manual

encryption key which used a complex arrangement of spools and wires to
encode messages. The ability to send secure coded messages gave the German
navy a strategic advantage. U-boats used Enigma machines to conceal
messages containing convoy sightings and their periodic positions. Without the
Enigma, these messages could not be kept secret since they were constantly
intercepted by the Allies.
The British were finally able to decrypt the Enigma messages, changing the
course of the war to the Allies' advantage during the Battle of the Atlantic. This
example shows the importance of keeping your information secure. The Allies
were able to decode the messages because the Enigma machine used an
inadequately complex encryption method, and due to a parts of the encryption
key being revealed through carelessness and, once, the capture of an Enigma
machine from a German U-boat.
Modern encryption works by the same principles as the Enigma machine, though
thankfully newer methods encrypt data so well that it cannot be decrypted without
the key. To close or tighten the security gap inherent in portable USB Flash
drives, we must use encryption. There are a variety of encryption types and
methods of applying them. This whitepaper will discuss several USB drive data
encryption strategies.
Encryption Schemes
There are three methods to encrypt digital data on USB drives: manual, semi-
transparent and transparent.
Manual Encryption
With manual encryption, a user manually selects each file to encrypt or decrypt.
Consequently, the user has to remember to run the encryption process for each
file they want to protect. This method requires only basic encryption software on
the user's computer. This method is the least safe because the user can forget to
encrypt their files
[4]
.
Semi-transparent Encryption
In semi-transparent encryption, encoding operations are done before or after
access is made to confidential data. For example, a user can configure
encryption software to decrypt their files when their computer boots up and
encrypt them when the computer shuts down. A USB Flash drive might employ
semi-transparent encryption by decrypting the drive's files when the drive is