Given an input item (N bytes), I'm looking for a function that will map this to an output (still N bytes). The function should have the following qualities:
- It should be 1-to-1 so that all inputs map to some output and so that no two inputs map to the same output.
- Given an output element it should be difficult to guess the input that lead to that output, even when the mapping is completely known.
Does such a function exist? Where can I learn more?