The same principle applies to the storage media such as diskettes or hard disks. For example, diskettes containing proprietary information should be marked in eye-readable format such as a sticker and secured safely when not in use. The markings must be retained on the media until the sensitive information has been declassified, downgraded, or removed from the media. The security of proprietary information during storage and transmission depends on proper encryption. Encryption is a way to render a text unreadable once you have applied a key and an algorithm to a readable text.
Decryption is exactly the opposite.
Several encryption packages are available on the market, even some shareware, programs you can try and purchase if you like them, can do the task perfectly well. Classified information or designated information of a very sensitive nature should not be sent via any electronic media if the information is not protected by encryption. If the information is extremely sensitive, a division might decide to use appropriate measures to encrypt every file stored on their personal computers and on the network servers. If faxes or telephones are to be used for such transmission, use of secure units is recommended. A secure fax machine is available at 580 Booth street on the second floor in the emergency operations centre.