From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1VdpMs-0008KX-LB for bitcoin-development@lists.sourceforge.net; Tue, 05 Nov 2013 22:45:02 +0000 Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of zikula.org designates 209.85.212.179 as permitted sender) client-ip=209.85.212.179; envelope-from=drak@zikula.org; helo=mail-wi0-f179.google.com; Received: from mail-wi0-f179.google.com ([209.85.212.179]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1VdpMp-0004fJ-Km for bitcoin-development@lists.sourceforge.net; Tue, 05 Nov 2013 22:45:01 +0000 Received: by mail-wi0-f179.google.com with SMTP id hm4so2854002wib.0 for ; Tue, 05 Nov 2013 14:44:53 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-type; bh=UfGk+tJoht8DhzVzdiqFzch3lUlO6fNnPNoKtQpowso=; b=nD84evRaTdQ14RarCM3mI2guyZnVB/blZ775h5UElzSfzZOYeAdNyAu9XfPZlPTFrB 5XCah9qfVzZM7S/gzSDvYGFKhyIHl4ra39XvcvnHMzzmvwBLaDC58YBvmSp5QOyczw6j 1KU2Y/0sJs+W2QKJ6pXB8V06+rBRawfRHBv/nXw1LdoygjbqsHivdbqk0RXzfI4k7O5e Jtgt3BDqmpKFAYbyr4NnCetgIkglHKxNqM3FX3bpu+BzIXZhrW/JhZwdhP9qIG7oZE3F ene+st9EVahaaNpfJWjh0xdb8BDF8Ra3ypG55aQsYDXqXen6Xm3pCP9uTYybhCnor18l sW+A== X-Gm-Message-State: ALoCoQnbYXy030X5pDz0ZVtjgoV5y0AyNfBLFc9nU1AyQP5INXlo6FrHRGcDEqodaEr+NLoKwVBP X-Received: by 10.180.198.5 with SMTP id iy5mr18567115wic.45.1383689747409; Tue, 05 Nov 2013 14:15:47 -0800 (PST) MIME-Version: 1.0 Received: by 10.194.93.105 with HTTP; Tue, 5 Nov 2013 14:15:27 -0800 (PST) In-Reply-To: References: From: Drak Date: Tue, 5 Nov 2013 22:15:27 +0000 Message-ID: To: bitcoin-development@lists.sourceforge.net Content-Type: multipart/alternative; boundary=047d7b624e2adfc61004ea755fe5 X-Spam-Score: -0.5 (/) 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 0.0 URIBL_BLOCKED ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [URIs: safe-mail.net] 1.0 HTML_MESSAGE BODY: HTML included in message X-Headers-End: 1VdpMp-0004fJ-Km Subject: Re: [Bitcoin-development] Possible Solution To SM Attack 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, 05 Nov 2013 22:45:02 -0000 --047d7b624e2adfc61004ea755fe5 Content-Type: text/plain; charset=UTF-8 On 5 November 2013 20:51, wrote: > Possible Solution: > If N amount of blocks built of the same previous block are received within > a time frame of T mine on the block with the lowest hash. > > Logic: > In order for Alice to pull of this attack she not only has to propagate > her blocks first she must also ensure her blocks are of the smallest hash. > > Alice would now have to decrease her target to pull of this attack. Since > she has a lower target it will take her longer to find a valid block > negating her time advantage. If I understand the issue properly, this seems like a pretty elegant solution: if two blocks are broadcast within a certain period of eachother, chose the lower target. That's a provable fair way of randomly choosing the winning block and would seem like a pretty simply patch. Drak --047d7b624e2adfc61004ea755fe5 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On 5 November 2013 20:51,=C2=A0<colj@safe-mail.net&g= t;=C2=A0wrote:
Possible Solution:
If N amount of blocks built of the same previous bloc= k are received within a time frame of T mine on the block with the lowest h= ash.

Logic:
In order for Alice to pull of this attack she not onl= y has to propagate her blocks first she must also ensure her blocks are of = the smallest hash.

Alice would now have to decrease her target to pull of this attack. Sin= ce she has a lower target it will take her longer to find a valid block neg= ating her time advantage.

If I understand t= he issue properly, this seems like a pretty elegant solution: if two blocks= are broadcast within a certain period of eachother, chose the lower target= . That's a provable fair way of randomly choosing the winning block and= would seem like a pretty simply patch.

Drak
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