Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753040AbaLGMwL (ORCPT ); Sun, 7 Dec 2014 07:52:11 -0500 Received: from helcar.apana.org.au ([209.40.204.226]:33372 "EHLO helcar.apana.org.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752365AbaLGMwJ (ORCPT ); Sun, 7 Dec 2014 07:52:09 -0500 Date: Sun, 7 Dec 2014 20:51:57 +0800 From: Herbert Xu To: George Spelvin Cc: dborkman@redhat.com, hannes@stressinduktion.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, tgraf@suug.ch, "David S. Miller" , "Theodore Ts'o" Subject: Re: Where exactly will arch_fast_hash be used Message-ID: <20141207125157.GA9745@gondor.apana.org.au> References: <20141207092828.GA8623@gondor.apana.org.au> <20141207100252.6707.qmail@ns.horizon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141207100252.6707.qmail@ns.horizon.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 07, 2014 at 05:02:52AM -0500, George Spelvin wrote: > > How does this implicate the low bits specifically? If you can easily deduce the pre-images that make the last bit of the hash even or odd, then you've just cut your search space for collisions by half. The real killer is that you can do this without knowing what the secret is. Our entire scheme is dependent on using the secret to defeat would-be attackers. If CRC does not make effective use of the secret, then we're essentially naked against attackers. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/