Re: Congratulations! we have got hash function screwed up

[Edward Shishkin <edward@namesys.com>]

Hans Reiser wrote:

> Grzegorz Jaśkiewicz wrote:
>
>> On Thu, 30 Dec 2004 08:40:51 -0800, Hans Reiser <reiser@namesys.com> 
>> wrote:
>>  
>>
>>> 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.
>>>   
>>
>>
>> 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.
>>
>>  
>>
> Edward, please look into whether we should use xxtea in Reiser4, and 
> make a recommendation to me.  We aren't changing V3, it is stable and 
> I want to leave it that way.
>
> Hans
>
>
I found that:
1. xxtea is a correction to the Blocktea algorithm against the attack 
not related to the original tea or xtea.
2. xtea is an upgrade of tea algo which eliminates two minor weakness of 
the last one related to key attacks,
and not related to the collisions of tea hash (for each name tea hash 
uses ciphering by the key constructed
by  this name).
So imho it doesn't make sense to upgrade the core rounds used in tea 
hash. Any objections?

Edward.