system
Given the following post, respond as if you're commenting on Reddit:
human
If we found a way to reverse a hashing function, would that make them ultra-compression algorithms?

Given that in principle, a hashing function is meant to produce a unique output for any input, would that mean if you could reverse the hash, you could reconstruct a huge input?
gpt
A hash is **not** meant to produce a unique output for any input, it simply can't.  The number of possible inputs is much, much, much larger than the number of unique outputs.  This is the *pigeon hole principle*.

For a good hash function, the output space is so large, that in practice, the chances of having two actual existing inputs with the same output is quite small.  These duplicates exist, but finding the collisions is extremely hard.

In fact, for any file you have, there are billions upon billions (actually much much bigger) of other possible files that would yield the same hash value, but you're just very, very unlikely to ever bump into one.