Security Real-Time Clock Input Masking for Low-Power Tamper Protection
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Solution Overview
Problem
Real time clock generators are vulnerable to tampering, particularly through repetitive alterations of the supply voltage, which can cause them to reset or become stuck, and existing monitoring methods are power-consuming, especially during low power modes.
Innovation Solution
A device with a voltage supply unit connected to an integrated circuit that includes a security real time clock generator, a masking unit to isolate inputs when the voltage supply monitor is disabled, and a method to enable the monitor and stop isolation, allowing for efficient protection against tampering while managing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage supply monitor is used to monitor the voltage supply unit continuously, then the security real time clock generator is protected from tampering, but the power consumption increases especially during low power modes
Solution Approach 1:
The voltage supply monitor is dynamically controlled to be enabled or disabled based on the operational state of the device. During low power modes, the monitor is disabled to reduce power consumption, while during active modes it is enabled to provide protection. This dynamic adjustment resolves the contradiction between continuous monitoring and power consumption.
Solution Approach 2:
The masking unit is configured to automatically mask the input signal when the voltage supply monitor is disabled, and to unmask it when the monitor is enabled. This preliminary preparation of the masking state ensures that when the monitor is re-enabled after a low power mode, the input is immediately protected, preventing any tampering attempts that occurred during the monitor's disabled state.
2Use of energy by moving object
If the voltage supply monitor is disabled during low power modes, then power consumption is reduced, but the protection against tampering is weakened
Solution Approach 1:
The masking unit acts as an intermediary between the voltage supply monitor and the real time clock generator input. When the monitor is disabled, the masking unit blocks the input signal, preventing tampering. When the monitor is enabled, the masking is removed to allow normal operation. This intermediary mechanism ensures that even when the monitor is disabled to save power, the system remains protected through the masking unit.
3Reliability
If the masking unit continuously masks the input, then the real time clock generator is protected from tampering, but the normal operation is interrupted when monitoring is needed
Solution Approach 1:
The masking unit dynamically adjusts its masking state based on the operational requirements. It masks the input when the voltage supply monitor is disabled (during low power modes) to prevent tampering, and unmaskes the input when the monitor is enabled (during active modes) to allow normal operation. This dynamic control resolves the contradiction between continuous protection and normal operation.
Data Source
AI summary
A device having protection capabilities, the device includes a voltage supply unit that is connected to an integrated circuit and provides a supply voltage to the integrated circuit; wherein the integrated circuit includes: a security real time clock generator that includes an input; a masking unit that is connected to the input, wherein the masking unit isolates the input when a voltage supply monitor is disabled; and wherein the voltage supply monitor monitors the voltage supply unit and wherein a change in a level of supply voltage affects a level of a signal provided to the input.