Card Computing Device Transactional Memory Integrity
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Solution Overview
Problem
Card computing devices face security risks and data integrity issues due to potential tampering when experiencing card tear events, as they may lose access to a power source during incomplete transactions, and existing verification methods are inadequate to ensure the integrity of transaction data.
Innovation Solution
A method involving copying transaction rollback data to a buffer in a first memory, calculating and storing a checksum, and writing this data to a second memory, along with a checksum pointer, to restore the heap to a previous state in case of a card tear event, ensuring data integrity and preventing tampering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If checksum verification is implemented to protect transaction data integrity, then security against tampering is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by calculating and storing the checksum of transaction rollback data before the actual transaction execution. This pre-calculated checksum is stored in a dedicated register along with a pointer to the valid data region. When a card tear event occurs, the system can immediately verify data integrity using this pre-computed checksum without needing to recalculate it, thus providing security while minimizing the complexity of real-time verification operations.
2Reliability
If transaction rollback data is stored in memory to enable recovery after card tear events, then reliability is improved, but vulnerability to tampering increases
Solution Approach 1:
The patent introduces an intermediary mechanism - a checksum value that acts as a mediator between the transaction rollback data and the verification process. The checksum is calculated over the rollback data and stored separately in a register. This intermediary allows the system to verify whether the rollback data has been tampered with by comparing the stored checksum against a newly calculated checksum, thereby protecting the recovery capability from malicious modifications without requiring the rollback data itself to be encrypted or physically protected.
3Stability of the object's composition
If the card computing device attempts to revert operations after power reconnection, then consistency is improved, but risk of executing unintended operations increases
Solution Approach 1:
The patent implements feedback by verifying the integrity of transaction rollback data through checksum comparison before allowing the system to execute recovery operations. After a card tear event and power reconnection, the system calculates a new checksum from the stored rollback data and compares it with the pre-stored checksum value. Only if the checksums match (indicating no tampering occurred) does the system proceed with the revert operations. This feedback mechanism ensures system consistency while preventing unintended operations that could result from executing corrupted or maliciously modified rollback data.
Data Source
AI summary
A method may include copying transaction rollback data to a buffer in a first memory. The method may further include calculating a checksum for the transaction rollback data, and storing the calculated checksum and a checksum pointer in the first memory. The checksum pointer may refer to a last valid location in a transactional memory region of the second memory for which the checksum is calculated. The method may further include writing, to the transactional memory region, the transaction rollback data from the buffer and the checksum and the checksum pointer from the first memory, and performing at least part of the transaction by writing new transaction data to the heap. The transaction rollback data may be useable to restore the heap to a state prior to initiating the transaction if the transaction was incomplete, upon reconnecting the card computing device after determining that a card tear event has occurred.