Dual-Timer Timekeeping for Secure Power-Off Time Integrity
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Solution Overview
Problem
Mobile devices face challenges in ensuring the integrity and security of time information, which can be altered or tampered with due to power outages or malicious attacks, compromising security-based operations.
Innovation Solution
The electronic device incorporates a nonvolatile memory, a power management integrated circuit, and an application processor to generate and manage time information independently of power supply, using a security processor to ensure integrity by storing and updating time data securely, even in system-off states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time information is generated using a timer dependent on power supply, then the device can operate normally during power-on state, but the time information may be altered or falsified when power supply is interrupted
Solution Approach 1:
The time management function is segmented into two independent components: a first timer in the power management integrated circuit that operates independently of power supply interruptions, and a second timer in the application processor that operates during normal power-on state. This segmentation allows each timer to fulfill its specific role without compromising the integrity of time information.
Solution Approach 2:
A memory device serves as an intermediary to store time data including time values from both the first timer and second timer. This intermediary storage mechanism ensures that time information is preserved accurately across power transitions and can be verified for integrity, preventing tampering while maintaining system operation.
2Reliability
If a single timer is used for time generation, then the device structure remains simple, but the time information cannot be verified for integrity after power interruptions
Solution Approach 1:
The system implements a feedback mechanism where the first timer continuously provides time information to the memory device even during power-off states. When power is restored, the second timer compares its time values with the stored first timer values to verify integrity. This feedback loop ensures that any tampering or falsification of time information can be detected.
Solution Approach 2:
The first timer in the power management integrated circuit performs preliminary time generation and storage actions before power interruptions occur. By pre-storing accurate time information in the memory device, the system establishes a reference baseline that can be used to verify the integrity of time information after power restoration, preventing post-interruption falsification.
3Duration of action of stationary object
If time information is stored in volatile memory, then the system operates efficiently with fast access, but the time data is lost during system-off state
Solution Approach 1:
The system merges volatile memory (for fast access during operation) with nonvolatile memory characteristics by storing time data in a memory device that retains information across power cycles. The memory device is configured to preserve time information from the first timer during system-off states while maintaining fast access capabilities during operation, effectively combining the advantages of both memory types.
Solution Approach 2:
The memory device changes its operational parameters based on power state: during power-on state, it operates with fast write/read speeds for real-time time management; during power-off state, it transitions to a retention mode that preserves time data without requiring continuous power. This parameter change allows the system to maintain time data persistence without sacrificing operational efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures the integrity and security of time information by maintaining accurate time data across power interruptions, preventing tampering and ensuring reliable security operations.
Implementation Method 1
a power capacitor configured to provide auxiliary power based on pre-charged electric charges in response to occurrence of a system-off state in which supply power received from a power source is interrupted
Data Source
AI summary
Provided are an electronic device and an operating method thereof. The electronic device includes a nonvolatile memory; a power management integrated circuit configured to generate operating power based on supply power received from a power source, and generate first time information independent of the supply power; and an application processor configured to receive the operating power, generate second time information, obtain, based on the generation of the operating power being interrupted, the first time information, and output, to the nonvolatile memory, time data including the first time information and the second time information, a write command, and an address.