From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Y0rN2-0007Yq-3b for bitcoin-development@lists.sourceforge.net; Tue, 16 Dec 2014 12:36:56 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of petertodd.org designates 62.13.149.101 as permitted sender) client-ip=62.13.149.101; envelope-from=pete@petertodd.org; helo=outmail149101.authsmtp.com; Received: from outmail149101.authsmtp.com ([62.13.149.101]) by sog-mx-2.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1Y0rN0-0004Jy-8v for bitcoin-development@lists.sourceforge.net; Tue, 16 Dec 2014 12:36:56 +0000 Received: from mail-c237.authsmtp.com (mail-c237.authsmtp.com [62.13.128.237]) by punt15.authsmtp.com (8.14.2/8.14.2/) with ESMTP id sBGCalOj014093; Tue, 16 Dec 2014 12:36:47 GMT Received: from savin.petertodd.org (75-119-251-161.dsl.teksavvy.com [75.119.251.161]) (authenticated bits=128) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id sBGCagYl087110 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Tue, 16 Dec 2014 12:36:45 GMT Date: Tue, 16 Dec 2014 07:36:42 -0500 From: Peter Todd To: Alex Mizrahi Message-ID: <20141216123642.GA19943@savin.petertodd.org> References: <54876653.4020403@certimix.com> <548769FA.5040406@bluematt.me> <417518B4-1E4D-4467-BC87-95C9EAF0C599@bitsofproof.com> <54880492.9060300@intersango.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0OAP2g/MAC+5xKAE" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Server-Quench: 32452cd9-8520-11e4-9f74-002590a135d3 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdwQUHFAXAgsB AmIbWlZeU1t7XWY7 bA9PbARUfEhLXhtr VklWR1pVCwQmQm52 dU9JO0VyfwJHeX4+ ZENhVnQVX0Z+cEQu FkdJHWgEZXphaTUb TUkOcAdJcANIexZF O1F8UScOLwdSbGoL NQ4vNDcwO3BTJTpY RgYVKF8UXXNDOzMm SB0OVTAuG0wDSG06 ZwcnJlNUF0YYM0N6 Llo9WRoAKRgVBEVZ ESMFCjJDIREGQWIz BBlXW1JWGz1UQCE0 X-Authentic-SMTP: 61633532353630.1024:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 75.119.251.161/587 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Spam-Score: -1.5 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain -0.0 SPF_PASS SPF: sender matches SPF record X-Headers-End: 1Y0rN0-0004Jy-8v Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Merged mining a side chain with proof of burn on parent chain X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 Dec 2014 12:36:56 -0000 --0OAP2g/MAC+5xKAE Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Dec 16, 2014 at 11:55:50AM +0200, Alex Mizrahi wrote: > Usually at this point people say "we assume that miners aren't going to > collude, otherwise even Bitcoin is not secure". > Well, this is BS. The fact that a pool can acquire more than 50% of total > hashpower was successfully demonstrated by ghash.io. > But the thing is, Bitcoin doesn't offer one a good way to attack the whol= e, > as there are powerful factors which will work against the attacker. > But this is not the case with sidechains (or any merged-mined chains, for > that matter). > And once you have a clear incentive, collusion is much more likely. +1 It's notable that blockstream hasn't published much if anything concrete on what exactly you'd use merge-mined sidechains for; they're even worse than Ethereum in that regard. > > Proof of Burn is a real cost for following the rules. > > >=20 > So what? As long as cost is less than revenue, it is OK. It's even better than that: if an attack does happen, the participants in the consensus system have an incentive to defend against it to maintain the value of their tokens. Proof-of-burn allows that defense to be in response to a threat, and essentially unlimited in size. So now any attacker knows that if they launch an attack in theory the response could be as strong as the value of the system itself. This can be improved upon with systems that allow the tokens to be burned, "internal" proof-of-burn. This suffers from "nothing-at-stake" vulnerabilities to an extent, OTOH within the context of the system it is a true sacrifice of value; probably not a big deal in a zookeyv-style block-DAG where multiple lines of history can be combined. Here the incentives of the defenders are even more strongly tipped towards burning their value to preserve the system, not unlike replace-by-fee-scorched-earth thinking. --=20 'peter'[:-1]@petertodd.org 00000000000000000e0c078667795abe21bfdebb913eba60cc7a625c732f0a89 --0OAP2g/MAC+5xKAE Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQGrBAEBCACVBQJUkCdWXhSAAAAAABUAQGJsb2NraGFzaEBiaXRjb2luLm9yZzAw MDAwMDAwMDAwMDAwMDAxMjRjOTFiMGIxYTE1ZWU2Njc0OTlmNzkzMTNhODQ5YzIx MmIyMWYyYzMwYjQ1NDgvFIAAAAAAFQARcGthLWFkZHJlc3NAZ251cGcub3JncGV0 ZUBwZXRlcnRvZC5vcmcACgkQJIFAPaXwkfsOcAgAjaNgy0PyWqR2yeXXqjuD5i+U syiGdJ3fw473PgTQRijBtmOPsBGy5/Z1/338GzxVcf0u6Yr9s5002pD09xcNfVJa kTYCDLEwulOHYnmsdUyN51SM+dQohCgzhtPISfyJiMTuzn/N+MSP/7AseSiquegh Y/I0vLaJboKmZZ+10xZyF0EfQQ5Ks3HpJwru5gwGxPL0NODGyTw/V9blpb06UqVt c0mHLJe9X0947N3CyOBX3ftXBfXIKeew3KOcLOsdGmCrinUEiQejiF024VwZtDys RXVP9qrZ+wJtYF/QJAOAgNQijNlynCHCqAjrO4Je0X5TXYRbzqjWAJvZQz5qZA== =Ka3f -----END PGP SIGNATURE----- --0OAP2g/MAC+5xKAE--