Windows 7 includes a program called BitLocker for encrypting any drive in 2-3 simple steps. Just follow the steps below… and you can secure you files inside USB flash drive but setting a password and encrypting data contents.
How to Use Windows 7 BitLocker to Password Protect USB, Potable DrivesStep 1 : Insert your USB drive, or any portable hard drive and Right click on it in explorer. Now choose “Turn on Bitlocker…“
Step 2 : A small window will appear and prompt you for choosing a password that will be required while opening it later. Proceed by clicking the “Next“.
Step 3 : Bitlocker will create and save a recovery key in your PC in case you forget password. Simply choose the first option to save the recovery key in a text file in a secure place.
Step 4 : Wait for few minutes while it will be encrypting the portable drive slowly.Depends upon the data volume in your removable drive.
Step 5 : Once done, plug-off and insert the USB drive again to see the encryption in action. BitLocker encryption will be automatically run up and prompt you for putting the password. You have to put the password for only once for accessing the data in it until you plug off.
Very useful for locking USB drives with password and encrypting it to keep it secure.
The Above Artical posted by Mr. Tushar Patel (