Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 71B1DA86 for ; Thu, 30 Jun 2016 16:52:35 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from outmail148102.authsmtp.net (outmail148102.authsmtp.net [62.13.148.102]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 6FA5F179 for ; Thu, 30 Jun 2016 16:52:34 +0000 (UTC) Received: from mail-c232.authsmtp.com (mail-c232.authsmtp.com [62.13.128.232]) by punt20.authsmtp.com (8.14.2/8.14.2/) with ESMTP id u5UGqWIR001719; Thu, 30 Jun 2016 17:52:32 +0100 (BST) Received: from petertodd.org (ec2-52-5-185-120.compute-1.amazonaws.com [52.5.185.120]) (authenticated bits=0) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id u5UGqTvo018382 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 30 Jun 2016 17:52:30 +0100 (BST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by petertodd.org (Postfix) with ESMTPSA id 799814010C; Thu, 30 Jun 2016 16:50:17 +0000 (UTC) Received: by localhost (Postfix, from userid 1000) id A8C3C2056F; Thu, 30 Jun 2016 12:52:27 -0400 (EDT) Date: Thu, 30 Jun 2016 12:52:27 -0400 From: Peter Todd To: Eric Voskuil , Bitcoin Protocol Discussion Message-ID: <20160630165227.GA5816@fedora-21-dvm> 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> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="6c2NcOVqGQ03X4Wi" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-Server-Quench: 08ff7fef-3ee3-11e6-829e-00151795d556 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdQIUEkAaAgsB AmAbWlNeVV97WmI7 bghPaBtcak9QXgdq T0pMXVMcUQANdl1l QEEeUxFxfwcIeX1z YUIsXngNCkMsIBBg QRsBFnAHZDJmdWgd WRVFdwNVdQJNdxoR b1V5GhFYa3VsNCMk FAgyOXU9MCtqYA50 eklUcAt6 X-Authentic-SMTP: 61633532353630.1037:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 52.5.185.120/25 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,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 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 16:52:35 -0000 --6c2NcOVqGQ03X4Wi Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jun 30, 2016 at 05:22:08PM +0200, Eric Voskuil via bitcoin-dev wrot= e: >=20 > > On Jun 30, 2016, at 2:43 PM, Jonas Schnelli wrot= e: > >=20 > >>>> The core problem posed by BIP151 is a MITM attack. The implied solut= ion (BIP151 + authentication) requires that a peer trusts that another is n= ot 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 m= ay > >>> know that he is intercepting the channel? > >>=20 > >> It is not clear to me why you believe an attack on privacy by an anony= mous 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 = these two nodes. How then do they maintain the chain? >=20 > The "middle" in this sense does not have to be the wire directly between = these two peers. It can be between either of them and any anonymous connect= ion 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 protectio= n will remain weak until the entire network is "secure". At that point it w= ould necessarily be a private network. >=20 > As Pieter rightly observes, there are and always will be tunnels between = trusting nodes. Often these are groups of nodes that are in collaboration, = so logically they are one node from a system security standpoint. But if pe= ople become generally reliant on good node registration, it will become the= registrar who controls access to the network. So my concern rests I this p= roposal becoming widely adopted. To be clear, are you against Bitcoin Core's tor support? Because node-to-node connections over tor are encrypted, and make use of on= ion addresses, which are self-authenticated in the exact same way as BIP151 proposes. And we're shipping that in production as of 0.12.0, and by default Tor onion support is enabled and will be automatically setup if you have a recent version of Tor installed. Does that "create pressure to expand node identity"? --=20 https://petertodd.org 'peter'[:-1]@petertodd.org --6c2NcOVqGQ03X4Wi Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQEcBAEBCAAGBQJXdU5IAAoJEGOZARBE6K+yGuoH/1gVZU+v0Kq/koTf8Axvs8qV 1hoYa9lg/oBSgS72ZxovtviOmKOWGrO8f9bDueBgLCAyTspKNXR8YynVpMnPAoLh tBsXFg9CE7IQkAfFpR0uE6xFck49M+zHOOcnXE1hGD5vLdI+zUsclexs2jxvPvJz SCeZsdQNh0E6dUeG1PjPesy0D9/g8UUqfhuXWox/MqtPmZEk/Td6a28RacCi7EW8 qo5IM/weH16GBKiY4FQA1YpmX8LhMDKpVOcg92TUhkVlkUemnlLTiUyTwCEWuVtz E42/DJ/teiUg6SgXoHVk9drv9Yufp31ithnf7b/Env6qT7p6VCnua7Zt0KmjgKw= =yv4n -----END PGP SIGNATURE----- --6c2NcOVqGQ03X4Wi--