Re: Added hashes.

On Mon, 12 Dec 2005 22:32:03 -0500, "John E. Hadstate"
<jh113355@hotmail.com> wrote:

>
>"Juuso Hukkanen" <juuso_12_2003@tele3d.net> wrote in message
>news:e1rrp1p8t0rb3qv53bq43nh0qa2cl1c2io@4ax.com...
>> On Sat, 10 Dec 2005 19:55:22 -0500, "John E. Hadstate"
>> <jh113355@hotmail.com> wrote:
>>
>>>No. By hashing the file twice with two independent hashes
>>>and then XORing the two results, you have created a third
>>>hash for which the probability of collisions is just as
>>>computable as it is for either hash alone. It is the
>>>nature
>>>of a hash to have collisions.
>>
>> No, that can't be true.
>
>
>I believe you are mistaken. I don't think you even read
>what I wrote. The paragraph above is so obvious to anyone
>who's thought about this for more than 15 minutes that I am
>appalled that you would respond with such nonsense.

You are partially right, I took couple of words from your reply and
responded to those, but I believe you agree / will agree with me on
comments to those words :)

Naturally the byte wise combination does not create a third-hash which
could have more entropy states (<->collision resistance) than
available in either of the original two. What I say is that in a
combination of one Perfectly good-hash and an extremely bad-hash, the
faults in bad-hash do not influence the quality of third-hash as much
as indicated with:

>>>...computable as it is for either hash alone

ohh, You answered exactly to that what I try to 'claim' in next

>I will agree that XORing two hashes together in effect
>causes one to encipher the other, thus possibly hiding
>weaknesses in either, which I think is what you were trying
>to say in the part I snipped.

Damit, did I try to say something else :D

What I claim is that a combination of one _PERFECTLY GOOD_ hash with
one equally long but terrible bad-hash, results a third hash, where
the faults caused by bad-hash are hidden PERFECTLY.

I motivate my claim with comparing such _PERFECTLY GOOD_ hash being
equally good random as a true random source is in the production of
one-time-pads. In addition the terrible- bad hash could be compared to
(low entropy) plain text.--->
1) When OTP is combined with message, message gets hidden PERFECTLY
2) When a PERFECTLY good hash is combined with bad hash, badness of
bad-hash is hidden (Shanonially) PERFECTLY

****************************
QUESTION:
Can you confirm that being logically correct or not?
****************************
>Notice, however, that I am
>not advancing (and I do not subscribe to) the notion that
>the XOR of two hashes produces a hash that is more immune to
>attack than either constituent.

I have absolutely no problem with that. The resulting third hash can
not derive such improvement which is not present in original hashes.

I admit to have written that unnecessary strongly,
>> No, that can't be true.
, in order to get your attention and into answering the imperceptible
marked question (- sorry for that). This is important since I intend
to use such third-hash
        (Whirlpool +SHA-512= t3d-hash)
among other, in creating a (proof of concept) cipher with more
flexibility and slowness, than is in morale of an average drug dealer.

Kind Regards
Juuso Hukkanen
(to reply by e-mail set addresses month and year to correct)
Received on Fri Dec 23 20:10:01 2005