A self-authenticating electrocardiography and physiological sensor monitor is provided. An electrode patch includes an elongated strip and electrodes exposed on each end. A receptacle is adhered to the elongated strip and includes electrical pads. Circuit traces are electrically coupled to the electrocardiographic electrodes and the electrical pads. A monitor recorder having a sealed housing is adapted to be secured into the receptacle. Circuitry within the housing includes a microcontroller with a private key. A copy of the private key is stored on the patch. Self-authentication is performed each time the monitor recorder is inserted into a new patch by challenging the patch using a code hashed with the private key and by receiving a response from the patch in reply to the challenge. A front end circuit senses electrocardiographic signals via electrodes on the patch when the response received by the microcontroller is positive, until the electrode patch expires.
