Method and apparatus for implementing secure and selectively deniable file storage

A system for writing data to a memory device arrangement comprising:

• a first and a second memory devices, wherein the first memory device comprises data blocks numbered with physical block numbers the system comprises means for:
• a. calculating a digest from at least part of a data block content,
• b. recording the digest and the logical block number in a record of a redirection table using the logical block number as index of the record,
• c. selecting a physical block number, into which the data block content in the first memory device is to be stored, from a list of the free physical blocks in the first memory device,
• d. encrypting the data block content,
• e. storing the data block content into the first memory device in the position pointed by the physical block number, and
• f. storing the digest or a number derived from it and the physical block number into the second memory device.

A computer program stored in a non-transitory computer-readable medium, for writing data to a memory device arrangement comprising a first and a second memory device in which the first memory device comprises a plurality of data blocks numbered with physical block numbers and the second memory device comprises references calculated from the data block digests and the physical block numbers, the computer program comprising computer executable instructions for performing the following functions:

• a. calculating a digest from a data block content,
• b. recording the digest and the logical block number in a record of a redirection table using the logical block number as an index of the record,
• c. receiving a physical number of the block, into which data block content is to be stored in the first memory device, the physical block number being selected from a list of the free physical blocks in the first memory device,
• d. encrypting the data block content,
• e. storing the data block content to the first memory device to the position pointed by the physical block number,
• f. storing the digest, or a number derived from it, and the physical block number to the second memory device.