Rohos Mini Drive
This is best tool that can help you to get your USB protected by password. You don't need to have administrator rights to work with this tool. Its free version allows making password protected partition of upto 2GB in size on your USB drive. This is portable and you can use it without installation on any computer. This is reason Rohos don't require administrator rights. Oh I forgot to tell you about its encryption; it got AES 256 bit encryption.
You have option to define custom size for the partition that Rohos Mini Drive will make on your USB flash drive. As free version only supports 2GB so you have to buy its full version if you want to increase size.
It is another powerful solution for protecting your external drives or USB flash drives. It prevents unauthorized access to your data when you use it to add password to your data. It supports all portable devices like USB flash drive, thumb drive or any external drive.
Once your USB drive is password protected you don't have to worry about any data loss and unauthorized access.
Just open up USB security and you'll see all your external drives connected to your device in its explorer window just select drive you want to be password protected and add password to it.
This is another best program that can help you for protecting your files by adding password to it. It is also a portable like Rohos Mini Drive described above. Like Rohos it also got on-the-fly AES 256 bit encryption.
But it is different in its working procedure. You have to lock a file and unlock it to work with it. After working you have to lock it again if you want it to be password protected again.
You have to give password every time you lock or unlock a file. You have to remember password that you used when you locked a file.