From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 0E3C6C016F for ; Wed, 10 Jun 2020 12:32:20 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id E564F25432 for ; Wed, 10 Jun 2020 12:32:19 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id RlqPYqUL20sp for ; Wed, 10 Jun 2020 12:32:18 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-lj1-f172.google.com (mail-lj1-f172.google.com [209.85.208.172]) by silver.osuosl.org (Postfix) with ESMTPS id 7CE27253A7 for ; Wed, 10 Jun 2020 12:32:18 +0000 (UTC) Received: by mail-lj1-f172.google.com with SMTP id a9so2243176ljn.6 for ; Wed, 10 Jun 2020 05:32:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=pmhE4DKJina/kXCWAkBuYgjUm1IqW/HR9n2stS6gt5Q=; b=Z6DhuNEcnwyM8Rf2sakV8Kj1uiYJAlJc6CKGbOzXAYflkTPzUvm+29ferseUSNg2Dk Rie6PspuNAhA0tiA8WruSl45faRXLfQIBKw6M1a/lfJhWqVl3+mGkstqsRC0i5W/O2WZ czov2gHK/AxRlg7waZdmQyGTd8I5hYBCuXViG8mHButxhqQqnJ6ETCuwpQObGsSTnCrF iKNOfQ0UQjXpdiqsDfs66G1Jkskj+/Vdnha1vFsW5O8euk0hdQTQTs1HIRGUmXUckxkr qyp3knQODLaunhkMoLyuSIQ+aCekCQhSoNc6fkjUwG0xtNiJpdO0API84uUjbmnImJW9 x45Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=pmhE4DKJina/kXCWAkBuYgjUm1IqW/HR9n2stS6gt5Q=; b=VIcDzhq6fCQGJv2bJh/Q3xFH/g/PT5s1nSWu8ze3WT4b1wdY0AEmS+5FkFBTiWuPUz LkttDljkXtDA3y4vezS0FDswtx0h5E5t4UAcfVd9tx3sNu13K3Z9Wifr8BRXMZICeiC9 eGRxxhLAmhfpCzxQ7IEI242FSWU5kD34zwO58MxXOsWtm6Lfl6tDygZf/3rf4OE7gV5w ogHNHKe0FbwIUTZI868Q6sERrGBO6736RlGD9pDVl3vF5szz2tLClrthRQiNUlWUsAl1 laN/YDdNYaZMmcvLkEGaABmhAS5kOYF5Zws68YkQybrfi9BRTyzv+bShLY7Sz0oBi3GX spvw== X-Gm-Message-State: AOAM530IjXP8dVOuImSurDm5vyUMJm/UzIgQTaIjI5QlbSbc8p6L/dCJ LAEM08dSWywOA/qw0XS6/X7Ro+L++ENz9PF2qAmXyA19M3SpNg== X-Google-Smtp-Source: ABdhPJyfV/rKe3axg7zhLVaSk6kAEH+Aw6lcdHBMB2wav28OnlXMKeLHR1Z24nx6R2u1WVu7s1JZkjiAv/uC0Q761S4= X-Received: by 2002:a2e:b60c:: with SMTP id r12mr1733162ljn.316.1591792336014; Wed, 10 Jun 2020 05:32:16 -0700 (PDT) MIME-Version: 1.0 From: nopara73 Date: Wed, 10 Jun 2020 14:32:05 +0200 Message-ID: To: Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary="000000000000be907505a7ba0849" X-Mailman-Approved-At: Wed, 10 Jun 2020 13:40:10 +0000 Subject: [bitcoin-dev] Tainting, CoinJoin, PayJoin, CoinSwap X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Jun 2020 12:32:20 -0000 --000000000000be907505a7ba0849 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable The problem with CoinJoins is that desire for privacy is explicitly signalled by them, so adversaries can consider them "suspicious." PayJoin and CoinSwap solve this problem, because they are unnoticeable. I think this logic doesn't stand for scrutiny. >From here on let's use the terminology of a typical adversary: there are 3 kinds of coin histories: "clean", "dirty" and "suspicious". The aftermath of you using a "dirty" coin is knocks on your door. You using a "suspicious" coin is uncomfortable questions and you using a "clean" coin is seamless transfer. In scenario 1, you start out with a "clean" history. By using CoinJoins you make your new coin's history "suspicious" so you have no incentive to CoinJoin. By using CoinSwap/PayJoin your new coin can be either "clean" or "dirty". What would a "clean" coin owner prefer more? Take the risk of knocking on the door or answering uncomfortable questions? In scenario 2, you start out with a "dirty" history. By using CoinJoins you make your new coin's history "suspicious" so you have an incentive to CoinJoin. By using CoinSwap/PayJoin your new coin can either be "clean" or "dirty". What would a "dirty" coin owner prefer more? And here's an insight: you may get knocks on your door for a dirty coin that you have nothing to do with. And you can prove this fact to the adversary, but by doing so, you'll also expose that you started out with a "dirty" coin to begin with and now the adversary becomes interested in you for a different reason. You can also examine things assuming full adoption of PJ/CS vs full adoption of CJ, but you'll see that full adoption of any of these solves the tainting issue. So my current conclusion is that PJ/CS does not only not solve the taint problem, it just alters it and ultimately very similar problems arise for the users. Maybe the goal of unobservable privacy is a fallacy in this context as it is based on the assumption that desiring privacy is suspicious, so you want to hide the fact that you desire privacy. And the solution to the taint issue is either protocol change or social change (decent adoption.) PS.: Please try to keep the conversation to the Taint Issue as this email of mine isn't supposed to be discussing general pros and cons of various privacy techniques. Any thoughts? --=20 Best, =C3=81d=C3=A1m --000000000000be907505a7ba0849 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
The problem with CoinJoins is that desire for privacy is e= xplicitly signalled by them, so adversaries can consider them "suspici= ous." PayJoin and CoinSwap solve this problem, because they are unnoti= ceable. I think this logic doesn't stand for scrutiny.

From here on let's use the terminology of a typical adversary: there= are 3 kinds of coin histories: "clean", "dirty" and &q= uot;suspicious".
The aftermath of you using a "dirty" coi= n is knocks on your door. You using a "suspicious" coin is uncomf= ortable questions and you using a "clean" coin is seamless transf= er.

In scenario 1, you start out with a "clea= n" history. By using CoinJoins you make your new coin's history &q= uot;suspicious" so you have no incentive to CoinJoin. By using CoinSwa= p/PayJoin your new coin can be either "clean" or "dirty"= ;. What would a "clean" coin owner prefer more? Take the risk of = knocking on the door or answering uncomfortable questions?

In scenar= io 2, you start out with a "dirty"=20 history.=20 By using CoinJoins you make your new coin's history "suspicious&qu= ot; so you have an incentive to CoinJoin. By using CoinSwap/PayJoin your new coin can either be "clean" or= "dirty".=20 What would a "dirty" coin owner prefer more? And here's an in= sight: you may get knocks on your door for a dirty coin that you have nothi= ng to do with. And you can prove this fact to the adversary, but by doing s= o, you'll also expose that you started out with a "dirty" coi= n to begin with and now the=20 adversary becomes interested in you for a different reason.

Y= ou can also examine things assuming full adoption of PJ/CS vs full adoption= of CJ, but you'll see that full adoption of any of these solves the ta= inting issue.

So my current conclusion is that PJ/CS does= not only not solve the taint problem, it just alters it and ultimately ver= y similar problems arise for the users. Maybe the goal of unobservable priv= acy is a fallacy in this context=C2=A0as it is based on the assumption that= desiring privacy is suspicious, so you want to hide the fact that you desi= re privacy. And the solution to the taint issue is either protocol change o= r social change (decent adoption.)

PS.: Please try to keep the conve= rsation to the Taint Issue as this email of mine isn't supposed to be d= iscussing general pros and cons of various privacy techniques.

Any thoughts?

--
Best,
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