From: Jonas Schnelli <dev@jonasschnelli.ch>
Message-Id: <FBFEE1B5-9243-45DA-A8F6-1449591DCAB6@jonasschnelli.ch>
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Date: Wed, 8 Mar 2017 22:31:01 +0100
In-Reply-To: <18390846.ckRIaq9dAb@strawberry>
To: Tom Zander <tomz@freedommail.ch>
References: <BL2PR03MB435C5077E69D91D0A8092B6EE2A0@BL2PR03MB435.namprd03.prod.outlook.com>
	<D4B674DB-8F2E-4AA1-B271-FEE02A62A274@voskuil.org>
	<30362205-D0CC-46D9-B924-EFA0A6EA1AC9@jonasschnelli.ch>
	<18390846.ckRIaq9dAb@strawberry>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Unique node identifiers (and BIP150)
Precedence: list


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Hi Tom

> Do you know the trick of having an open wifi basestation in a public =
street
> and how that can lead to tracking? Especially if you have a network of =
them.
> The trick is this; you set up an open wifi base station with a hidden =
ssid
> and phones try to connect to it by saying =E2=80=9CAre you =
ssid=3Dxyz?=E2=80=9D
> This leads the basestation to know that the phone has known =
credentials with
> another wifi that has a specific ssid. (the trick is slightly more =
elaborate,
> but the basics are relevant here).
>=20
> Your BIP is vulnarable to the same issue, as a node wants to connect =
using
> the AUTHCHALLENGE which has as an argument the hash of the person =
I=E2=80=99m trying
> to connect with.

This thread is not about BIP150/151.
The hash includes the encryption session which makes it impossible to =
distinct identities.

>=20
> Your BIP says "Fingerprinting the requesting peer is not possible=E2=80=9D=
.
> Unfortunately, this is wrong. Yes the peer is trivial to fingerprint. =
Your
> hash never changes and as you connect to a node anyone listening can =
see you
> sending the same hash on every connect to that peer, whereever you are =
or
> connect from.

Not true. The hash includes the encryption session which is based on a =
ephemeral ECDH/HKDF per connection-session.

Have you read the BIP?

</jonas>


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