A system for encrypting data comprising a computer configured to encrypt a plurality of data entries using at least one encryption algorithm and a system memory, wherein the computer is configured to use different keys with the encryption algorithm(s) for each data entry and the system is configured to store in the system memory or transmit for storage in an external memory the encrypted data corresponding to each entry along with an identifier corresponding to at least part of the key used to encrypt that entry, such that when decrypting a data entry in the system or external memory the associated identifier can be used to locate at least part of the correct key.