Non-Volatile Memory Write Integrity via Buffer Sector Backup
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Solution Overview
Problem
Power cuts during data writing in non-volatile memory of security devices, such as integrated circuit cards, lead to data loss, corruption, or inability to boot the operating system, and existing backup solutions are not reliable.
Innovation Solution
A method involving backing up updated data and its address in a buffer sector and a flag slot before updating the target memory sector, with completion indicators ensuring data integrity and allowing recovery from power cuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is written directly to the target memory sector without backup, then the writing operation is simple and fast, but power cuts during writing cause data loss or corruption
Solution Approach 1:
The patent applies preliminary action by backing up the updated data and its address to a buffer sector and flag slot before actually updating the target memory sector. This preparatory backup ensures that if a power cut occurs during the writing operation, the original data remains intact and can be recovered, thus preventing data loss while maintaining a relatively simple writing process structure.
2Reliability
If existing backup solutions are used, then some protection against power cuts is provided, but they are not reliable and can lead to memory corruptions
Solution Approach 1:
The patent introduces an intermediary mechanism using a dedicated buffer sector and flag slot system. The buffer sector stores backup copies of updated data, while the flag slot contains the address of the target memory sector and a completion indicator. This intermediary backup structure provides reliable protection because it separates the backup function from the target storage, allowing verification of backup completion through the flag slot before considering the writing operation complete, thus preventing memory corruption even if power cuts occur during the process.
3Reliability
If backup operations are performed before updating target sector, then data protection is improved, but the writing process time increases
Solution Approach 1:
The backup operation is performed as a preliminary action before the actual target sector update, but the patent optimizes this by using a dedicated buffer sector that can be prepared in advance. The flag slot mechanism allows the system to quickly verify whether backup is complete without requiring time-consuming checks, thus minimizing the time overhead while ensuring data protection.
4Measurement precision
If no monitoring mechanism is used, then the writing process is simpler, but it is impossible to detect whether data has been fully written or if tearing occurred
Solution Approach 1:
The patent implements a feedback mechanism through the flag slot, which contains a completion indicator that provides information about the writing status. When data is backed up to the buffer sector, the system can check the flag slot to determine whether the backup is complete or if a power cut interrupted the process. This feedback enables precise detection of writing completion without requiring complex monitoring structures, as the flag slot provides a simple binary state indication.
Data Source
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AI summary
The present invention relates to method for writing data into a non-volatile memory (NVM) of an integrated circuit of a security device and, also, to a security device, a computer program, and a recording medium (NVM). The proposed method comprises: - a writing process executed to update a target memory sector (Sx) of the non-volatile memory (NVM) and comprising: ∘ writing updated memory sector data of the target memory sector (Sx) into a current buffer sector (BSn) of the non-volatile memory (NVM); and ∘ writing the address of the target memory sector (Sx) into a current flag slot (FSn) of of the non-volatile memory (NVM) associated with the current buffer sector (BSn).