From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CA3A52A37 for ; Mon, 18 Mar 2019 10:55:36 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from EUR03-AM5-obe.outbound.protection.outlook.com (mail-oln040092070041.outbound.protection.outlook.com [40.92.70.41]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 057FF148 for ; Mon, 18 Mar 2019 10:55:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=hotmail.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=XlxG1cTNeGoxX8dTU3uE4xflwzs6LyxRMx3p+kvVknw=; b=DIS/dGas6e9kRRH3fKuNdo0La1LQ1oU8iyukhGMv4/+XmBq3yaKNQFXOkXqS1+rH+Hb2tb2VSLb2iftlYO5ed1Hc1iaLiJR9/O7qPHo401lAhCtD42s3qBe/OyZd8sZkQoWqcaqWEjvazF/HFEI/zs+CpOLE4mWi8ubk/Df3Pjd88JfONo2id6+NdhVTKnTjRd21nXG3bhaP3lrYVe+uLIB5EDNiRX9uh7OewkZHppJUdkF+WtXni4iYOk14FxXNTWPKtc1kSt66+Du8BrePp2Ad/QGwgcfkJCnS4qJ8j3eaMqQss+hkDXVlO4zGyBY6dJT7ldzJ7ZxCura/9DBcmA== Received: from DB5EUR03FT055.eop-EUR03.prod.protection.outlook.com (10.152.20.56) by DB5EUR03HT192.eop-EUR03.prod.protection.outlook.com (10.152.21.210) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.20.1730.9; Mon, 18 Mar 2019 10:55:34 +0000 Received: from DB6PR10MB1832.EURPRD10.PROD.OUTLOOK.COM (10.152.20.55) by DB5EUR03FT055.mail.protection.outlook.com (10.152.21.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.20.1730.9 via Frontend Transport; Mon, 18 Mar 2019 10:55:34 +0000 Received: from DB6PR10MB1832.EURPRD10.PROD.OUTLOOK.COM ([fe80::71be:5864:9139:4f9c]) by DB6PR10MB1832.EURPRD10.PROD.OUTLOOK.COM ([fe80::71be:5864:9139:4f9c%3]) with mapi id 15.20.1709.015; Mon, 18 Mar 2019 10:55:34 +0000 From: "Kenshiro []" To: "bitcoin-dev@lists.linuxfoundation.org" Thread-Topic: Payjoin privacy with the receiver of the transaction Thread-Index: AQHU3Xi3TuLQzioN20KrtFTwOE2knQ== Date: Mon, 18 Mar 2019 10:55:34 +0000 Message-ID: Accept-Language: en-US, es-ES Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-incomingtopheadermarker: OriginalChecksum:778FA1B4BA25E245E1D36144A76AC10D4109BB1C5100AE845B849C5160DB179C; UpperCasedChecksum:83CF75915E808943C86B3EE97D142BE8E80C3A9B54CECEE2FF611F9D322C7DBB; SizeAsReceived:6673; Count:41 x-tmn: [yWuAxz1Hc4573H2KWqlFapyzsv2+1a2E] x-ms-publictraffictype: Email x-incomingheadercount: 41 x-eopattributedmessage: 0 x-microsoft-antispam: BCL:0; PCL:0; RULEID:(2390118)(7020095)(20181119110)(201702061078)(5061506573)(5061507331)(1603103135)(2017031320274)(2017031322404)(2017031324274)(2017031323274)(1601125500)(1603101475)(1701031045); SRVR:DB5EUR03HT192; x-ms-traffictypediagnostic: DB5EUR03HT192: x-microsoft-antispam-message-info: ZVlAgEr6ZAhSsIcMMV0iVLh6cYBZSoyFymxJx6ANSCgmv8CGPFfDlVd27R5bXhko Content-Type: multipart/alternative; boundary="_000_DB6PR10MB1832253A8D022C4A91573D49A6470DB6PR10MB1832EURP_" MIME-Version: 1.0 X-OriginatorOrg: hotmail.com X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-CrossTenant-Network-Message-Id: d492f41a-82f3-4ba0-533e-08d6ab903f1a X-MS-Exchange-CrossTenant-rms-persistedconsumerorg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-CrossTenant-originalarrivaltime: 18 Mar 2019 10:55:34.0483 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Internet X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB5EUR03HT192 X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HTML_MESSAGE, 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 X-Mailman-Approved-At: Mon, 18 Mar 2019 17:04:38 +0000 Subject: [bitcoin-dev] Payjoin privacy with the receiver of the transaction 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: Mon, 18 Mar 2019 10:55:36 -0000 --_000_DB6PR10MB1832253A8D022C4A91573D49A6470DB6PR10MB1832EURP_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi, I think Payjoin can be a very good privacy solution for Bitcoin, but I have= a question about it: - If a user has 1 BTC in a single address and make a payjoin payment to oth= er person of 0.1 BTC using that address as input, the other person can see = in a blockchain explorer the change address with an amount of 0.9 BTC. That= 's a serious privacy leak. I would like to know what will be the standard s= olution to this issue. An easy fix could be that the user wallet check if a= ny address contains a BTC amount higher than a "safe" amount like 0.01 BTC = or less. If some address exceed that amount the wallet could automatically = make 1 payment to itself to split the amount in several addresses. In this = way nobody receiving a payment from a user will ever know that he has a bit= coin balance higher than the "safe" amount. What do you think? Regards, --_000_DB6PR10MB1832253A8D022C4A91573D49A6470DB6PR10MB1832EURP_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi,

I think Payjoin can be a very good privacy solution for Bitcoin, but I= have a question about it:

- If a user has 1 BTC in a single address and make a payjoin payment t= o other person of 0.1 BTC using that address as input, the other person can= see in a blockchain explorer the change address with an amount of 0.9 BTC.= That's a serious privacy leak. I would like to know what will be the standard solution to this issue. An = easy fix could be that the user wallet check if any address contains a BTC = amount higher than a "safe" amount like 0.01 BTC or less. If some= address exceed that amount the wallet could automatically make 1 payment to itself to split the amount in several addr= esses. In this way nobody receiving a payment from a user will ever know th= at he has a bitcoin balance higher than the "safe" amount.

What do you think?

Regards,
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