A digital signature collection and authentication system includes an ink pen having an ultrasonic transmitter that transmits ultrasonic energy to a plurality of ultrasonic receivers. A computer triangulates the location of the pen versus time to generate the signature shape, and to generate velocity and acceleration data. The pen also includes a pressure sensitive tip to record pressure applied to the pen tip. The pen also includes a higher frequency burst transmitter useful to generate a time reference, and to transmit the pressure information. The computer packetizes the shape, velocity, acceleration, and pressure data with a time stamp and an IP address or phone number, encrypts the packet and sends it to a host computer for authentication.