From mboxrd@z Thu Jan 1 00:00:00 1970 From: Edward Shishkin Subject: Re: Congratulations! we have got hash function screwed up Date: Thu, 20 Jan 2005 16:18:40 +0300 Message-ID: <41EFAFB0.2000606@namesys.com> References: <77912E9FD42896419D1CEF15E1C397A58AFCF1@london.jaguarfreightservices.local> <20041230235911.4911a20c.hihone@bigpond.net.au> <41D42F93.9060107@namesys.com> <2f4958ff050118131714f5411c@mail.gmail.com> <41EE859D.3020305@namesys.com> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <41EE859D.3020305@namesys.com> List-Id: Content-Type: text/plain; charset="windows-1252"; format="flowed" To: Hans Reiser Cc: =?UTF-8?B?R3J6ZWdvcnogSmHFm2tpZXdpY3o=?= , Matthias Andree , hihone@bigpond.net.au, reiserfs-list@namesys.com Hans Reiser wrote: > Grzegorz Ja=C5=9Bkiewicz wrote: > >> On Thu, 30 Dec 2004 08:40:51 -0800, Hans Reiser =20 >> wrote: >> =20 >> >>> Fixing hash collisions in V3 to do them the way V4 does them would >>> create more bugs and user disruption than the current bug we have all >>> lived with for 5 years until now. If someone thinks it is a small >>> change to fix it, send me a patch. Better by far to fix bugs in V4, >>> which is pretty stable these days. >>> =20 >> >> >> As I understeand, tea hash is based on tea (tiny encryption aglo), >> which was the cause of xbox-linux sucess, and few others. >> Pleas consider updating it to use xxtea algo. I know, it won't be >> backward compatbile, but well. >> Where is about all the others, I don't use them, and for me tea is the >> only resonable hash to use on systems where I have very much great >> number of files per directory (to name it, Maildirs). >> Never had such problem myself, every hash function has a weaknes. >> Nothing new. But providing another, much stronger hash, or correct tea >> hash to use xxtea, would be something good indeed. >> >> =20 >> > Edward, please look into whether we should use xxtea in Reiser4, and=20 > make a recommendation to me. We aren't changing V3, it is stable and=20 > I want to leave it that way. > > Hans > > I found that: 1. xxtea is a correction to the Blocktea algorithm against the attack=20 not related to the original tea or xtea. 2. xtea is an upgrade of tea algo which eliminates two minor weakness of=20 the last one related to key attacks, and not related to the collisions of tea hash (for each name tea hash=20 uses ciphering by the key constructed by this name). So imho it doesn't make sense to upgrade the core rounds used in tea=20 hash. Any objections? Edward.