MD5 is 1=>1?

[Roger Bryner <bryner@atlas.chem.utah.edu>]

On Mon, 4 Jul 1994 nobody@shell.portal.com wrote:
> Now if I have entered a phrase with EXACTLY 128 bits of entropy, 
> hypothetically, is that enough to have flushed the padding or 
> whatever out of the pipeline?
I have had this question also, has it been shown that the transformation 
of 128bit words through md5 is *theoretically* invertable, as if it is 
not, iterating it 1024 times could actually make you *LOOSE* entropy.
(say it was a random transformation, it would not contain each of the 128 
bit outputs, ie some inputs would map to the same output.)

I am not aware of any such result.

Roger.