12. The system of claim 8 , wherein the one or more processors are configured to execute the instructions to cause the system to perform further operations comprising: determining a sub key generated by the system that is different than the one or more encryption keys, wherein the encrypted word frequencies and the encrypted word position identifiers are determined based on the sub key.
8. A system comprising: a non-transitory computer-readable medium comprising instructions; one or more processors configured to execute the instructions to cause the system to perform operations comprising: (a) obtaining one or more first documents, wherein each first document comprises one or more first word sets each of which comprises one or more first words, and at least one first document comprises a plurality of first word sets at least one of which comprises a plurality of first words; (b) determining dictionary data, wherein determining the dictionary data comprises determining, using each first document, a word-level encryption and a set-level encryption based on one or more encryption keys, wherein: determining the set-level encryption comprises determining a plurality of encrypted word sets each of which is an encryption of a corresponding one of the first word sets, each first word set corresponding to an encrypted word set; and determining the word-level encryption comprises determining a plurality of encrypted words each of which is an encryption of a corresponding one of the first words, each first word corresponding to an encrypted word; wherein the dictionary data comprises the encrypted words and the encrypted word sets; determining index data in one or more storage networks, wherein the index data comprises encrypted word frequencies and encrypted word position identifiers based on the encrypted words; determining an encryption of one or more search terms received by a user interface of the system based on the one or more encryption keys; and identifying one or more of the first documents in the one or more storage networks based on a search performed with the one or more encrypted search terms and at least one of the encrypted word frequencies and the encrypted word position identifiers.