Telerobotic systems are used to perform critical tasks in sensitive environments. The security of these systems is of paramount importance, because compromising them can result in significant harm. In this paper, we attempt to address threats leading to illegitimate access to telerobotic devices. We conducted an experiment in which users explored a scene using a GeoMagic Phantom Omni haptic device. The scene provided only limited visual feedback, and required users to interact with it by primarily relying on haptic feedback. We recorded how 32 users interacted with the haptic device over a total of 180 sessions. Our results show that haptic signals collected during a session can be successfully used to distinguish between users. As a result, telerobotic operators can be authenticated transparently throughout a session (i.e., continuously) by relying on haptic measurements alone.