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 3DB55E37 for ; Tue, 6 Aug 2019 13:07:31 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from geekbox.info (mx01.geekbox.info [95.216.118.16]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 392BE8AB for ; Tue, 6 Aug 2019 13:07:29 +0000 (UTC) Received: from [192.168.1.69] (122-58-55-184-vdsl.sparkbb.co.nz [122.58.55.184]) (Authenticated sender: leo) by geekbox.info (Postfix) with ESMTPSA id 494777003B1 for ; Tue, 6 Aug 2019 13:07:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=leowandersleb.de; s=mail; t=1565096847; bh=gqpnHcvRUlSKywHWXsZ2xsE1TaBpWTsBaPb0x8///gw=; h=Subject:To:References:From:Date:In-Reply-To; b=engjZuVcHaqw69x3my/wsjCJ1CdylcL3a/Z3MRI5AJgrxHH4hwbvSLh/4nQCqCn3e iJoaPqWX2lWxMhWoMdLqwsNShTEEmFKJQ3WR9JPQY9NkWfOwfhgYPOhUwPY3hTRJCE I+FJSw6Tnlm9z+Ds3D3FUKE0FPJ+eqF12t7ZKBr8= To: bitcoin-dev@lists.linuxfoundation.org References: <985792b1-e7aa-677b-a7a1-6a5f672da884@riseup.net> <94534006-D560-4C90-9D5D-A3A64B698518@gmail.com> <20190726143738.0be561da@simplexum.com> <3c328312-2bdd-60d9-7425-8db620d09abb@riseup.net> <20190731205018.10ed4302@simplexum.com> <20190802145057.7b81c597@simplexum.com> <3a9a9277-130d-fbb2-fa51-6119a2242812@LeoWandersleb.de> <7a42fc7c-2e89-deae-12d6-8f7f5a46b915@riseup.net> From: Leo Wandersleb Openpgp: id=FAE4D5168E9EF9F104AA1B2D6B9A1F0CB7C20812 Autocrypt: addr=leo@LeoWandersleb.de; prefer-encrypt=mutual; keydata= mQENBE3ePdoBCADZmTvPyledh9wmNRE+i5k7dUmegSmBpe1kMgzlt3nxwzyE6l3wzT9wen8E clmA4ZCLn77DjxF3Dg9X0sRio9No5r4u6luI0CzM7axvTi+5DWU25b+JGGdhKTMkyfyKBZdT 4xvjLzW9tT7upUuAh9nTcz9MBZS3vhKB1SqiBUdYqj33+2erIQzaYMIZ/crR6FbgDT5dI3gg 2YKJn4rdFy9saA0qngoDPkyU9u5TYtFk8zOreQrFXmXpLiptoxRolF9tqHyn51H4uV8ggIGc xJWRW/i2vBFHSM6ZD7PceWCRU5ehf3h/wat1xtn/H7AB+wcywkYrdg1TLifftwcKYBlzABEB AAG0JUxlbyBXYW5kZXJzbGViIDxMZW9ATGVvV2FuZGVyc2xlYi5kZT6JATgEEwECACIFAk3e PdoCGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGuaHwy3wggSrqQH/Amh6+kYnIUM 8X5yicpXd37h/Nqnrs6KIE0nYCZe03tkQytndbWXmf2pBth6CEzqrS+wivU7L8dPdiFQtdEW dDe8bjJ993TsVSyYrPHv549vD4DbjtB8WS7KEkMhhl+uVaC07YXNwOTAkshv4l3G2ll6dmBn LDeF8kSU+DZ1eNzUYHjuUcQYl0XAK5wE7rVpzZUlR0Z5bKNm8QmUPgrZPu6cVRZ6tOD0EMR6 3dcGI5x0fB35gEUasgNYxQ/g2arh66Pg45olKT1bTcrTJYrE8IePElSCIFDrzrZMhStY3TbQ qI3T0vsFGzEeU9M6LmKV8aii4g8o7af0kr4vYS3Nsp65AQ0ETd492gEIAMnahwe+MNliWgpF B+UfrwzfgiLjtizH307HYB67THS4h2+MoBJUAqrV7CQkZ8kMYLBl4D+hvxrXDYte6wTb0kcY X4NTGof8EDBPxUERYJlWbTbLccbA8d3ia++aTtqd9yRHobK8AO4R22cslYV/nQChHc+1/NFV 8V1O67U7XpnxQMUzYIhhvVcUwj+8bw/F3zPzS03PWnDv+gmwHt63w72Dth+P0F93/rI+OiEA kC/7//1ngQ7auqOeWVdqR8Z1s7tI4kxsVkJfqj3wVu+qaso8FpjNGs888xH8xhgXlll8APWj V9Rl3GtpRTdobzNh58jUfGmHh5bcRrYTrtldDwkAEQEAAYkBHwQYAQIACQUCTd492gIbDAAK CRBrmh8Mt8IIEi3MB/0UlpEORi7qBOH9egn/8E9fXj3QGpmQ7IAvzvLjkp3cArerBhObhGJ+ lZ679/9KZ4FxWLDStzGJH3thQstZjcUZzLwTP1sNdY+uPkvOqrzclfPK13z5hJhORD8W0brB UptTvyZthIxNIbY4uSbrvaAJmcPFi3cdKOjZz9XyH8AAxXcWGUjQuqxEc0GuM8h8asaUJesB bE4J+HPZXcAOC3D+qIqvM438Nbb8Pu7yYWrdq5kmbDMg2nPHXUOOovEsXWBGjWEiXWVUei75 5Fumqg5mz4P8/Ry3DwZBuHN3Op77gXogvyeE/B5O6dZzWWpSqBIS6MQcLD1divwi/2vNS4c4 Message-ID: Date: Wed, 7 Aug 2019 01:07:19 +1200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <7a42fc7c-2e89-deae-12d6-8f7f5a46b915@riseup.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Tue, 06 Aug 2019 16:57:13 +0000 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: Tue, 06 Aug 2019 13:07:31 -0000 On 8/6/19 10:27 PM, Chris Belcher via bitcoin-dev wrote: > I think this is absolutely wrong, because sybil attackers give up some > fee income. Here is a worked example: > > Let's say the sybil attacker is operating the top 5 most valuable maker > bots. If this attacker has X coins they would split them equally into 5, > so each maker has X/5 coins and their bond is worth (X^5)^2 = X^2/25, > with a total of 5 bots the fee income would be proportional to 5*X^2/25 > = X^2/5. However if an honest maker had X coins they could create a > single bond which would be worth simply X^2 with a fee income > proportional to X^2. So the honest maker has a fee income higher by a > factor of 5 than the sybil attacker. The sybil attacker must take a 5x > hit to their fee income in order to sybil attack. This is the crucial > effect of the V^2 term. > > The V^2 term is important, it just has the downside of incentivizing > renting of coins. If we can make that impossible then the problem would > go away. To show how this argument is wrong, think about the market being split between 100 makers, each making 1% of the fees. By your argument, by colluding, they could make far more than 100% of the fees. Every cartel of makers pooling their bonds beating the odds can't be the goal. And again, bonds are just a cost of business. If a $10/month in bonds (paid to a guy to sign with his UTXOs or interest for BTCs lent or ...) leaves me with zero fees, a $100/month with $1k in fees and $10k/month with $40k in fees, then there might be a $1000/month barrier to entry for this market but there are enough people with $10k available to enter the market and drive the fees (earned per maker) down such that the barrier to entry increases even further. In the end, only the holders of the 20 biggest bonds will get meaningful business and the rest will lose their investment or just not bother being makers. And the sibyl attackers again are the ones that put up the necessary funds with most ease of them all.