Method for realizing safety and integrity of files in smart card
A smart card and file technology, applied in the field of intelligence, can solve problems such as abnormal file storage space status and abnormal file access.
Active Publication Date: 2011-05-25
东方口岸科技有限公司
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Problems solved by technology
[0011] 2. Release the space occupied by the file
[0012] It can be seen from the above simplified process that if the user pulls out the card between the process 1 and 2 of creating a file, or pulls out the card between process 1 and 2 of deleting a file, the state of the file storage space will be changed. Abnormal, which may lead to abnormal file access
Method used
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[0017] The basic idea of this method is: backup the original file allocation table FAT with a backup FAT; set a storage area in the smart card to store the state of the file system and the cyclic redundancy check code CRC of the above two FAT; file creation or deletion starts When the original FAT is changed, the modified original FAT is copied to the backup FAT when the file is created or deleted, so that the original FAT and the backup FAT are consistent; when the smart card is reset, the CRC check is performed on the original FAT and the backup FAT, and Combining the status of the file system to restore or backup, the CRC check result includes normal and abnormal, the status of the file system includes normal status, modified status and unbacked status, recovery refers to copying the backup FAT to the original FAT, the backup is Refers to copying the original FAT to the backup FAT.
[0018] Preferably, as figure 1 As shown, the method includes the following steps when th...
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The invention discloses a method for realizing safety and integrity of files in a smart card, which comprises the following steps: backing up a backup FAT (file allocation table) for the original FAT; setting a storage region in the smart card for storing the state of a file system and cyclic redundancy check (CRC) codes of the two FATs; modifying the original FAT when beginning to create or delete the file, and copying the original FAT after modification to the backup FAT when the creation or the deletion of the file is finished so as to enable the original FAT to be consistent with the backup FAT conveniently; and performing CRC checking on the original FAT and the backup FAT under the situation that the smart card is reset, and performing recovery or backup operation in combination with the state of the file system, wherein the CRC checking results comprise normal and abnormal; the states of the file system comprise the normal state, the modified state and non-backup state; the recovery refers to the operation of copying the backup FAT to the original FAT; and the backup refers to the operation of copying the original FAT to the backup FAT.
Description
technical field [0001] The invention belongs to the field of smart technology, and in particular relates to a method for ensuring the security and integrity of files in a smart card. Background technique [0002] Since the smart card is in the process of creating and deleting files, the user's plugging and unplugging may cause data inconsistency in the card, resulting in damage to the file system and affecting the use of the smart card. Therefore, the security of the file system in the smart card is the focus of the smart card operating system. How to ensure the security and integrity of the files in the smart card is a difficult point in the design of the smart card operating system. [0003] FAT (File Allocation Table, file allocation table) 16 is a kind of file system format that adopts in DOS and Windows operating system, and its core is to adopt file allocation table (FAT) to maintain all files in the system. However, in a general system, when there is a problem with t...
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Inventor 戚涛颜静戚天龙
Owner 东方口岸科技有限公司