Secrets in the computer require the same protection as secrets on paper. Information can usually be recovered from a computer hard drive even after the file has been deleted or erased by the computer user. It has been estimated that about a third of the average hard drive contains information that has been "deleted" but is still recoverable.1
Computers on which classified information is prepared must be kept in facilities that meet specified physical security requirements for processing classified information. If necessary to prepare classified information in a non-secure environment, use a typewriter or a removable hard drive or laptop that is secured in a safe when not in use.
Check with your security office concerning rules for traveling with a laptop on which classified or other sensitive information has been prepared. Laptop computers are a particular concern owing to their vulnerability to theft.