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 2921DA97 for ; Thu, 30 Jun 2016 18:25:50 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-wm0-f51.google.com (mail-wm0-f51.google.com [74.125.82.51]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 3226711D for ; Thu, 30 Jun 2016 18:25:49 +0000 (UTC) Received: by mail-wm0-f51.google.com with SMTP id r201so130706014wme.1 for ; Thu, 30 Jun 2016 11:25:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=voskuil-org.20150623.gappssmtp.com; s=20150623; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=9/QalzsQk548Z6ibdcOLSizLBUGXNo7fyhUzlyNenoo=; b=aICYIsBlr9x6sTNIsRe/rLJP81w+Azpaieo/1MpNglYP3mJah9XrMQkou+9AdYQ83h mYSJgorpU+8J+Xtk3ILnA53Wz1ZTJbrQgOI+oQfDPCAnVinejFMfolef6/52+sRUviP7 aIIWcfCSBWQbK7RvhM3eDc7oTi+VhwrQM2Zk+z5jmR3jg2B4ldAqUvxVUsc/iZFlga3t xykPPccPTDGbgaWAoJ+4htSlJlD7iNikYGnpARpadrKzlqs5Ufrk7dOjemdR5rhCRiW6 fIUNTEnPhEQS1kGdN8Da3yd6+L/bzG8nK7bbSl48ortzaaUtH8V1Lgpw++b39o+q4SXA sGwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=9/QalzsQk548Z6ibdcOLSizLBUGXNo7fyhUzlyNenoo=; b=FXYjkT9QH9URVfybyD42tUa0A4YViSdP3EMUTxxmw7KICje6O9p1E0Z2GnGFjcUjCr mXfdGZbEshZZnIDBMlTPjHCu16B868GIafmQ6rlNUXiuU9f4T6FYUifTF+wzlsWUGT2Q 8htjVhzqfFI6E87dtiyoS77Kanjc9VJII3BshfvPC6FyKchKa7rJe0KpJw9oADdYXu1b J2OkbdjhOv5J+niNQyjfcuw6M2riY8JT3wKrQop2pyuf5k5O2m2H3H4nJ/afnr6sGEFR lCSO9NzGc4Hqrf2LO3sn1MYGVHER3e5dGDHuYJQpi7HnETx6x/4KSWzpChqmDx3ycDDG 3ffQ== X-Gm-Message-State: ALyK8tISfwiyMQea4pJudQvNCXNPXbjDQdw/da1MYgl/2pE3e3IbQs/lnDksM2MAYnw83g== X-Received: by 10.194.88.5 with SMTP id bc5mr16474295wjb.100.1467311147594; Thu, 30 Jun 2016 11:25:47 -0700 (PDT) Received: from [197.161.189.105] ([197.161.189.105]) by smtp.gmail.com with ESMTPSA id jf3sm4733101wjb.41.2016.06.30.11.25.46 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 30 Jun 2016 11:25:46 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (1.0) From: Eric Voskuil X-Mailer: iPhone Mail (13F69) In-Reply-To: <20160630165227.GA5816@fedora-21-dvm> Date: Thu, 30 Jun 2016 20:25:45 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <663B51FE-D8D5-4570-ACA6-D1405D98C773@voskuil.org> References: <87h9cecad5.fsf@rustcorp.com.au> <1E86A00F-0609-4DBC-9543-94AE04CC13C9@voskuil.org> <577234A4.3030808@jonasschnelli.ch> <360EF9B8-A174-41CA-AFDD-2BC2C0B4DECB@voskuil.org> <20160629111728.GO13338@dosf1.alfie.wtf> <2981A919-4550-4807-8ED9-F8C51B2DC061@voskuil.org> <57750EAB.3020105@jonasschnelli.ch> <426C2AA3-BFB8-4C41-B4DF-4D6CC11988B2@voskuil.org> <577513DB.60101@jonasschnelli.ch> <20160630165227.GA5816@fedora-21-dvm> To: Peter Todd X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, MIME_QP_LONG_LINE, RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Protocol Discussion Subject: Re: [bitcoin-dev] BIP 151 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: Thu, 30 Jun 2016 18:25:50 -0000 > On Jun 30, 2016, at 6:52 PM, Peter Todd wrote: >=20 >> On Thu, Jun 30, 2016 at 05:22:08PM +0200, Eric Voskuil via bitcoin-dev wr= ote: >>=20 >>> On Jun 30, 2016, at 2:43 PM, Jonas Schnelli wrote= : >>>=20 >>>>>> The core problem posed by BIP151 is a MITM attack. The implied soluti= on (BIP151 + authentication) requires that a peer trusts that another is not= an attacker. >>>>>=20 >>>>> BIP151 would increase the risks for MITM attackers. >>>>> What are the benefits for Mallory of he can't be sure Alice and Bob ma= y >>>>> know that he is intercepting the channel? >>>>=20 >>>> It is not clear to me why you believe an attack on privacy by an anonym= ous peer is detectable. >>>=20 >>> If Mallory has substituted the ephemeral keys in both directions, at the= >>> point where Alice and Bob will do an authentication, they can be sure >>> Mallory is listening. >>=20 >> I understand the mechanics of a tunnel between trusting parties that have= a secure side channel. But this assumes that no other peer can connect to t= hese two nodes. How then do they maintain the chain? >>=20 >> The "middle" in this sense does not have to be the wire directly between t= hese two peers. It can be between either of them and any anonymous connectio= n they (must) allow. >>=20 >> Of course this creates pressure to expand their tunnel. Hence the problem= of expanding node identity in an effort to preserve privacy. The protection= will remain weak until the entire network is "secure". At that point it wou= ld necessarily be a private network. >>=20 >> As Pieter rightly observes, there are and always will be tunnels between t= rusting nodes. Often these are groups of nodes that are in collaboration, so= logically they are one node from a system security standpoint. But if peopl= e become generally reliant on good node registration, it will become the reg= istrar who controls access to the network. So my concern rests I this propos= al becoming widely adopted. >=20 > To be clear, are you against Bitcoin Core's tor support? >=20 > Because node-to-node connections over tor are encrypted, and make use of o= nion > addresses, which are self-authenticated in the exact same way as BIP151 pr= oposes. BIP151 is self-admittedly insufficient to protect against a MITM attack. It p= roposes node identity to close this hole (future BIP required). The yet-to-b= e-specified requirement for node identity is the basis of my primary concern= . This is not self-authentication. > And we're shipping that in production as of 0.12.0, and by default Tor oni= on support is enabled and will be automatically setup if you have a recent v= ersion of Tor installed. >=20 > Does that "create pressure to expand node identity"? The orthogonal question of whether Tor is safe for use with the Bitcoin P2P p= rotocol is a matter of existing research. e=