In some examples, a data backup system may comprise a removable data storage item, wherein a manufacturer of the removable data storage item creates and stores an encryption key on the removable data storage item before the removable data storage item is shipped to an end user; a tamper-evident packaging including the removable data storage item, wherein the removable data storage item comprises a decryption key stored on a memory device accessible by disturbing the tamper-evident packaging; and a data transfer device to receive the removable data storage item, read the encryption key from the removable data storage item, encrypt backup data using the encryption key, and store the encrypted backup data on the removable data storage item.