Return-Path: <alicexbt@protonmail.com>
Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133])
 by lists.linuxfoundation.org (Postfix) with ESMTP id 8BB71C0032
 for <bitcoin-dev@lists.linuxfoundation.org>;
 Thu,  6 Jul 2023 16:23:10 +0000 (UTC)
Received: from localhost (localhost [127.0.0.1])
 by smtp2.osuosl.org (Postfix) with ESMTP id 59CE54156F
 for <bitcoin-dev@lists.linuxfoundation.org>;
 Thu,  6 Jul 2023 16:23:10 +0000 (UTC)
DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 59CE54156F
Authentication-Results: smtp2.osuosl.org;
 dkim=pass (2048-bit key) header.d=protonmail.com header.i=@protonmail.com
 header.a=rsa-sha256 header.s=protonmail3 header.b=xg+p+mod
X-Virus-Scanned: amavisd-new at osuosl.org
X-Spam-Flag: NO
X-Spam-Score: -0.699
X-Spam-Level: 
X-Spam-Status: No, score=-0.699 tagged_above=-999 required=5
 tests=[BAYES_05=-0.5, DKIM_SIGNED=0.1, DKIM_VALID=-0.1,
 DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001,
 RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001,
 SPF_HELO_PASS=-0.001, SPF_PASS=-0.001]
 autolearn=ham autolearn_force=no
Received: from smtp2.osuosl.org ([127.0.0.1])
 by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024)
 with ESMTP id H78i_gB09hXN
 for <bitcoin-dev@lists.linuxfoundation.org>;
 Thu,  6 Jul 2023 16:23:09 +0000 (UTC)
X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0
DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org E2BC440B34
Received: from mail-4324.protonmail.ch (mail-4324.protonmail.ch [185.70.43.24])
 by smtp2.osuosl.org (Postfix) with ESMTPS id E2BC440B34
 for <bitcoin-dev@lists.linuxfoundation.org>;
 Thu,  6 Jul 2023 16:23:08 +0000 (UTC)
Date: Thu, 06 Jul 2023 16:22:44 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com;
 s=protonmail3; t=1688660581; x=1688919781;
 bh=MSFBOE4DLC0YIdmdbiftOAL7Eempz5O26i77RvjSZo0=;
 h=Date:To:From:Subject:Message-ID:Feedback-ID:From:To:Cc:Date:
 Subject:Reply-To:Feedback-ID:Message-ID:BIMI-Selector;
 b=xg+p+modt2Hdt/xBjxkgOJUbuoko2Dt5oisj9V84yl9oEBtJPzohYEJEd18fqizS1
 MdFjjJnpIIuZoaWZrfdCvpDv9Zq+7k74gRvSPjMQclgTqu5Yv7aMd0R4PSzcVnLrX9
 6/GxRIRYnzYpSQt37MQGnlH4BjN6/x0XRIFnplTuyh/PYGeZvNiaqghlg5CX5ZkpdP
 T9P6sgnkcEDBA04S9NocB/6r+B7/QnSapSgYbJNX9oUviE1CQMycufCRsRlc3UxomG
 ZT236/Ev3+r2ZB/DkGAReGjvipKTwVSZNX1mg0q5Ne+OK+LpCb1uHrzvbLMEvpclIK
 KeCGRF1XfhiUA==
To: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: alicexbt <alicexbt@protonmail.com>
Message-ID: <Ga2AELVMhRn2JlAC1-85LivVhcBhXzsf5ypHXMt_lg9RpwKTxeRxIRr8g8UHUihvxIVNKua6FIGRCjkt4CuNcDtZy2MetpOucpZYoKPW5sw=@protonmail.com>
Feedback-ID: 40602938:user:proton
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
X-Mailman-Approved-At: Thu, 06 Jul 2023 16:44:26 +0000
Subject: [bitcoin-dev] Denial of Service using Package Relay
X-BeenThere: bitcoin-dev@lists.linuxfoundation.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Bitcoin Protocol 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, 06 Jul 2023 16:23:10 -0000

Hi Bitcoin Developers,

I think its possible to use [package relay][0] for DoS attack in coinjoin. =
A few other projects could also be affected by packages. Since its a propos=
al that adds new P2P messages, transaction relay etc. its as important as a=
ny soft fork. Let me know if I am missing something.

Consider there are 2 coinjoin implementations: A and B

1) Register input in A
2) Double spend same input with zero fee to your own address
3) Register unconfirmed UTXO from 2 in B
4) B relays a package in which coinjoin transaction (child) pays for 2 (par=
ent)

Users and coinjoin implementation B, both are incentivized to attack in thi=
s case.

Attacker could also use a different approach and register same input in A, =
B although there are some tradeoffs:

- If input gets included in a coinjoin transaction broadcasted by A, there =
is nothing much B can do about it. RBF with multiple users isn't easy and c=
ostly.
- Implementation with less users participating in a round would have an adv=
antage.

[0]: https://gist.github.com/sdaftuar/8756699bfcad4d3806ba9f3396d4e66a


/dev/fd0
floppy disk guy

Sent with Proton Mail secure email.