1. A data storage system comprising: a computing system comprising one or more hardware processors programmed to: determine a set of file portions from a plurality of training files, at least some of the set of file portions comprising content designated as sensitive information, each of the file portions comprising a subset of content of at least one file from the plurality of training files; generate a prospective encryption rule for addition to a set of available encryption rules based at least in part on an aggregated set of the file portions, the aggregated set of the file portions including file portions that appear in more than one file from the plurality of training files; determine a number of files from the plurality of training files identified for encryption by performance of the prospective encryption rule; and when the number of files identified for encryption does not satisfy a threshold number of files, iteratively modify the prospective encryption rule until the threshold number of files of the plurality of training files are identified for encryption by performance of the modified prospective encryption rule, and store the modified prospective encryption rule at a non-volatile repository.