Return-Path: <luke@dashjr.org>
Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org
	[172.17.192.35])
	by mail.linuxfoundation.org (Postfix) with ESMTPS id E1B0369
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Thu, 24 Mar 2016 02:17:18 +0000 (UTC)
X-Greylist: from auto-whitelisted by SQLgrey-1.7.6
Received: from zinan.dashjr.org (zinan.dashjr.org [192.3.11.21])
	by smtp1.linuxfoundation.org (Postfix) with ESMTP id 39D3F10A
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Thu, 24 Mar 2016 02:17:18 +0000 (UTC)
Received: from ishibashi.localnet (unknown
	[IPv6:2001:470:5:265:61b6:56a6:b03d:28d6])
	(Authenticated sender: luke-jr)
	by zinan.dashjr.org (Postfix) with ESMTPSA id A1EA338A17C7;
	Thu, 24 Mar 2016 02:16:57 +0000 (UTC)
X-Hashcash: 1:25:160324:bitcoin-dev@lists.linuxfoundation.org::iBC2/37vkHJL/M=u:bU01E
X-Hashcash: 1:25:160324:dev@jonasschnelli.ch::NUIjFHu346GhVB3k:AD1P
From: Luke Dashjr <luke@dashjr.org>
To: bitcoin-dev@lists.linuxfoundation.org,
	Jonas Schnelli <dev@jonasschnelli.ch>
Date: Thu, 24 Mar 2016 02:16:55 +0000
User-Agent: KMail/1.13.7 (Linux/4.1.18-gentoo; KDE/4.14.8; x86_64; ; )
References: <56F2B51C.8000105@jonasschnelli.ch>
In-Reply-To: <56F2B51C.8000105@jonasschnelli.ch>
X-PGP-Key-Fingerprint: E463 A93F 5F31 17EE DE6C 7316 BD02 9424 21F4 889F
X-PGP-Key-ID: BD02942421F4889F
X-PGP-Keyserver: hkp://pgp.mit.edu
MIME-Version: 1.0
Content-Type: Text/Plain;
  charset="iso-8859-15"
Content-Transfer-Encoding: 7bit
Message-Id: <201603240216.56752.luke@dashjr.org>
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD
	autolearn=ham version=3.3.1
X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on
	smtp1.linux-foundation.org
X-Mailman-Approved-At: Thu, 24 Mar 2016 02:23:51 +0000
Subject: Re: [bitcoin-dev] p2p authentication and encryption BIPs
X-BeenThere: bitcoin-dev@lists.linuxfoundation.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Bitcoin Development Discussion <bitcoin-dev.lists.linuxfoundation.org>
List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/bitcoin-dev>,
	<mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=unsubscribe>
List-Archive: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/>
List-Post: <mailto:bitcoin-dev@lists.linuxfoundation.org>
List-Help: <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=help>
List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>,
	<mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=subscribe>
X-List-Received-Date: Thu, 24 Mar 2016 02:17:19 -0000

On Wednesday, March 23, 2016 3:24:12 PM Jonas Schnelli via bitcoin-dev wrote:
> I have just PRed a draft version of two BIPs I recently wrote.
> https://github.com/bitcoin/bips/pull/362

In the future, please submit BIP drafts to the mailing list for comment and 
initial peer review before opening a pull request (or requesting a BIP number 
assignment), per BIP 1.

> Each peer that supports p2p authentication, must provide two user editable
> databases (can be a simple record-per-line file).

As long as the format of these databases is not standardised, it seems 
inappropriate to define *any* of this implementation detail in a BIP.

> A peer can send an authenticate message by wrapping the desired message into
> an <code>auth</code>-message-wrapper to the remote peer.

How does a peer know what messages the other peer requires to be 
authenticated?

> 33bytes || identity-pubkey || comp.-pubkey || The identity pubkey of the
> requesting peer

Seems a waste to include this with every single [authenticated] message...

> 8bytes || auth-msg-id || int64 || up-counting auth-msg-id (0 to INT64MAX)

Is this required to persist across connections/restarts/possibly complete 
reinstalls?

Can the same auth-msg-id be used for multiple peers, so a message can be 
signed once and sent to all N peers?

> Responding peers must ignore (banning would lead to fingerprinting) the
> requesting peer after 5 unsuccessfully authentication tries to avoid
> resource attacks.

How does banning in this specific case enable fingerprinting as opposed to any 
other banning?

> The peers should display the identity-pubkey as a identity-address to the
> users, which is a base58-check encoded ripemd160(sha256) hash.

If this is going to become a general-purpose identity system, I think more is 
needed than a simple EC keypair. At the very least, it should probably use a 
HD chain and use a new key for every signature (notice you already have auth-
msg-id to use with this!).

> This proposal is backward compatible. Non supporting peers will ignore the
> <code>auth</code> message.

... and not process it at all? How is that backward compatible?

> Encrypting traffic between peers is already possible with VPN, tor, stunnel,
> curveCP or any other encryption mechanism on a deeper OSI level, however, 
> most mechanism are not practical for SPV or other DHCP/NAT environment and
> will require significant knowhow in how to setup a secure channel.

I don't see how Tor fails this criteria...

> The responding peer will set a session timeout time-interval. The default
> must be 1'800 seconds.

What default? Is the timeout field optional? Why not simply require it?

> This proposal is backward compatible. Non supporting peers will ignore the
> <code>enc*</code> messages.

How should the supporting peer handle the message being ignored?

Luke