OTP Unidirectional Counter for Software Rollback Prevention
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Solution Overview
Problem
Existing systems lack a mechanism to ensure that software versions can only be updated in one direction, preventing rollback to insecure or obsolete versions, which is crucial for maintaining security and functionality.
Innovation Solution
Implementing unidirectional counters using one-time-programmable memory, such as flash or EEPROM, to store a minimum software version that can only be incremented, ensuring that only newer, secure versions can be installed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional memory devices are used to store software version information, then the version can be updated freely in both directions, but the system cannot prevent rollback to insecure or obsolete versions
Solution Approach 1:
The memory device is segmented into multiple memory locations, where at least one location stores the version counter and another location stores a counter of ones. This segmentation allows the system to maintain separate control over the version number and its increment state, enabling unidirectional updates while preserving the ability to store comprehensive version history for security purposes.
Solution Approach 2:
The system performs preliminary action by setting a counter of ones to a non-zero value before allowing a version update. This preliminary state change prevents subsequent decreases to the version counter, thereby preventing rollback to insecure or obsolete versions while maintaining update flexibility in the allowed direction.
2Reliability
If a unidirectional counter is implemented using one-time-programmable memory, then the version can only be incremented, but the device complexity increases
Solution Approach 1:
The memory device is designed to serve multiple functions: it stores the version counter, maintains a counter of ones to enforce unidirectionality, and provides tamper detection capabilities. By making the memory structure multi-functional, the patent reduces overall system complexity compared to using separate dedicated components for each function.
Solution Approach 2:
The counter of ones acts as an intermediary mechanism between the version counter and the update control logic. Instead of directly preventing version decreases through complex control circuits, the system uses the counter of ones as a mediator that simplifies the enforcement of unidirectional updates through straightforward comparison logic.
3Ease of operation
If the version counter is stored in readable memory that can be modified, then the system remains flexible for updates, but tampering with the version information becomes possible
Solution Approach 1:
The system incorporates feedback mechanisms through tamper detection logic that monitors changes to the version counter and the counter of ones. When unauthorized modifications are detected, the system can respond by blocking updates or alerting the user, thereby maintaining ease of legitimate updates while preventing tampering through continuous monitoring and response.
Data Source
AI summary
Apparatuses, systems, and techniques that implement a unidirectional counter with one-time-programmable memory that prevents the counter from reversing direction. In at least one embodiment, a unidirectional counter is implemented with a base value represented as a binary number and an offset represented as a bit field where each bit represents an equal amount.