From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 156F4DC6 for ; Wed, 7 Aug 2019 11:20:50 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-40133.protonmail.ch (mail-40133.protonmail.ch [185.70.40.133]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 243E87D2 for ; Wed, 7 Aug 2019 11:20:47 +0000 (UTC) Date: Wed, 07 Aug 2019 11:20:38 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=default; t=1565176845; bh=JSPVXV46I8szQ0bZDH3YhSe3OZzvYGEiCJDwACGunBc=; h=Date:To:From:Cc:Reply-To:Subject:In-Reply-To:References: Feedback-ID:From; b=RCeUQjOMkls98qyHXpQ7jMyPbuyV2qnvs1to0ARObrkgm7Xa39ziTcZ/w6X2KTrrj IE8rMberb66Q+9dcLgimS5ftIntzZNWwbVUs2vMVHXDiFh5cWDgb13q90eI6fAoQ9i MY8ehdBihV9p9cIKHuHJ3+nLIUBpjvRpFcaB/oQw= To: Chris Belcher From: ZmnSCPxj Reply-To: ZmnSCPxj Message-ID: <6neYGtuk8rPzYt5-qWJDrGiWAfC9aRUzlmjb6bg9JV_D59UFPfuvU7w0cSIbJ4c_YzbPcwk7O7ZDnu7ML_CvkBcQNPigS6RVdzFDAuk7Eu8=@protonmail.com> In-Reply-To: <113a68d9-6c8c-3bf2-b337-9b87c5fd1db7@riseup.net> References: <985792b1-e7aa-677b-a7a1-6a5f672da884@riseup.net> <20190731205018.10ed4302@simplexum.com> <20190802145057.7b81c597@simplexum.com> <20190807015541.3d8aa849@simplexum.com> <20190807023742.73750ba3@simplexum.com> <113a68d9-6c8c-3bf2-b337-9b87c5fd1db7@riseup.net> Feedback-ID: el4j0RWPRERue64lIQeq9Y2FP-mdB86tFqjmrJyEPR9VAtMovPEo9tvgA0CrTsSHJeeyPXqnoAu6DN-R04uJUg==:Ext:ProtonMail MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, FROM_LOCAL_NOVOWEL, RCVD_IN_DNSWL_LOW 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: Wed, 07 Aug 2019 12:04:18 +0000 Cc: Bitcoin Protocol Discussion Subject: Re: [bitcoin-dev] Improving JoinMarket's resistance to sybil attacks using fidelity bonds X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 07 Aug 2019 11:20:50 -0000 Good morning Chris, > Also, as described in my other email > (https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2019-August/0172= 18.html > starting " > Let's say the sybil attacker...") the superlinear V^2 term is essential > to the resistance of the fidelity bond system to sybil attacks. At the cost of *greatly* strengthening aggregation. Suppose there is currently many makers, all with roughly-equal bonds. Suppose I were to approach two of these makers, and offer to aggregate thei= r bonds. The combined bond would, because of the V^2 term, have 4 times the weight o= f the other makers. Thus, approximately I can earn a little below 4 times what one other maker = does. I offer 1.5x what one maker does to both of those makers and keep a little = below 0.5x to myself. So: 1. I earn without putting any of my money into bonds. I just need starting capital to pre-pay for the rents. 2. I get to learn a little below 4x more CoinJoins than other makers. This increases my earnings further since I can sell this privacy inform= ation, and I also get an advantage compared to other non-aggregating spies. It seems to me not to fix the root issue, i.e. makers who make for the purp= ose of gathering privacy information, even if it might fix sybil attackers. Regards, ZmnSCPxj