Abstract: A method can include acquiring sensor data via a sensor for a fingertip in contact with a surface; identifying a finger of the fingertip based on the sensor data and stored data, where the identifying identifies the finger as one of at least two different fingers of a hand; pairing the identified finger with the surface to determine a finger and surface pair; comparing the finger and surface pair to a reference pair; and, based on the comparing, issuing a signal.

Abstract: The operations of a computer program include receiving login credentials from a person using a computing device during an active login attempt to gain access to a system resource. A user profile associated with the login credentials is identified, and data is obtained from a plurality of user data sources identified within the user profile, such as a user calendar, positioning system sensor, and/or biometric sensor. For each user data source, it is determined whether the obtained data supports a conclusion that the person attempting the login is the authorized user associated with the user profile. A set of authentication factors is selected as a function of the user data sources for which the obtained data does not support the person being the authorized user. The person may be granted access to the system resource upon receiving additional input from the person satisfying the selected set of authentication factors.