Suppose I have the following hash function: $\newcommand{\md}[1]{\text{md#1}} \newcommand{\H}{\text{H}}$
$$\H(x, y) = \md{5}(x) \oplus \md{4}(y)$$
How can I prove it's collision proof?
I tried to say "lets assume we have an oracle which know how to find a collision/pre image of $\H$" and find an algorithm to find $\md5$ collision. I didn't manage to find such algorithm.
How can it be proved?
