Data storage systems are disclosed for automatically generating encryption rules based on a set of training files that are known to include sensitive information. The system may use a number of heuristic algorithms to generate one or more encryption rules for determining whether a file includes sensitive information. Further, the system may apply the heuristic algorithms to the content of the files, as determined by using natural language processing algorithms, to generate the encryption rules. Moreover, systems are disclosed that are capable of automatically determining whether to encrypt a file based on the generated encryption rules. The content of the file may be determined using natural language processing algorithms and then the encryption rules may be applied to the content of the file to determine whether to encrypt the file.