Apparatus and methods of operating a memory include storing a value of an attribute of a feature vector to a pair of memory cells by programming each of the memory cells to a respective data state of three or more data states, searching for an exact match to a particular value of the attribute by applying respective voltage levels to control gates of the memory cells to activate both memory cells only when the value of the attribute is the particular value, and searching for an inexact match to the particular value of the attribute by applying respective voltage levels to control gates of the memory cells to activate both memory cells when the value of the attribute is within a range of possible values of the attribute including the particular value.

Embodiments of the invention broadly described, introduce systems and methods for enabling the searching of encrypted data. One embodiment of the invention discloses a method for generating a searchable encrypted database. The method comprises receiving a plurality of sensitive data records comprising personal information of different users, identifying one or more searchable fields for the sensitive data records, wherein each searchable field is associated with a subset of the personal information for a user, generating a searchable field index for each of the one or more searchable fields, and encrypting the sensitive data records using a database encryption key.