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From: Eric Voskuil <eric@voskuil.org>
In-Reply-To: <CAAS2fgRGbnH-NtPRdLe0yhFSoqJ7b6O25LfyGv_ULHhy8bBSpg@mail.gmail.com>
Date: Tue, 28 Jun 2016 23:59:54 +0200
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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>
	<20160628203605.GA1328@fedora-21-dvm>
	<E8335291-7142-4E21-A1E2-76F387426741@voskuil.org>
	<CAAS2fgRGbnH-NtPRdLe0yhFSoqJ7b6O25LfyGv_ULHhy8bBSpg@mail.gmail.com>
To: Gregory Maxwell <greg@xiph.org>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] BIP 151
Precedence: list


> On Jun 28, 2016, at 11:36 PM, Gregory Maxwell <greg@xiph.org> wrote:
>=20
> On Tue, Jun 28, 2016 at 9:22 PM, Eric Voskuil via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> An "out of band key check" is not part of BIP151.
>=20
> It has a session ID for this purpose.

Passing the session ID out of band is authentication. As this is explicitly n=
ot part of BIP151 it cannot be that BIP151 provides the tools to detect a at=
tack (the point at issue).

>> It requires a secure channel and is authentication. So BIP151 doesn't pro=
vide the tools to detect an attack, that requires authentication. A general r=
equirement for authentication is the issue I have raised.
>=20
> One might wonder how you ever use a Bitcoin address, or even why we might g=
uess these emails from "you" aren't actually coming from the NSA.

The sarcasm is counterproductive Greg. By the same token I could ask how you=
 ever use Bitcoin given that the P2P protocol is not encrypted or authentica=
ted.

It doesn't matter who I am, maybe I am the NSA. I don't argue from a positio=
n of authority. Signing my emails while traveling on holiday with only my ph=
one gets a little tedious.

The blockchain and mempool are a cache of public data. Transmission of a pay=
ment address to a payer is not a comparable scenario.

The possibility that authentication may become required to participate in th=
is trustless network is a legitimate concern, and one that has not been addr=
essed.

e=