Properties of MD5

Hello,

as I know MD5 is an algorithm that avoids collissions and documents with
little difference result in a MD5 hash with a big difference and two
completely different documents may result the same MD5 sum.

My problem is that I want to use MD5 in my software but MD5 only offers a
128 bit hash string as result. I want to take only the first n bits of this
hash value. Now my question: Is the algorithm then still behaving
identically. Of course I get more collisions with fewer bits but I want to
know if the distribution is likewise the 128 bit version. Do you know any
ressources where I can get some detailed information about this.

Anyway: Is there a good reason why MD5 uses exactly 128 bit as output and
512 bit blocks while encoding?

Thanks a lot
Andreas
Received on Thu Sep 29 21:39:32 2005