Technologies are generally provided for customizing operational aspects of a computing system associated with an interactive surface based on determining user identity through detection of one or more user identity attributes on the interactive surface. User identity attributes such as a finger orientation, a finger weight/pressure, a separation between fingers, a finger length, an arm orientation, a handedness, a posture, a DNA, or similar unique features of a user may be detected through an input device associated/integrated with the interactive surface, for example, by employing a camera-based Frustrated Total Internal Reflection (FTIR) system for capturing finger orientation through infrared light reflection, an overhead camera, or through Diffuse Illumination. Multiple attributes may be used to increase a confidence level in user identity determination in synchronous or asynchronous shared use of the interactive surface.