Modern computing systems provide various methods for user authentication. A common authentication technique only has a password requirement: The user enters his or her user identifier, and then a secret password that only the user knows. This is referred to as single-factor authentication, since it only relies on what the user knows. Some applications or devices allow a user to remember an identifier and password that has been successfully authenticated so that the user does not have to repeatedly enter the identifier/password for each authentication attempt. While stored credentials are convenient for the user, there is a risk of unauthorized use of the application/device by another party. The risk of unauthorized use of stored credentials is even greater when the credentials are stored on a mobile device.