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 1Wsq3j-0005wj-9M for bitcoin-development@lists.sourceforge.net; Fri, 06 Jun 2014 09:03:35 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of petertodd.org designates 62.13.149.101 as permitted sender) client-ip=62.13.149.101; envelope-from=pete@petertodd.org; helo=outmail149101.authsmtp.com; Received: from outmail149101.authsmtp.com ([62.13.149.101]) by sog-mx-3.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1Wsq3h-0006UQ-FY for bitcoin-development@lists.sourceforge.net; Fri, 06 Jun 2014 09:03:35 +0000 Received: from mail-c235.authsmtp.com (mail-c235.authsmtp.com [62.13.128.235]) by punt15.authsmtp.com (8.14.2/8.14.2/) with ESMTP id s5693NHQ067956; Fri, 6 Jun 2014 10:03:23 +0100 (BST) Received: from savin (76-10-178-109.dsl.teksavvy.com [76.10.178.109]) (authenticated bits=128) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id s5693GWq001591 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Fri, 6 Jun 2014 10:03:19 +0100 (BST) Date: Fri, 6 Jun 2014 05:04:41 -0400 From: Peter Todd To: Adam Back Message-ID: <20140606090441.GA19256@savin> References: <20140606081933.GA29458@savin> <20140606084852.GA30247@netbook.cypherspace.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="+HP7ph2BbKc20aGI" Content-Disposition: inline In-Reply-To: <20140606084852.GA30247@netbook.cypherspace.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-Server-Quench: 67cfe70d-ed59-11e3-b396-002590a15da7 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdgQUEkAaAgsB AmIbWlReUF57W2M7 bAxPbAVDY01GQQRq WVdMSlVNFUsrBBoI BWl5ExlydgBPeTBx ZkdrWD5dWxcsIEF9 FlMBQWgPeGZhPWMC AkNRcR5UcAFPdx8U a1UrBXRDAzANdhES HhM4ODE3eDlSNilR RRkIIFQOdA4tORIR cDomOhIKVVYIXTsy JBFuIF8AdAAA X-Authentic-SMTP: 61633532353630.1023:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 76.10.178.109/587 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: 1Wsq3h-0006UQ-FY Cc: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] NODE_BLOOM service bit 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 Jun 2014 09:03:35 -0000 --+HP7ph2BbKc20aGI Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jun 06, 2014 at 10:48:52AM +0200, Adam Back wrote: > Advertising NODE BLOOM as a service sounds good. >=20 > But the critique of bloom filters, I am not so sure prefix filters are > better. Prefix filters offer questionable privacy tradeoffs in my > opinion. Same problem as with stealth address proposed use of > prefixes. That's assuming you're doing the proposed prefix brute forcing - if you don't do that they have privacy equal or better than bloom filters, but with better scalability. In particular that better scalability lets you efficiently query multiple servers for blockchain data, only giving up info on a subset of the addresses in your wallet to each server. This can be a significant improvement to bloom filters if your attacker is running logging nodes to try to, say, deanonymize CoinJoin transactions. > All for scalability, efficiency and decentralization but not ideally at t= he > expense of nuking privacy. The effects on privacy are cumulative, and > affect everyone not just the user. Same pattern of local decision, global > effect as with reused addresses. Indeed. But again, remember that the existing systems suck too; prefix-brute forcing is a engineering tradeoff implementable with existing and well understood technology. Now if you want to come up with something better and write code, please do! I'm sure the math exists; what doesn't exist is robust and well tested code in multiple languages. Stealth addresses at least have been designed so that future blockchain filter upgrades can be added in a backwards compatible way. --=20 'peter'[:-1]@petertodd.org 00000000000000003a68ee16d702ca5dd5547fb4aead910a004747cb06241dd6 --+HP7ph2BbKc20aGI Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (GNU/Linux) iQGrBAEBCACVBQJTkYQlXhSAAAAAABUAQGJsb2NraGFzaEBiaXRjb2luLm9yZzAw MDAwMDAwMDAwMDAwMDAzYTY4ZWUxNmQ3MDJjYTVkZDU1NDdmYjRhZWFkOTEwYTAw NDc0N2NiMDYyNDFkZDYvFIAAAAAAFQARcGthLWFkZHJlc3NAZ251cGcub3JncGV0 ZUBwZXRlcnRvZC5vcmcACgkQJIFAPaXwkfsYsgf/fOfAbgWX9Ti6rp4DzXYDPg5p Up6gr7vP061am91secxm9nRd5wV13Lp4TIRhrJh7nXm/Gi3O63E210hKWxSxe1pq d39cDq18sInRI2jmPjwt66uTw5qJrjjTSpOnITKhn+u7ingrBbO1EjodS7xZEWA8 u7lDcgcn6O9GoGflcF55B8dhbHu+UbBW4oD0V1qDNZtLFV0ROZgfDft7J6bu3ZhT 9af1J15td2qeHf3hkV64rE6U5FeNQX9qDArkhDmDKGUYyVmBmnC8sq9x3KhTMA9n KsKutmYDL6geY3o+xfOxKby9qta7zFNV0bDzzuY7n1M7ApTtkKXjKDwaGSO4Xg== =i3Mu -----END PGP SIGNATURE----- --+HP7ph2BbKc20aGI--