From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1WXwrx-0004Sn-21 for bitcoin-development@lists.sourceforge.net; Wed, 09 Apr 2014 18:05:05 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of petertodd.org designates 62.13.148.95 as permitted sender) client-ip=62.13.148.95; envelope-from=pete@petertodd.org; helo=outmail148095.authsmtp.com; Received: from outmail148095.authsmtp.com ([62.13.148.95]) by sog-mx-3.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1WXwrv-0007yt-K7 for bitcoin-development@lists.sourceforge.net; Wed, 09 Apr 2014 18:05:05 +0000 Received: from mail-c235.authsmtp.com (mail-c235.authsmtp.com [62.13.128.235]) by punt18.authsmtp.com (8.14.2/8.14.2/) with ESMTP id s39I4usa022162; Wed, 9 Apr 2014 19:04:56 +0100 (BST) Received: from [25.121.248.92] ([24.114.49.14]) (authenticated bits=0) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id s39I4qDR046437 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 9 Apr 2014 19:04:53 +0100 (BST) User-Agent: K-9 Mail for Android In-Reply-To: <0509477C-89F9-47C7-8820-29ACAD4A4A8E@bitsofproof.com> References: <53456B99.9010207@monetize.io> <00b77560-d7ed-4ed4-a4e5-eb1f00467a06@email.android.com> <0509477C-89F9-47C7-8820-29ACAD4A4A8E@bitsofproof.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Peter Todd Date: Wed, 09 Apr 2014 14:04:46 -0400 To: Tamas Blummer Message-ID: <1fa234ec-9dd4-45de-8ac8-ca20a158c344@email.android.com> X-Server-Quench: 74178956-c011-11e3-b802-002590a15da7 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdgsUGUUGAgsB AmIbWl1eUFl7XGc7 aQ5PbARZfE5HQQRu T0xPR01TWkZrCGUF R2p8Uh10cwZBNn9x ZUBmEHdfXUNyfEN7 Xx1UFGwbZGY1a31N WEBaagNUcgZDfk5E bwQuUz1vNG8XDQg5 AwQ0PjZ0MThBJSBS WgQAK04nCWwKAjU7 RhYOWDQpWEcMTCY8 NRs7LFJUGUEdPw08 NkFpYmomUgAbDglT A1ol X-Authentic-SMTP: 61633532353630.1023:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 24.114.49.14/465 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by punt18.authsmtp.com id s39I4usa022162 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: 1WXwrv-0007yt-K7 Cc: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] Bitcoind-in-background mode for SPV wallets 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: Wed, 09 Apr 2014 18:05:05 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 9 April 2014 13:50:03 GMT-04:00, Tamas Blummer = wrote: >Block header has to be available in SPV and also in an UTXO only >storing core node, so why not serve it if bandwith allows. > >Serving any additional information like known peer adresses or known >full blocks is certainly beneficial and should be offered if at hand. Big security advantages too. For instance if an attacker hacks, say, 10=E2= =84=85 of hashing power the next step for them to attack SPV clients is t= o try to Sybil attack them so they won't find out about the longer chain.= The fewer providers of block chain data there are out there the easier t= hat attack is - just simultaneously DoS a bunch of nodes, perhaps by a lo= w-bandwidth exploit like the bloom io or division by zero DoS attacks. Th= is is much harder to pull off if every SPV client is passing around block= headers. Similarly by passing around full blocks the attacker has a harder time kn= ocking other miners off the network. Regardless of whether or not a miner= 's peers are fully validating chain data they still have the data they ne= ed to mine the next block and thus extend the longest correct chain. -----BEGIN PGP SIGNATURE----- Version: APG v1.1.1 iQFQBAEBCgA6BQJTRYu+MxxQZXRlciBUb2RkIChsb3cgc2VjdXJpdHkga2V5KSA8 cGV0ZUBwZXRlcnRvZGQub3JnPgAKCRAZnIM7qOfwheuQCADUyClLOLP1xpG1000l uzcfPTZuIXTpzOAmYHKs/MSb6mph/Shsu0/94eW7npQNSVeZC8wQQZ1oFQ9j1GJc SKViYJfn5yMdNvMkaWazhC0r3jxxF0AI7oy2KlnSjasfczfOQuYICJadTCwvUHrb GrKVDbgsKNzZYYKn86vF4hsLwtJN4moeqX85TYN1DC7//7hgNywA73Xt2/gdwfqe LOsD4nS7mUQObQd6TcLwXDDNEGTrdS572jdYH5sykwZjPH+wqwcm2WKTnIULsJR0 OwGUi505AKJJnLcEmZ/kGbCmKB+xJ5kExjlExtcUPrJlc+xqubhnnGCMjBiGCXSY kYCK =3DHXRZ -----END PGP SIGNATURE-----