In this work, we propose the first PIN number based authentication system, which can be deployed on ubiquitous surfaces, leveraging physical vibration signals. The proposed system aims to integrate PIN number, behavioral and physiological characteristics together to provide enhanced security. Different from the existing passwordbased approaches, the proposed system builds upon a touch sensing technique using vibration signals that can operate on any solid surface. In this poster, we explore the feasibility of using vibration signals for ubiquitous user authentication and develop algorithms that identify fine-grained finger inputs with different password secrets (e.g., PIN sequences). We build a prototype using a vibration transceiver that can be attached to any surface (e.g., a door or a desk) easily. Our experiments in office environments with multiple users demonstrate that we can achieve high authentication accuracy with a low false negative rate.