1. A method for execution by a dispersed storage and task (DST) execution unit that includes a hardware processor, the method comprises: receiving a slice pre-image request from a computing device via a network, wherein the slice pre-image request indicates a data slice, a requesting entity, and a plurality of storage units; generating a data pre-image by performing a pre-image function on the data slice based on the plurality of storage units; and generating an encrypted data pre-image for transmission to the computing device by performing an encryption function on the data pre-image based on a key associated with the requesting entity; wherein the computing device receives a plurality of encrypted data pre-images from a plurality of storage units that includes the DST execution unit for transmission to the requesting entity for decoding; wherein the requesting entity receives a plurality of storage unit identifiers corresponding to the plurality of storage units from the computing device, and wherein the requesting entity decodes the plurality of encrypted data pre-images by utilizing a plurality of unique keys, each associated with one of the plurality of storage units; and wherein the requesting entity receives a sum of the encrypted data pre-images from the computing device, and wherein decoding includes subtracting each of the plurality of unique keys from the sum of the encrypted data pre-images.