.d=protonmail.com header.i=@protonmail.com header.a=rsa-sha256 header.s=protonmail3 header.b=cUNyhnDx X-Virus-Scanned: amavisd-new at osuosl.org X-Spam-Flag: NO X-Spam-Score: -2.102 X-Spam-Level: X-Spam-Status: No, score=-2.102 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id zy3ImkkQWhqU for ; Mon, 1 Aug 2022 11:38:39 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 336C94028D Received: from mail-4324.protonmail.ch (mail-4324.protonmail.ch [185.70.43.24]) by smtp2.osuosl.org (Postfix) with ESMTPS id 336C94028D for ; Mon, 1 Aug 2022 11:38:39 +0000 (UTC) Date: Mon, 01 Aug 2022 11:38:29 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1659353916; x=1659613116; bh=ypzFTm56KXVMjd+Ru1y/yHIxrLSajfjWDtFxcknfTfY=; h=Date:To:From:Cc:Reply-To:Subject:Message-ID:In-Reply-To: References:Feedback-ID:From:To:Cc:Date:Subject:Reply-To: Feedback-ID:Message-ID; b=cUNyhnDxCNwVpnbCCemjZTcgyVHqQuWpU29MgsSHAWCUhaGAz8BBDDsWCF9INXRru bA3zJinkiJLtOPsgt5hMSKARx3sLfzMw0DP7Snz7xL1/jySg9/qPqqda3Bjx1e9ccm s/9QG5h4LgudEV9Sypv1UDrZXByBZJ26u5OkhZ2W7OxM7Pta32b7zNVo6dspWWXf7i QJFGWsTgIlQe3zg4GSjI/jWznR+G0DepI1g8XtVnMraHwr7ztToZgrVdZB2ioJ18vR /93E5MLj6eMjp6JNxh+e4KwNJG0YGVJzVnOoNR+RqRWmq23qYXeqYf4hhpvbdumZsq rE6FKtJlnM2xA== To: Ruben Somsen From: Alfred Hodler Reply-To: Alfred Hodler Message-ID: In-Reply-To: References: <-BUM-o-GxD7jpYy6cOdoALb-p2xbdEFds3De08nUFseeif6-OS6p_A7u7B_h45rkuflSix9kaC4e9fbOs_YwOL6xbrCF5ebjyGKurT4MeJU=@protonmail.com> Feedback-ID: 44065311:user:proton MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Mailman-Approved-At: Mon, 01 Aug 2022 12:10:46 +0000 Cc: Bitcoin Protocol Discussion Subject: Re: [bitcoin-dev] New BIP: Private Payments X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 01 Aug 2022 11:38:40 -0000 Hi Ruben, I have incorporated your feedback. Using only the first four bytes of the n= otification code is a very valuable suggestion, so thank you for that. I ha= ve added you as a co-author. In regards to hiding the recipient in the notification, the purpose is not = only to allow Alice to send a notification herself, but also to break the l= ink between the notifier (be that Alice or a third-party service) and Bob. = Not doing so would reintroduce the same problem we have with BIP47 and uniq= ue per-recipient notification addresses -- namely that of social graph buil= ding. The tradeoff, as you noticed, is that light clients have to rely on s= ome kind of OP_RETURN indexing service. I personally consider any inconveni= ence (to developers, as end users never see this) stemming from that to be = acceptable because: 1) it reduces the amount of social metadata on the blockchain 2) notification services might otherwise be pressured into censoring certai= n recipients 3) it allows wallets to decide the level of outsourcing they are comfortabl= e with 4) adversaries monitoring notifications might see a lot of notifications to= someone and use that information to mount an attack Thanks for all the feedback. Alfred