JP2013062616A - Storage device, data storage method, and data controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage device capable of improving a security level while reducing a management load on a user.SOLUTION: A storage device includes a non-volatile storage part for storing data to be transmitted from a host device. A host side encryption processing part encrypts data by using a first encryption key and outputs the data as first data. A media side encryption processing part encrypts the first data by using a second encryption key generated through the use of position information in the storage part to which the data is written and allows the storage part to store the data as second data. When the second data is read and rewritten into the storage part, a third encryption key is generated through the use of information of a position for rewriting. Then, the second data is decrypted into the first data by using the second encryption key, and the first data is encrypted again by using the third encryption key and stored in the storage part.

Description

  Embodiments described herein relate generally to a storage device, a data storage method, and a data controller.

  Conventionally, a storage device called SSD (Solid State Drive) has been provided. The SSD uses a flash memory that is a semiconductor memory. In recent years, SSDs are increasingly used as storage devices built in PCs (Personal Computers) instead of HDDs.

  In such an SSD, there is a case where data stored for a long period of time by server backup or the like is encrypted. Even in such a case, since the encrypted data is arranged at the same physical position with the same value, when the device is removed and the nonvolatile area of the device is intentionally analyzed, The physical location of the data was identified and could be attacked intensively. For this reason, periodic encryption key change (re-encryption) processing is recommended.

JP 2006-173853 A

  However, in the SSD using the conventional technique, it is necessary for the user to set the encryption key when performing the re-encryption process. For this reason, the apparatus side cannot perform re-encryption processing at an arbitrary timing. In addition, there is a problem that the user is restricted until the end of the re-encryption process for managing the setting of the encryption key.

  Also, the re-encryption process may take several hours, and it is necessary to always set the encryption key during that period. In the re-encryption process, the data encrypted with the encryption key is decrypted and returned to plain text and then re-encrypted. Therefore, during the re-encryption process, data in plain text is stored in the device. There was a problem of taking the risk of exposure.

  The present invention has been made in view of the above, and an object of the present invention is to provide a storage device, a data storage method, and a data controller that can improve the security level while reducing the management burden on the user. .

  The storage device according to the embodiment includes a nonvolatile storage unit that stores data transmitted from the host device, a host-side encryption processing unit, and a media-side encryption processing unit. The host-side encryption processing unit reads the first encryption key from the storage unit based on user authentication information input from the outside, encrypts the data using the first encryption key, and encrypts the data. 1 data is output. The media-side encryption processing unit generates a second encryption key using information on a write position in the storage unit in which the data is written, and uses the second encryption key to generate the first data Is further encrypted, and the further encrypted second data is stored in the first position of the storage unit. When the second data is read from the first position and written back to the second position in the storage section, the media side encryption processing section uses the second encryption key. Then, the second data is decoded into the first data. Furthermore, the media side encryption processing unit generates a third encryption key using the information on the second position. Further, the media side encryption processing unit re-encrypts the decrypted first data using the third encryption key, and the re-encrypted third data is stored in the second position of the storage unit. Remember.

FIG. 1 is a block diagram showing the configuration of the SSD device according to the first embodiment. FIG. 2 is a diagram illustrating a processing procedure of the re-encryption process. FIG. 3 is a diagram for explaining compaction. FIG. 4 is a block diagram illustrating a configuration of the SSD device according to the second embodiment. FIG. 5 is a diagram illustrating a hardware configuration of a PC used as an information processing apparatus.

  Hereinafter, a storage device, a data storage method, and a data controller according to embodiments will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment.

(First embodiment)
FIG. 1 is a block diagram showing the configuration of the SSD device according to the first embodiment. The SSD device (storage device) 1A is connected to a host system (information processing device) 2 such as a personal computer (hereinafter referred to as a PC) or a CPU core. The SSD device 1A functions as an external memory of the host system 2.

  The SSD device 1A of the present embodiment encrypts data using a user encryption key acquired using a password that is externally input by the user when logging in. In addition, the data is further encrypted using a block encryption key generated based on the position of the block storing the data. When the data storage position is changed (for example, during compaction), the data is decrypted using the block encryption key used for encryption, and re-encryption processing is performed using the new block encryption key. As a result, the SSD device 1A performs re-encryption processing (re-execution of encryption processing) on the data encrypted with the block encryption key.

  The SSD device 1A includes a host controller 3A, a buffer memory 6, a media controller 7A, and a storage medium 10. The host controller 3A performs data transfer control between the host system 2 and the buffer memory 6. The host controller 3A includes a host I / F 4 and a host-side encryption processing unit 5.

  The host I / F 4 is a communication interface that performs data communication between the SSD device 1 </ b> A and the host system 2. The host-side encryption processing unit 5 encrypts data sent from the host system 2 using the user encryption key 14 and sends it to the buffer memory 6. The host-side encryption processing unit 5 decrypts the data in the buffer memory 6 using the user encryption key 14 and sends the data to the host system 2 via the host I / F 4.

  The buffer memory 6 functions as a data transfer cache and a work area memory between the host system 2 and the storage medium 10. Various management tables (such as a logical-physical conversion table described later) are stored in the work area memory of the buffer memory 6.

  The buffer memory 6 is a volatile semiconductor memory such as a DRAM (Dynamic Random Access Memory). Instead of the DRAM, a nonvolatile random access memory such as FeRAM (Ferroelectric RAM), MRAM (Magnetoresistive RAM), or PRAM (Phase change RAM) may be used.

  The media controller 7 </ b> A performs data transfer control between the buffer memory 6 and the storage medium 10. The media controller 7A includes a media-side encryption processing unit 8 and a write management unit 9.

  The media side encryption processing unit 8 encrypts the data in the buffer memory 6 (data encrypted with the user encryption key 14) using the block encryption key 15 and the block write count information 11, and encrypts the data (double encryption). Data) (data encrypted with the user encryption key 14 and the block encryption key 15) is stored in the storage medium 10. Further, the media side encryption processing unit 8 decrypts the data in the storage medium 10 by using the block encryption key 15 and the block write count information 11.

  The media side encryption processing unit 8 re-encrypts the data in the storage medium 10 at a predetermined timing (during compaction or wear leveling described later), and re-encrypted data (the user encryption key 14 and the block encryption key 15). (Encrypted data) is stored in the storage medium 10. The re-encryption process is a process of decrypting the data stored in the storage medium 10 with the block encryption key 15 and then encrypting it again and storing it in the storage medium 10 (building an encryption key for the data being saved). Replacement). At the time of re-encryption, since the block encryption key 15 is newly generated, the data before re-encryption is different from the data after re-encryption.

  The write management unit 9 manages writing of data to the storage medium 10. A logical address (Logical Block Address: LBA) is assigned to data to be written in response to a request from the host system 2. The write command transmitted from the host system 2 includes data requested to be written and a logical address assigned to the data. In the storage medium 10, the block in which the data requested to be written is written is determined by the write management unit 9 regardless of the logical address assigned to the data. The write management unit 9 reads and writes data in the storage medium 10 based on a logical / physical conversion table described later.

  The storage medium 10 is a storage element (semiconductor storage device) as a nonvolatile semiconductor memory made of a semiconductor chip, and is configured using, for example, a NAND flash memory. The storage medium 10 is readable and writable in units called pages, and a plurality of pages are grouped to constitute a storage area of an erasing unit called a block. The storage medium 10 is composed of a plurality of blocks.

  Here, a writing method to the storage medium 10 will be described. The NAND type memory employs a write-once system. In this additional recording method, data is erased in units of blocks, and writing is performed in units of pages for erased blocks. That is, in the NAND type semiconductor memory, it is possible to write to a page that has not been written in the erased block, and it is impossible to overwrite a page that has already been written.

  For this reason, when the logical address designated in the data write request is designated again and a new data write is requested from the host system 2, the SSD device 1A is still written in the erased block. Write new data to a page that does not exist. At this time, the page written last time corresponding to the logical address is invalidated, and the page written with new data is validated.

  In the above-described write-once system, if the number of invalidated pages increases by continuing to write, the capacity that can be written in the storage medium 10 decreases. Then, the number of new erased blocks that can be written, that is, blocks that have not yet been written after erasure (referred to as free blocks) is reduced, and writing becomes impossible when free blocks cannot be secured. End up. In order to prevent this, the media controller 7A performs garbage collection at an appropriate timing. Garbage collection performed in a NAND type semiconductor memory is called compaction.

  Compaction reuses the data area invalidated by additional writing, so after collecting valid data and rearranging it in a free area (free block), it erases the area (block) where there is no valid data and frees it. (Free block). In other words, compaction is a process of reading valid data and rewriting it into a new block.

  In addition, the SSD device 1A performs wear leveling that equalizes (smooths) the number of rewrites for each storage area (region) of the storage medium 10. In the SSD device 1A, a process called compaction or wear leveling is executed on write data as a background process in the device.

  The storage medium 10 stores block write count information 11, user data 12, write position management information 13, user encryption key 14, and block encryption key 15.

  The block write count information 11 is information indicating the data write count for each block. User data 12 is data written from the host system 2.

  The write position management information 13 is, for example, a logical / physical conversion table (address conversion table). The logical-physical conversion table indicates the correspondence between the logical address (LBA) specified by the host system 2 and the physical address specifying the data storage location in the storage medium 10. The logical-physical conversion table is developed in the buffer memory 6 at a predetermined timing such as when a memory system configured using the SSD device 1A and the host system 2 is started. The media controller 7A updates the logical-physical conversion table developed in the buffer memory 6 when the correspondence relationship between the logical address and the physical address is updated with data writing, data erasing, or the like.

  The user encryption key 14 is an encryption key used for encrypting data sent from the host system 2. The user encryption key 14 is read from the storage medium 10 to the host-side encryption processing unit 5 based on user authentication information such as a password.

  The block encryption key 15 is an encryption key used when the data encrypted with the user encryption key 14 is further encrypted or re-encrypted. The block encryption key 15 is generated using the position (block position) in the storage medium 10 where the user data 12 is written.

  In the SSD device 1A, control firmware in the media controller controls re-encryption by the media side encryption processing unit 8 simultaneously with compaction and the like. The control firmware in the media controller controls data encryption by the media side encryption processing unit 8 using the block write count information 11.

  Data sent from the host system 2 is sent to the host-side cryptographic processor 5 via the host I / F 4. At this time, user authentication information such as a password is input from the host system 2 to the host controller 3A. Based on this user authentication information, the host controller 3 A reads the user encryption key 14 from the storage medium 10 and sets the user encryption key 14 in the host-side encryption processing unit 5.

  When the user encryption key 14 is set in the host-side encryption processing unit 5 (when the user logs on), the user data 12 in the storage medium 10 can be read and written correctly. The host-side encryption processing unit 5 encrypts data sent from the host system 2 using the user encryption key 14. Then, the host-side encryption processing unit 5 stores the encrypted data (hereinafter referred to as host-side encrypted data) in the buffer memory 6.

  The media side encryption processing unit 8 further encrypts the host side encrypted data in the buffer memory 6 by using the block encryption key 15 and the block write count information 11 (hereinafter referred to as media side encrypted data). Is stored in the storage medium 10.

  Thereafter, compaction and wear leveling are performed as necessary. Compaction and wear leveling are performed, for example, in a state where the user encryption key 14 is not set in the host-side encryption processing unit 5 (when the user logs off). In the present embodiment, when performing compaction or wear leveling, the media side encryption processing unit 8 re-encrypts the media side encrypted data.

  FIG. 2 is a diagram illustrating a processing procedure of the re-encryption process. Data re-encryption processing by the SSD device 1A is performed, for example, when performing compaction or wear leveling. Here, the re-encryption process when the SSD device 1A performs compaction will be described. Here, a case where the user data 12 is data to be compacted will be described.

  User data 12 as media-side encrypted data is stored in the storage medium 10. When compaction is started (step S5), data to be compacted among the user data 12 (data to be moved to a new block) is read from the storage medium 10 to the buffer memory 6. Specifically, data to be compacted is sent to the media side encryption processing unit 8 via the write management unit 9. As a result, the media side encryption processing unit 8 decrypts the data to be compacted using the block encryption key 15 and the block write count information 11 (step S10), and sends the decrypted data to the buffer memory 6. The data developed in the buffer memory 6 is host side encrypted data (data encrypted with the user encryption key 14).

  The write management unit 9 adds 1 to the number of times of writing a free block in which data to be compacted is newly written, and thereby updates the block write number information 11 (step S20).

  Then, the effective blocks are aggregated on the buffer memory 6 to create write data to the free block. Thereby, compaction is executed on the buffer memory 6 (step S30).

  Here, the compaction processing procedure will be described. FIG. 3 is a diagram for explaining the compaction processing procedure. FIG. 3 shows a transition block diagram of writing and compaction in the SSD device 1A.

  Here, the compaction when the blocks b1 to b4 exist and each of the blocks b1 to b4 has pages 1 to 3 will be described. FIG. 3A shows an initial write state. In the initial writing state, for example, data A1 to C1 are written to pages 1 to 3 of block b1, data D1 to F1 are written to pages 1 to 3 of block b2, and blocks b3 and b4 are free blocks.

  When update writing is instructed from the host system 2 to the data C1, data D1, and data F1, the old data in the block b1 is not physically overwritten, but a free block as shown in FIG. In the block b3, new data is written by additional writing in page units.

  Specifically, the data F1 written in page 3 of block b2 is re-encrypted and written as data F2 in page 1 of block b3. Next, the data D1 written to page 1 of block b2 is re-encrypted and written as data D2 to page 2 of block b3. Further, the data C1 written on page 3 of block b1 is re-encrypted and written as data C2 on page 3 of block b3.

  Then, the data in the old writing part of the block b1 is invalidated. Here, the data F1 written on page 3 of block b2, data D1 written on page 1 of block b2, and data C1 written on page 3 of block b1 are invalidated.

  As the invalid data increases as in the blocks b1 and b2 in FIG. 3B, the use efficiency of the blocks decreases. For this reason, the valid data in the block with a large amount of invalid data is periodically moved / aggregated to the free block. Then, the data stored in the source block is erased and changed to a free block (compaction).

  Specifically, the valid data is read out to the buffer memory 6 via the write management unit 9. Here, as shown in FIG. 3C, data A1 written in page 1 of block b1, data B1 written in page 2 of block b1, and page 2 of block b2 are written. The data E1 is read out to the buffer memory 6. Then, the data B1, E1, and A2 are re-encrypted and written as data B2, data E2, and data A2 on pages 1 to 3 of the block b4.

  At this time, the data in the blocks b1 and b2 is erased and changed to a free block simultaneously with the data writing from the write management unit 9 to the block b4. Thereby, optimization (compaction) of the use area is executed.

  Note that compaction is periodically executed even for blocks with less invalid data in order to smooth the writing frequency of the blocks. Furthermore, in order to smooth the writing frequency of the blocks, the used blocks and free blocks are periodically exchanged as wear leveling.

  In the SSD device 1A, when compaction is executed on the buffer memory 6 and data to be written to the free block is created, the media side encryption processing unit 8 reads the physical position where the host side encrypted data is written (the physical position of the free block). ), A random number, and the block write count information 11, a block encryption key 15 is generated for each physical block unit. The media side encryption processing unit 8 re-encrypts the data to be written to the free block using the updated block encryption key 15 (step S40). The block encryption key 15 generated by the media side encryption processing unit 8 is stored in the storage medium 10.

  A write block cannot be written again unless it is erased once data is written. Therefore, in this embodiment, the block write count information 11 is used for data encryption. For example, the block write count information 11 is used as SEED when generating the block encryption key 15. Thereby, the number of times of writing to the block affects the generated block encryption key 15. For this reason, even if the same data is written again in the same block, the block encryption key 15 is different, so that the media side encrypted data does not have the same data pattern as the previous media side encrypted data.

  The block encryption key 15 may be generated using the physical position where the host side encrypted data is written and the random number without using the block write count information 11. Even in this case, the encryption key depends on the physical position where the host side encrypted data is written. For this reason, when the host-side encrypted data is written into different blocks, the data pattern differs only by changing the writing position, and the encryption key 15 need not be reproduced.

  The re-encrypted data (encrypted data) is written back to the storage medium 10 by the write management unit 9 as host-side encrypted data (step S50). Since actual writing is performed in units of pages, the page key is derived from the block encryption key or generated from the offset within the block.

  The write management unit 9 determines whether or not compaction is performed by re-encrypting all the data to be compacted (step S60). When compaction has not ended (when data that has not been compacted remains) (step S60, No), the processes of steps S10 to S60 are repeated. On the other hand, when compaction is completed (step S60, Yes), the write management unit 9 erases the block invalidated by the process of step S30 to make a free block. Note that the erasure of the block invalidated by the process of step S30 may be a free block at the time of invalidation.

  By re-encrypting the host-side encrypted data, the host-side encrypted data is stored at a new physical location in the storage medium 10. For this reason, the write management unit 9 updates the write position management information 13. At this time, the write position management information 13 is re-encrypted using the block encryption key 15 and the block write count information 11 in the media side encryption processing unit 8 as with the user data 12 (step S70). Then, the write management unit 9 writes the re-encrypted write position management information 13 in the storage medium 10 (step S80).

  As described above, in this embodiment, the media side encryption processing unit 8 is provided separately from the host side encryption processing unit 5. Then, the media side encryption processing unit 8 uses the physical block unit key and the block write count information 11 to encrypt the data.

  As a result, a user encryption key is not required for re-encryption, and therefore re-encryption can be performed in a state where the user encryption key 14 is not set in the host-side encryption processing unit 5. In addition, since re-encryption is performed on the media-side encrypted data, plaintext is never expanded. Therefore, it is possible to perform the re-encryption process while maintaining the encrypted state in units of LBA without exposing the plaintext data. Further, since re-encryption is performed only with information in the SSD device 1A, it becomes possible to perform re-encryption simultaneously with compaction.

  Moreover, since the write position management information 13 is re-encrypted using the block encryption key 15 and the block write count information 11, the analysis of the write position management information 13 can be prevented. Therefore, it is possible to prevent the physical position of the data stored in the storage medium 10 from being specified.

  The compaction target data is not limited to the user data 12, but may be any data (for example, the block write count information 11, the write position management information 13, the user encryption key 14, and the block encryption key 15). Further, in the present embodiment, the case where re-encryption is performed at the time of compaction and wear leveling has been described, but re-encryption may be performed when the encryption key is periodically changed.

  In this embodiment, the re-encryption by the SSD device 1A is taken as an example. However, even in other storage devices, the data write physical position is intentionally changed to be similar to the SSD device 1A. It is possible to obtain the effect.

  As described above, according to the first embodiment, the user encryption key 14 and the block encryption key 15 are used to encrypt data, and the block encryption key 15 is used to re-encrypt the data. It is possible to improve the security level while reducing the burden.

  In addition, since compaction, wear leveling and re-encryption can be compatible, important data stored for a long time by device analysis is not exposed to danger, and the security level can be improved.

  Further, since important information such as the write position management information 13 can be encrypted, it is possible to improve the security level against data destruction and analysis by specifying the physical position.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the host-side cryptographic processing unit 5 and the media-side cryptographic processing unit 8 in the first embodiment are configured as one component.

  FIG. 4 is a block diagram illustrating a configuration of the SSD device according to the second embodiment. Among the constituent elements in FIG. 4, constituent elements that achieve the same functions as those of the SSD device 1 </ b> A of the first embodiment shown in FIG. 1 are assigned the same numbers, and redundant descriptions are omitted.

  The SSD device 1B is a device having the same function as the SSD device 1A, and includes a host controller 3B, a buffer memory 6, a media controller 7B, a storage medium 10, and an encryption processing unit 20. .

  The host controller 3B is connected to the host system 2 and the encryption processing unit 20. The encryption processing unit 20 is connected to the host controller 3B, the buffer memory 6, the media controller 7B, and the storage medium 10. The buffer memory 6 is connected to the encryption processing unit 20 and the media controller 7B. The storage medium 10 is connected to the encryption processing unit 20 and the media controller 7B.

  The host controller 3B includes a host I / F 4, and the media controller 7B includes a write management unit 9. The cryptographic processing unit 20 has a function that combines the functions of the host-side cryptographic processing unit 5 and the media-side cryptographic processing unit 8.

  Data sent from the host system 2 is sent to the cryptographic processing unit 20 via the host I / F 4. At this time, user authentication information such as a password is input from the host system 2 to the host controller 3B. Accordingly, the host controller 3B reads the user encryption key 14 from the storage medium 10 and sets the read user encryption key 14 in the encryption processing unit 20.

  When the user encryption key 14 is set in the encryption processing unit 20 (when the user logs on), the user data 12 in the storage medium 10 can be correctly read and written. For example, the encryption processing unit 20 encrypts data sent from the host system 2 using the user encryption key 14. Then, the encryption processing unit 20 stores the encrypted data in the buffer memory 6 as host side encrypted data.

  The encryption processing unit 20 further encrypts the host-side encrypted data in the buffer memory 6 using the block encryption key 15 and the block write count information 11, and stores the encrypted data in the storage medium 10 as user data 12. .

  Thereafter, compaction and wear leveling are performed as necessary. When it is time to compact the user data 12, data to be compacted among the user data 12 is read from the storage medium 10 to the buffer memory 6. As a result, the encryption processing unit 20 decrypts the data to be compacted using the block encryption key 15 and the block write count information 11 and sends the decrypted data to the buffer memory 6. The data developed in the buffer memory 6 is host side encrypted data (data encrypted with the user encryption key 14). Then, the cryptographic processing unit 20 uses the physical position (physical position of the free block) where the host side encrypted data is written, the random number, and the block write count information 11 to use the block encryption key 15 for each physical block unit. Create The encryption processing unit 20 re-encrypts the data to be written to the free block using the updated block encryption key 15.

  Then, the re-encrypted data is written back to the storage medium 10 by the write management unit 9 as host-side encrypted data. When the compaction is completed, the write management unit 9 erases the block invalidated by the compaction to make a free block.

  The SSD devices 1A and 1B are used as storage means of the information processing device. FIG. 5 is a diagram illustrating a hardware configuration of a PC used as an information processing apparatus. Here, the information processing apparatus 500 including the SSD apparatus 1B will be described.

  As illustrated in FIG. 5, the information processing apparatus 500 includes a CPU 501, a RAM 502, a ROM 503, a power supply unit 504, an input interface (I / F) 505, and an SSD device 1B.

  In the information processing apparatus 500 according to the present embodiment, when power is turned on by the power supply unit 504, a BIOS (Basic Input / Output System) stored in the ROM 503 is read by the CPU 501 and operates using the RAM 502 as a work area. To do.

  As described above, according to the first and second embodiments, it is possible to improve the security level while reducing the management burden on the user.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1A, 1B ... SSD apparatus, 2 ... Host system, 3A, 3B ... Host controller, 5 ... Host side encryption processing part, 7A, 7B ... Media controller, 8 ... Media side encryption processing part, 10 ... Storage media, 11 ... Block Write count information, 12 ... user data, 13 ... write position management information, 14 ... user encryption key, 15 ... block encryption key, 20 ... encryption processing unit, 500 ... information processing device, b1-b4 ... block

Claims (8)

A non-volatile storage unit for storing data sent from the host device;
The host side that reads out the first encryption key from the storage unit based on user authentication information input from the outside, encrypts the data using the first encryption key, and outputs the encrypted first data An encryption processor;
A second encryption key is generated using information on a writing position in the storage unit in which the data is written, and the first data is further encrypted using the second encryption key, and the further encryption is performed. A media-side encryption processing unit for storing second data in a first position of the storage unit;
With
When reading the second data from the storage unit from the first location and writing it back to the second location in the storage unit, the media side encryption processing unit uses the second encryption key to The second data is decrypted into the first data, a third encryption key is generated using the information on the second position, and the decrypted first data is used as the third encryption key. A storage device that re-encrypts the data and stores the re-encrypted third data in the second position of the storage unit.   The storage device according to claim 1, wherein the media-side encryption processing unit generates the second encryption key by further using a data rewrite count for each data erasing unit including the second position in the storage unit.   During compaction, which is a process of reading valid data from the storage unit and rewriting it into a new block, the media side encryption processing unit performs the re-encryption and stores the re-encrypted third data in the storage unit The storage device according to claim 1, wherein the storage device is stored in the second position.   At the time of wear leveling for leveling the number of data rewrites in the storage unit, the media-side encryption processing unit performs the re-encryption, and the re-encrypted third data is stored in the second position of the storage unit. The storage device according to claim 1, wherein the storage device is stored in the storage device. The storage unit further stores write position information indicating a correspondence relationship between a logical address specified by the host device and a physical address specifying a position where the data is written in the storage unit;
The media-side encryption processing unit encrypts the writing position information using the second encryption key, and stores the encrypted writing position information in the storage unit. The storage device described.   The storage device according to claim 1, wherein the storage unit is configured using a NAND flash memory. A first encryption key is read out based on user authentication information inputted from the outside in a non-volatile storage unit that stores data sent from the host device, and the data is encrypted using the first encryption key. And a first encryption step for outputting encrypted first data;
A second encryption key is generated using information on a writing position in the storage unit in which the data is written, and the first data is further encrypted using the second encryption key, and the further encryption is performed. A second encryption step for storing second data in a first position of the storage unit;
Including
When reading the second data from the storage unit from the first position and writing it back to the second position in the storage unit, the second data is written to the second data using the second encryption key. Decrypting the first data, generating a third encryption key using the second position information, re-encrypting the decrypted first data using the third encryption key, and A data storage method for storing re-encrypted third data in a second position of the storage unit. A first encryption key is read from the storage unit based on user authentication information inputted from the outside in a non-volatile storage unit that stores data sent from the host device, and the first encryption key is used. A host-side encryption processing unit that encrypts the data and outputs the encrypted first data;
A second encryption key is generated using information on a writing position in the storage unit in which the data is written, and the first data is further encrypted using the second encryption key, and the further encryption is performed. A media-side encryption processing unit for storing second data in a first position of the storage unit;
With
When reading the second data from the storage unit from the first location and writing it back to the second location in the storage unit, the media side encryption processing unit uses the second encryption key to The second data is decrypted into the first data, a third encryption key is generated using the information on the second position, and the decrypted first data is used as the third encryption key. A data controller that re-encrypts the data and stores the re-encrypted third data in the second position of the storage unit.

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