RTC Anti-Rollback Protection via Checkpoint Validation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Real-Time Clock (RTC) systems in System-On-Chip (SoC) devices are vulnerable to tampering through 'rollback' attacks, where the time is set to a past date, compromising security policies and software revisions that rely on an increasing time.
Innovation Solution
An application-specific integrated circuit (ASIC) with an integrated anti-rollback protection mechanism, featuring a Real-Time Clock (RTC) block, a checkpoint memory block, and set RTC logic, which only allows updates to new dates and times if they are in the future relative to a stored active date/time checkpoint, using non-volatile memory to maintain checkpoints even when power is interrupted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the RTC allows time to be set freely, then the ease of operation is improved, but the security against rollback attacks deteriorates
Solution Approach 1:
The patent implements a checkpoint mechanism that records the current RTC time before allowing any time setting operation. This preliminary action creates a reference point that prevents future rollback attacks, as any attempt to set the time to a previous value can be detected and rejected.
Solution Approach 2:
The system continuously monitors the RTC time and compares it against stored checkpoints. When a time setting attempt is made, the system provides feedback by validating whether the new time is greater than the checkpoint time, thereby preventing rollback attacks while allowing legitimate forward time adjustments.
2Reliability
If the RTC maintains continuous operation with battery backup, then the reliability is improved, but the vulnerability to tampering during power interruptions worsens
Solution Approach 1:
The patent introduces a checkpoint memory block as an intermediary component that stores reference time values in non-volatile memory. This intermediary preserves critical time information even when power is interrupted, allowing the system to detect and prevent tampering attempts after power restoration.
Solution Approach 2:
The system uses disposable one-time programmable (OTP) memory or fuse-based storage for checkpoint data. These non-volatile, single-write memory locations provide permanent, tamper-resistant storage of checkpoint values that cannot be modified once written, ensuring security even during power interruptions.
3Reliability
If the system implements checkpoint validation logic, then the security against rollback attacks is improved, but the device complexity increases
Solution Approach 1:
The patent divides the RTC system into distinct functional blocks: an RTC block for timekeeping, a checkpoint memory block for storing reference values, and a set RTC logic block for validation. This segmentation allows each component to perform its specific function efficiently while maintaining overall system security through modular design.
Data Source
AI summary
A Real-Time Clock (RTC) block configured to output a current time as part of an ASIC configuration that guarantees that the RTC can never be rolled back beyond a checkpointed date and time. A checkpoint memory block is coupled to the RTC block and configured to include a stored active date/time checkpoint, and a set RTC logic block is coupled to the checkpoint memory block and to the RTC block and configured to permit setting the RTC block to an asserted new time request only when the asserted new time is in the future relative to the stored active date/time checkpoint. The active date/time checkpoint is stored in a non-volatile, single-write memory location such as in a one-time programmable (OTP) memory or in a bank of fuses so that the stored active date/time checkpoint is maintained whether or not power is interrupted to the checkpoint memory block.