In article <Xns### [at] 204213191226>, "Rafal 'Raf256' Maj"
<raf### [at] raf256com> wrote:

> 1. sin(x)*power  + clock + y+z+rand(seed1) // input
> 2. sin(x)*power+clock+y+z+rand(seed1)      // no spaces
> 3. sin(x)*3.0+0.1+y+z+rand(777)            // constants - ready
>
> now show me formula that will result in _differnet_ pattern and that will
> give _same_ hash as "sin(x)*3.0+0.1+y+z+rand(777)"

What you are asking for is the most trivial demonstration:

Assume you have a hash function which gives you 2^128 possible hash values.
Now try to create a hash over all 17 byte sequences.  This would be 2^136
different bit pattern.  The result is that you would have at least (2^136 -
2^128) duplicate hash value, and probably more depending on the quality of
your hash function.  It is very simple and trivial to show that every hash
function has this problem as long as it has a finite range and is supposed
to hash something with an infinite range (functions can be very complex as
you pointed out yourself).  Being able to find a duplicate is a matter of
time, not principle.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

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