CryptoAuthentication™ hardware design is both flexible and protected. The devices support a wide supply voltage range of 2 to 5.5 Volts and a communications voltage range of 1.8 to 5.5 Volts. They consume very little power with typical sleep current of less than 10 nanoamps and a maximum current draw of less than 150 nanoamps. Power is also saved by means of a watchdog timer, which induces sleep after one second. To correctly protect a crypto engine device from tampering and attack, physical design techniques are employed. Microchip's designers implemented a series of physical barriers and countermeasures including a full serpentine shield over the entire device. This “active shield” pattern detects any break or short from a physical incursion. No probe or test pads are present so that attackers cannot measure various parameters of the devices operation to try to detect patterns. Internal memories are fully encrypted and power supplies have tamper detection so that attackers cannot take measurements.