Biometric technology uses human physical attributes as locks and keys, making it particularly suitable for access control systems on the buildings of large organisations. Using biometrics for security and identificationrequires meeting two challenges: they must be cheap enough and sufficiently simple to be used by ordinary users. Furthermore, for enhanced security, these biometric access control systemsshould combine two or more types of authentication, such as coupling fingerprints with key codes or passwords to provide greater trust that who is logging in is only who is expected to do so.