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-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1XJQat-0001df-LF for bitcoin-development@lists.sourceforge.net; Mon, 18 Aug 2014 17:19:43 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of bitpay.com designates 209.85.213.49 as permitted sender) client-ip=209.85.213.49; envelope-from=jgarzik@bitpay.com; helo=mail-yh0-f49.google.com; Received: from mail-yh0-f49.google.com ([209.85.213.49]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1XJQas-0007DR-HV for bitcoin-development@lists.sourceforge.net; Mon, 18 Aug 2014 17:19:43 +0000 Received: by mail-yh0-f49.google.com with SMTP id b6so4739273yha.36 for ; Mon, 18 Aug 2014 10:19:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-type; bh=FXDv2MB+Iek8Vj7wA7OlKXVdyY+6PuPRjW/pMUJ1Lso=; b=lzit7LDGOQOTdNfdFybgv1EicQY7zBMDkIbmYDrC+XxFVGIjv/ws2zdseHORc3n0DW JOs1gEtouSygQcz/WylKktU6GnNnR1YAX94+MAbiB+9RMZMnUUAeQB014zwa0G+gCGP7 GN4n2SzQJ99YsINs5pnaZeOV8jW4K7Z43n+dSnba6XoRj8WB+NFKcjTHEZeocYTlZaOi b7TI9C8DERMjXs2uwr3y9IzMUfEt1tgB1NFb5M8CbSFupz0tqKpZvBDFkXq/44cOTae4 cj8Ekq3c+M8m0evpa6Edj8+O3SAkv1E7Xlf2lxvSafKmaJKdDGGgYVy5B2iJLaw+BrK9 a1YQ== X-Gm-Message-State: ALoCoQlzK05ag+XFOsU6BeN01LN8h6Rld472It+qRkPOxNbrer6K1olz+2atfIONHrDZ7FCB4EPR X-Received: by 10.236.15.6 with SMTP id e6mr55676097yhe.43.1408382375932; Mon, 18 Aug 2014 10:19:35 -0700 (PDT) MIME-Version: 1.0 Received: by 10.170.37.200 with HTTP; Mon, 18 Aug 2014 10:19:15 -0700 (PDT) In-Reply-To: <20140818164543.GB31175@localhost.localdomain> References: <20140818164543.GB31175@localhost.localdomain> From: Jeff Garzik Date: Mon, 18 Aug 2014 13:19:15 -0400 Message-ID: To: Ivan Pustogarov Content-Type: text/plain; charset=UTF-8 X-Spam-Score: -1.6 (-) 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 -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1XJQas-0007DR-HV Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Outbound connections rotation 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: Mon, 18 Aug 2014 17:19:43 -0000 Simply by observing timing from sufficiently geo-graphically and network-ly dispersed nodes, you may deduce the original broadcaster of a transaction. Rotating peers doesn't help. That said, periodic rotation can be helpful. Every 2-10 minutes is excessive. On Mon, Aug 18, 2014 at 12:46 PM, Ivan Pustogarov wrote: > Hi there, > > I'd like to start a discussion on periodic rotation of outbound connections. > E.g. every 2-10 minutes an outbound connections is dropped and replaced > by a new one. > > Motivation: > Each bitcoin non-UPnP client behind NAT has 8 outbound connections > which change only rarely (due to occasional remote side disconnections). > A subset of these 8 entry nodes uniquely identifies a user. > An attacker can listen for transactions in Bitcoin network and for each > transaction record the first 8 peers which forwarded the transaction. > If two distinct transactions (with unrelated bitcoin addresses) > come from the same set of 8 peers, the attacker can conclude that they > originated from the same user. This gives another method (in addition > to transaction graph analysis) for an attacker to link different BC > addresses of the same user. > Also note that by default bitcoin clients advertise their public IP > addresses. The attacker can link the advertised IP's to corresponding > 8 entry nodes and use it to deanonymise Bitcoin clients. > > If a bitcoin client periodically rotates his set of outbound > connections, his 8-peers fingerprint is blurred over time. > > Corresponding pull request is #4723. > > Some details are here: https://www.cryptolux.org/index.php/Bitcoin > > -- > Ivan > > ------------------------------------------------------------------------------ > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- Jeff Garzik Bitcoin core developer and open source evangelist BitPay, Inc. https://bitpay.com/