Apologies, I phrased that poorly. I meant the characteristic that makes it a hash function is producing a fixed size output. It may not be that important for

Apologies, I phrased that poorly. I meant the characteristic that makes it a hash function is producing a fixed size output. It may not be that important for some contexts, but without that characteristic it's not a hashing function. Conversely, I can have a function that isn't one way, but produces a fixed size output. Granted, it's not going to be that useful, but it's still a hashing function. If I have a one-way function that doesn't produce a fixed size output, it's not a hashing function.