1. A method for secure data retrieval in a dispersed storage network (DSN), the method comprises: retrieving, by a first computing device of the DSN, a decode threshold number of encrypted encoded data slices of a set of encrypted encoded data slices from at least some storage units of a set storage units of the DSN, wherein the set of storage units encrypt a set of encoded data slices using a set of encryption keys to produce the set of encrypted encoded data slices, and wherein a first encoded data slice of the set of encoded data slices is encrypted based on a first encryption key of the set of encryption keys to produce a first encrypted encoded data slice of the set of encrypted encoded data slices; generating, by the first computing device, a decoding matrix based on pillar numbers of the decode threshold number of encrypted encoded data slices and an encoding matrix; dispersed storage error decoding, by the first computing device, the decode threshold number of encrypted encoded data slices based on the decoding matrix to produce an encrypted data segment; sending, by the first computing device, the encrypted data segment and the pillar numbers to a second computing device of the DSN; identifying, by the second computing device, a particular subset of encryption keys of the set of encryption keys based on the pillar numbers; and decrypting, by the second computing device, the encrypted data segment based on the particular subset of encryption keys.