Current authentication schemes suffer from many weaknesses. Textual passwords are widely used; however users tend to choose meaningful words from dictionaries. This makes textual passwords easy to break and vulnerable to dictionary or brute force attacks. Many available graphical passwords face lack of space. Smart cards or tokens can be lost or are prone to theft. Many biometric authentications have been proposed but users tend to resist using them because of their intrusiveness on their privacy. The three-dimensional (3-D) password is a multifactor authentication scheme i. e. it combines most of the existing authentication schemes such as textual passwords, graphical passwords, and biometrics into a single virtual three-dimensional environment. Users navigate through this virtual environment and interact with the objects placed in it. The combination of all the actions and inputs towards the virtual three-dimensional environment constructs the user's 3D password. Simple approach for a secure authentication is to use one or more of the above mentioned authentication techniques in combination for multi-level authentication, so that, the probability of breaking such a password is reduced to a large extent. Hence multi-level authentication technique can be used for ensuring a more stringent authentication.

Three dimensional four dimensional Biometrics Virtual environment USB drives