Concept of hashing a group of data and validating if a value exists within the group
It sounds like you're describing a Bloom filter.

Note that they're designed to allow false positives (but not false negatives). They can be good to quickly check whether a value might be in a certain set worthy of a more computationally-expensive check. Imagine that you are scanning a large body of text word by word, there is a set of key words you're looking for, and there are more key words than fit in RAM. You can create a bloom filter out of all of the key words that fits in RAM. Whenever you find a word that passes the bloom filter, that means the word might be a key word, so you can then double-check the word against your list of key words on disk. This saves you from having to access the disk for every word you scan.