From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1YJXYM-0000BD-Ux for bitcoin-development@lists.sourceforge.net; Fri, 06 Feb 2015 01:17:50 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of petertodd.org designates 62.13.149.58 as permitted sender) client-ip=62.13.149.58; envelope-from=pete@petertodd.org; helo=outmail149058.authsmtp.co.uk; Received: from outmail149058.authsmtp.co.uk ([62.13.149.58]) by sog-mx-4.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1YJXYL-0002tE-Ob for bitcoin-development@lists.sourceforge.net; Fri, 06 Feb 2015 01:17:50 +0000 Received: from mail-c235.authsmtp.com (mail-c235.authsmtp.com [62.13.128.235]) by punt16.authsmtp.com (8.14.2/8.14.2/) with ESMTP id t161HhwA092592; Fri, 6 Feb 2015 01:17:43 GMT Received: from muck (99-121-56-190.lightspeed.sntcca.sbcglobal.net [99.121.56.190]) (authenticated bits=128) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id t161HSAa078684 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Fri, 6 Feb 2015 01:17:38 GMT Date: Thu, 5 Feb 2015 17:17:26 -0800 From: Peter Todd To: Isidor Zeuner Message-ID: <20150206011726.GJ32226@muck> References: <20150204142323.DEC4BE2DCDE@quidecco.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="lqaZmxkhekPBfBzr" Content-Disposition: inline In-Reply-To: <20150204142323.DEC4BE2DCDE@quidecco.de> X-Server-Quench: f33770af-ad9d-11e4-b396-002590a15da7 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aAdMdgQUHlAWAgsB AmMbW1VeUVp7XWE7 YgNPbAdcfE9IQQRj UFdMSlVNFUssABoA fn1vAxl1fwNOfDB3 bUBrECZYX0N9dRcr Xx8AHDkbZGY1bH1N U0leagNUcgZDfk5E bwQuUz1vNG8XDQg5 AwQ0PjZ0MThBJSBS WgQAK04nCUoGAjMm QhEEHDMgVUYFTiM8 IlQvJlIGEV0KP156 LEAgX11QLx8faEVa EkhWHGdCJlYHRiQq BgpcQQYSETJcXTw0 X-Authentic-SMTP: 61633532353630.1023:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 99.121.56.190/587 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Spam-Score: -1.5 (-) 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 SPF_PASS SPF: sender matches SPF record X-Headers-End: 1YJXYL-0002tE-Ob Cc: Bitcoin Development Subject: Re: [Bitcoin-development] determining change addresses using the least significant digits 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, 06 Feb 2015 01:17:51 -0000 --lqaZmxkhekPBfBzr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 04, 2015 at 03:23:23PM +0100, Isidor Zeuner wrote: > Hi there, >=20 > traditionally, the Bitcoin client strives to hide which output > addresses are change addresses going back to the payer. However, > especially with today's dynamically calculated miner fees, this > may often be ineffective: >=20 > A user sending a payment using the Bitcoin client will usually enter > the payment amount only up to the number of digits which are > considered to be significant enough. So, the least significant digits > will often be zero for the payment. With dynamically calculated miner > fees, this will often not be the case for the change amount, making it > easy for an observer to classify the output addresses. >=20 > A possible approach to handle this issue would be to add a randomized > offset amount to the payment amount. This offset amount can be small > in comparison to the payment amount. >=20 > Any thoughts? Have you looked at Armory? IIRC they do this kind of stuff. --=20 'peter'[:-1]@petertodd.org 0000000000000000165ecbd638ec09226f84c34d3d775d34ca5df4abfa8cb57c --lqaZmxkhekPBfBzr Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQGrBAEBCACVBQJU1BYiXhSAAAAAABUAQGJsb2NraGFzaEBiaXRjb2luLm9yZzAw MDAwMDAwMDAwMDAwMDAxNjVlY2JkNjM4ZWMwOTIyNmY4NGMzNGQzZDc3NWQzNGNh NWRmNGFiZmE4Y2I1N2MvFIAAAAAAFQARcGthLWFkZHJlc3NAZ251cGcub3JncGV0 ZUBwZXRlcnRvZC5vcmcACgkQJIFAPaXwkfs4xQf6A/0e97srNMB/R6jQNDOPchV8 mCK+yqIVou60QGyklxkXUN1EW/b60pyd8KwFnWcnvVkNacGseMu5xoel9ZmqAyel sV8nZf3e0dhZdbhG/nij36z3DqbbmHREYSNl6p42d4uJ/TFCuTfYkLUiz2a9AgE3 GwVlhedyIIhoQN+aEu2Vqdv9Z/pNMSrIKv1rTN1OtC2DRQ0JybguUCLxwEqE+YoW 8qBoaywjnWcJ4d4bpU8wbFRkbyB+XfXfd7jRpr0/2rP78N3TLFVRiKUAD0yqdOKT iBYaBlS1jXyzYPvyqTQmLCjMBCbhuXLembtF50yxoQH1lrKHiz4dZAp4RjGajQ== =GwFK -----END PGP SIGNATURE----- --lqaZmxkhekPBfBzr--