Abstract: A data transfer device for storing data to a removable data storage item, wherein data are received as records and encrypted by the data transfer device prior to storage. The data transfer device encrypts a first portion of the records using a first encryption key and a second portion of the records using a second encryption key. The encrypted records are then stored to the removable data storage item as a plurality of data blocks, each data block comprising one or more encrypted records, wherein records in a respective data block are encrypted using only a respective one of the encryption keys.