US Patent 9679165 Encryption/decryption for data storage system with snapshot capability

A method for managing access to encrypted data of a data storage system storing snapshot data, a snapshot providing a previous point-in-time copy of data in a volume of the data storage system, wherein the data storage system utilizes changing encryption keys for write data. For each snapshot, the method stores at least one decryption key identifier for each decryption key corresponding to an encryption key utilized to encrypt data written to a volume since a previous snapshot was committed to disk, and associates the at least one decryption key identifier with the snapshot. A key table associating decryption key identifiers with corresponding decryption keys is provided, and based on the key table and the at least one decryption key identifier associated with the snapshot, one or more decryption keys required for accessing encrypted data associated with the snapshot are determined. Decryption key identifiers may be stored in snapshot metadata.