Is it possible to determine the original data used to generate a specific hash?

It is generally impossible to determine the original data from a given hash. Hash functions (e.g., SHA-256, MD5) are designed for one-way transformation of data: they convert input data into a fixed-length hash, but do not allow for the original data to be reconstructed unambiguously.

This is because a hash is a compressed representation, and different input data sets can produce the same hash (collisions). Therefore, reverse transformation (from hash to original data) is not feasible in practice.

If you need to verify whether data matches a hash, you typically compare the hash of the data with the given hash.