A method begins with a processing module obtaining data to store and determining whether substantially similar data to the data is stored. When the substantially similar data is not stored, the method continues with the processing module generating a first encryption key based on the data, encoding the first encryption key into encoded data slices in accordance with an error coding dispersal storage function, and storing the encoded data slices in a dispersed storage network (DSN) memory. The method continues with the processing module encrypting the data using an encryption key of the substantially similar data in accordance with an encryption function to produce encrypted data, compressing the encrypted data in accordance with a compression function to produce compressed data, storing the compressed data when the substantially similar data is stored.