An integrated circuit that includes operational circuitry and message digest generation circuitry coupled to the operational circuitry, a method for testing an integrated circuit including message digest generation circuitry, and a system including an integrated circuit (which includes message digest generation circuitry) and at least one external device coupled to the integrated circuit. The message digest generation circuitry is coupled and configured to generate at least one digest of at least one message, where each message is indicative of at least one aspect of the integrated circuit's state. For example, a message can be a sequence of voltages or logic levels sampled at a specific sequence of nodes of operational circuitry of the integrated circuit.