Abstract: A secure computing device (14) includes a secure processing section (30) having a tamper detection circuit (58) and a monotonic counter (68). The tamper detection circuit (58) detects an event which suggests that the trust associated with the secure processing section (30) may have been compromised. When such an event is detected, a security breach is declared and trusted software (38) is disabled. After a security breach is declared, the monotonic counter (68) may be reclaimed. The monotonic counter (68) provides a monotonic count value (70) that includes an LSB portion (80) and an MSB portion (82). The LSB portion (80) is obtained from a binary counter (72). The MSB portion (82) is obtained from a register (84) of independent one-time-programmable bits. The monotonic counter (68) is reclaimed by programming one of the one-time programmable bits to guarantee that future counting of the monotonic counter will be monotonic relative to all past counting.

Abstract: Timing circuitry may use control circuitry to control calibration circuitry to calibrate a counter so that an adder and a calibration period counter are not required. Concatenation circuitry may be used to concatenate a portion of the counter value and the calibration value to provide a calibrated value to the counter. The results from match circuitry may be used to provide status and control information to a calibration history bit and to an enable circuit. The counter may be an up counter or a down counter.

Abstract: A secure computing device (14) includes a secure processing section (30) having a tamper detection circuit (58) and a monotonic counter (68). The tamper detection circuit (58) detects an event which suggests that the trust associated with the secure processing section (30) may have been compromised. When such an event is detected, a security breach is declared and trusted software (38) is disabled. After a security breach is declared, the monotonic counter (68) may be reclaimed. The monotonic counter (68) provides a monotonic count value (70) that includes an LSB portion (80) and an MSB portion (82). The LSB portion (80) is obtained from a binary counter (72). The MSB portion (82) is obtained from a register (84) of independent one-time-programmable bits. The monotonic counter (68) is reclaimed by programming one of the one-time programmable bits to guarantee that future counting of the monotonic counter will be monotonic relative to all past counting.

Abstract: Timing circuitry may use control circuitry to control calibration circuitry to calibrate a counter so that an adder and a calibration period counter are not required. Concatenation circuitry may be used to concatenate a portion of the counter value and the calibration value to provide a calibrated value to the counter. The results from match circuitry may be used to provide status and control information to a calibration history bit and to an enable circuit. The counter may be an up counter or a down counter.