Date: Tue, 28 Jun 2016 16:36:05 -0400
From: Peter Todd <pete@petertodd.org>
To: Eric Voskuil <eric@voskuil.org>
Message-ID: <20160628203605.GA1328@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>
	<20160628182202.GA5519@fedora-21-dvm>
	<D40F9E9D-DB6C-4083-A9E8-C5EBC363DB30@voskuil.org>
	<20160628201447.GA1148@fedora-21-dvm>
	<4DCF7DD2-6533-4F79-8CA1-871B67C01BDA@voskuil.org>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha256;
	protocol="application/pgp-signature"; boundary="sm4nu43k4a2Rpi4c"
Content-Disposition: inline
In-Reply-To: <4DCF7DD2-6533-4F79-8CA1-871B67C01BDA@voskuil.org>
User-Agent: Mutt/1.5.23 (2014-03-12)
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] BIP 151
Precedence: list


--sm4nu43k4a2Rpi4c
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Tue, Jun 28, 2016 at 10:29:54PM +0200, Eric Voskuil wrote:
>=20
>=20
> > On Jun 28, 2016, at 10:14 PM, Peter Todd <pete@petertodd.org> wrote:
> >=20
> >> On Tue, Jun 28, 2016 at 08:35:26PM +0200, Eric Voskuil wrote:
> >> Hi Peter,
> >>=20
> >> What in this BIP makes a MITM attack easier (or easy) to detect, or in=
creases the probability of one being detected?
> >=20
> > BIP151 gives users the tools to detect a MITM attack.
> >=20
> > It's kinda like PGP in that way: lots of PGP users don't properly check=
 keys,
>=20
> PGP requires a secure side channel for transmission of public keys. How d=
oes one "check" a key of an anonymous peer? I know you well enough to know =
you wouldn't trust a PGP key received over an insecure channel.
>=20
> All you can prove is that you are talking to a peer and that communicatio=
ns in the session remain with that peer. The peer can be the attacker. As J=
onas has acknowledged, authentication is required to actually guard against=
 MITM attacks.

Easy: anonymous peers aren't always actually anonymous.

A MITM attacker can't easily distinguish communications between two nodes t=
hat
randomly picked their peers, and nodes that are connected because their
operators manually used -addnode to peer; in the latter case the operators =
can
check whether or not they're being attacked with an out-of-band key check.

--=20
https://petertodd.org 'peter'[:-1]@petertodd.org

--sm4nu43k4a2Rpi4c
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: Digital signature

-----BEGIN PGP SIGNATURE-----

iQEcBAEBCAAGBQJXct+yAAoJEGOZARBE6K+y3xsH/Rj54dTZN0nFB2vU4CzonS00
Iljo9i0FXlo12qHcMgDRBnXu27Lh6wVuAlADf+gIPiGUKC8PUvGDxtqvIPTz7R+r
lAoHvycHZ+PxVX4QdV8FCjzRlHRRV/2cHuhqemBBqGNx/rJskp59Ed2bnEur0wh3
CrU3Kd32h5aXBZA0FHcYSvL7GSig6GNqk3in8q6iYpC5Zs5djqm5kg5/3wWINNyF
9UVhJyjSbYTHk9ow3MRg4AKaxlB1Ksf2nWRrq+1J7U7v9ACjMjEttU30PmPugiFE
rhYuS/q6wXgjvajrvCuiRirxVAUiFwRvsqrGWqNXZzYij1f4JgyR3JTFX/bo1QM=
=t4hw
-----END PGP SIGNATURE-----

--sm4nu43k4a2Rpi4c--