Abstract:
A method and apparatus for preventing a user from interpreting optional stored data information even when the user extracts the optional stored data, by managing data associated with a flash memory in a flash translation layer, the method comprising searching at least one page of the flash memory when writing data to the flash memory, determining whether authority information corresponding to respective searched pages includes an encryption storage function, generating, corresponding to respective searched pages, a page key according to an encrypting function when the authority information includes the encryption storage function encrypting the data using the generated page key and storing the encrypted data in the respective searched pages, and storing the data in the respective searched pages without encryption when the authority information does not include the encryption storage function.

Description:
PRIORITY 
     This application is a Continuation Application of U.S. application Ser. No. 12/017,723 filed in the U.S. Patent and Trademark Office on Jan. 22, 2008 and claims priority under 35 U.S.C. §119(a) to an application filed in the Korean Intellectual Property Office on Jan. 22, 2007 and assigned Serial No. 10-2007-00006593, the content of each of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a flash translation layer, and more particularly to a flash memory for processing optional data and a method thereof. 
     2. Description of the Related Art 
     Generally, flash memories are storage devices, which maintain their data even during power-off. Specifically, the flash memories have low power consumption and therefore, retain their stored data, even when their power supplies are interrupted. That is, unlike Dynamic Random Access Memories (DRAMs) the flash memories are non-volatile memory devices and because the flash memories retain their stored data even when their power supplies are interrupted, they are widely used in electronic devices such as digital televisions, digital camcorders, hand-held sets (e.g., cellular phones), digital cameras, Personal Digital Assistants (PDAs), game machines, MP3 players and the like. 
     However, when optional data are stored in a conventional flash memory, since original data are stored without any processing, a user can extract the data from the flash memory and simply recognize the meanings of the extracted data. In particular, when a code and a debug symbol table are stored in the flash memory, the user can perform reverse engineering by reading the data stored in the flash memory. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an aspect of the present invention is to provide a method for encrypting the optional stored data, such that even when the user extracts the optional stored data, the data is not easily interpreted. 
     According to an aspect of the present invention, there is provided a method for managing data associated with a flash memory in a flash translation layer, the method comprising searching at least one page of the flash memory when writing data to the flash memory, determining whether authority information corresponding to respective searched pages includes an encryption storage function, generating, corresponding to respective searched pages, a page key according to an encrypting function when the authority information includes the encryption storage function encrypting the data using the generated page key and storing the encrypted data in the respective searched pages, and storing the data in the respective searched pages without encryption when the authority information does not include the encryption storage function. 
     According to another aspect of the present invention, there is provided an apparatus for managing data associated with a flash memory, comprising a flash memory, a controller, and a flash translation layer for searching at least one page of the flash memory for storing the data when a write of optional data is requested from the controller, determining whether authority information corresponding to respective searched pages includes an encryption storage function, generating, corresponding to respective searched pages, a page key according to an encrypting function when the authority information includes the encryption storage function, encrypting the data using the page key, storing the encrypted data in the respective searched pages, and storing the data in the respective searched pages without encryption when the authority information does not include the encryption storage function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram of a terminal according to the present invention; 
         FIG. 2A  shows data format of a flash memory unit according to the present invention; 
         FIG. 2B  is a data block of the flash memory according to the present invention; 
         FIG. 2C  shows a spare array included in a page of a flash memory according to the present invention; 
         FIG. 3  is a flow chart of an operation where the terminal writes optimal data in the flash memory; and 
         FIG. 4  is a flow chart of an operation where the terminal reads optimal data from the flash memory. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same elements will be designated by the same reference numerals although they are shown in different drawings. Further, various specific definitions found in the following description, such as specific values of packet identifications, contents of displayed information, etc., are provided only to help general understanding of the present invention, and it should be apparent to those skilled in the art that the present invention can be implemented without such definitions. Further, in the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. 
     Structural elements of the terminal will be described with reference to  FIG. 1 . 
     The terminal includes a controller  101 , a flash translation layer (FTL)  105 , and a flash memory  107 . FTL  105  is connected to controller  101 . Flash memory  107  is connected to FTL  105 . 
     The Flash memory  107  can store optional data or load optional written data under the control of controller  101 . In particular, flash memory  107  may receive and store encrypted data under the control of controller  101  or load optional encrypted and stored data. 
     Referring to  FIG. 2A , flash memory  107  includes data blocks  201  and a Partition Information Table (PIT)  203 . Data blocks  201  include a plurality of blocks, and are an area for storing optional data when a write is requested from a user. Data blocks  201  may be divided into a plurality of partitions. Data blocks  201  may be authorized to have different functions according to partition regions. For example, when data blocks  201  is divided into two partitions, it is authorized to enable one partition region to have a read function, a write function, and an encryption storage function for storing optional encrypted data, and another partition region to have only the read function and the write function. 
     PIT  203  includes information about flash memory  107 . In detail, PIT  203  includes physical address information and the partition number information of data blocks  201 , Logical Block Number (LBN) information and authority information of each partition. 
     Authority information of each partition indicates authority that a corresponding partition region has. For example, when an optional partition region supports a read function R, a write function, and an encryption storage function C, authority information can be generated to include the fact that a corresponding partition region provides the aforementioned functions. Further, a terminal analyzes authority information of PIT  203  to confirm functions, which an optional partition region provides. 
     Moreover, in a detailed construction of data blocks  201  as shown in  FIG. 2B , an optional block  211  includes a plurality of pages  209 . Each of pages  209  is divided into a main array  205  and a spare array  207 . Main array  205  is an area for practically storing predetermined data, and spare array  207  is an area for storing Meta information with respect to main array  205 . 
     The Meta information stored in spare array  207  will be explained with reference to  FIG. 2C . The Meta information includes logical block number information  213  and the number information  215  (ECNT 0 -ECNT 3 ) of cancel times. The logical block number information  213  (LBN 0 -LBN 3 ) indicates a logical block number of a block including a current page. Number information  215  of cancel times indicates the number of cancel times of a block including a current page. Spare array  207  includes a Main array Error Checking and Correction (MECC)  217  and a Spare array Error Checking and Correction (SECC)  219 . MECC  217  is used to check and correct an error of a main array included in a current page. SECC  219  is used to check and correct an error of a spare array included in the current page. Spare array  207  includes bad Block Information (BI)  221  and Allocation Information AI  223 . BI  221  functions to indicate whether or not a block included in the current page is bad. The AI functions to indicate a state of the current page. Further, spare array  207  may include a reserved area RSV for storing additional information. 
     Where storage areas of BI  221  and AI  223  have 1 byte, and when BI  221  is 0xFF, it is indicated that the block is normal. In contrast to this, when BI  221  is not 0xFF, it is indicated that the block is abnormal. Further, when the AI  223  is 0xFF, it may indicate that the current page is not used, and also, when the AI  223  is 0xFF, it may indicate that optional data are stored in the current page. When AI  223  is 0x00, it may indicate that storage of the optional data in the current page is terminated. 
     The internal construction of flash memory  107  has been described with reference to  FIG. 2A  to  FIG. 2C .  FIG. 2A  to  FIG. 2C  refer to one embodiment. An area in which information about flash memory  107  is disposed can be changed according to how flash memory  107  is constructed. 
     Returning to  FIG. 1 , flash translation layer  105  provides an interface to a file system and an application program so that flash memory  107  can be used as a block device such as a Hard Disk Drive (HDD) or a Random Access Memory (RAM). In other words, flash translation layer  105  causes controller  101  to recognize flash memory  107  as an HDD or RAM. That is, flash translation layer  105  causes controller  101  to access flash memory  107  in the same manner as that of the HDD or the RAM. Flash translation layer  105  has a logical address-physical address event information management function, a bad block management function, and a data wear leveling function. 
     In particular, flash translation layer  105  according to the present invention includes an encryption/decryption unit  103 . When controller  101  requests a write command from flash translation layer  105 , flash translation layer  105  receives, encrypts, and stores optional data in flash memory  107 . Here, the write command is a command to store the optional data in flash memory  107 . When controller  101  request a read command from flash translation layer  105 , flash translation layer  105  loads, decodes, and outputs optional encrypted data from flash memory  107  to controller  101 . Here, the read command is a command to load the optional data previously stored in flash memory  107 . 
     Encryption/decryption unit  103  of flash translation layer  105  provides an encrypting function to perform an encryption/decryption, and can encrypt or decode optional data using the encrypting function. Encryption/decryption unit  103  cannot encrypt the optional data by a root key, and input a root key and optional data in the encrypting function to generate a processed root key. Further, encryption/decryption unit  103  may encrypt the optional data by the processed root key, and decode optional encrypted data. 
     For example, encryption/decryption unit  103  may provide a one-way hash function as the encrypting function. The one-way hash function indicates an equation in which a reverse operation is impossible. Specifically, the one-way hash function outputs a corresponding value to only one way as optional input value. Here, one way means that anyone can calculate a hash value for one way but cannot analogize an input value with respect to the hash value. 
     In particular, flash translation layer  105  receives a write command from controller  101 ; it searches a page  209  in which optional data are stored among pages included in flash memory  107 . Further, flash translation layer  105  calculates a physical address corresponding to the searched page. Moreover, flash translation layer  105  analyzes spare array  107  included in searched page  209  to search logical block number information  213  and number information  215  of cancel times. Flash translation layer  105  calculates a logical block number corresponding to a current page and the number of cancel times of a block included in the current page. Flash translation layer  105  inputs a root key in the encrypting function together with the calculated physical address, logical block number, and the number of cancel times to generate a processed root key. The processed root key is referred to as the ‘page key’. 
     For example, when a one-way hash function is used as the encrypting function, flash translation layer  105  inputs the calculated physical address, logical block number, the number of cancel times, and root key in the one-way hash function to generate a processed root key hash value. The hash value can be also referred to as the ‘page key’. 
     Flash translation layer  105  encrypts optional data by the page key, and stores the optional encrypted data in searched page  209 . 
     Further, when flash translation layer  105  receives a read command from controller  101 , it searches a page including data for which a read is requested among the pages included in flash memory  107 . Next, flash translation layer  105  calculates a physical address corresponding to searched page  209 . Also, flash translation layer  105  analyzes a spare array  207  included in searched page  209  to search logical number information  213  and number information  215  of cancel times in a current page. Then, flash translation layer  105  calculates a logical block number corresponding to the current page and the number of cancel times of a block including the current page using the searched logical number information  213  and number information  215  of cancel times. Subsequently, flash translation layer  105  inputs the calculated physical address, logical block number, and the number of cancel times in the encrypting function to generate a processed root key. 
     Furthermore, flash translation layer  105  loads optical data included in searched page  201 , and decodes and outputs the optional loaded data by a page key to controller  101 . 
     Controller  101  controls respective structural elements of a terminal so as to provide various functions of the terminal. In particular, controller  101  of the present invention controls flash translation layer  105  to encrypt and store optional data in flash memory  107 . Otherwise, controller  101  controls flash translation layer  105  to load and decode optional data encrypted and stored in flash memory  107 , and to receive, change, and output corresponding data. 
     So far, the structural elements of the terminal according to the present invention have been explained with reference to  FIG. 1  to  FIG. 2C . Hereinafter, the following is a procedure of storing or loading data by the terminal according to the present invention. 
     An operation of encrypting and storing optional data when storing the optional data in flash memory  107  will be now explained with reference to  FIG. 3 . 
     In order to simply explain the present invention, it is assumed that the size of optional data and the size of optional encrypted data are not greater than that of a page region, and there is an authority for performing a write function in a partition including a block having a page for storing the optional data. 
     In step  301 , flash translation layer  105  confirms whether a write command is inputted from controller  101 . Here, the write command is a command to store optional data in flash memory  107 . When the write command is not input, step  301  is repeatedly performed until the write command is input. When the write command is inputted, the routine goes to step  303 . 
     At step  303 , flash translation layer  105  searches a page in which optional data are stored among pages of flash memory  107 . 
     Specifically, flash translation layer  105  receives a Logical Page Number (LPN) from controller  101 , which is a page number in which optional data are stored. Flash translation layer  105  searches a page  209  corresponding to the received logical page number, and receives data included in main array  205  and spare array  207  of searched page  209 . Next, flash translation layer  105  confirms a logical block number by logical block number information included in spare array  207 , and calculates a physical address of a current page in the confirmed logical block number. A method for calculating the physical address by flash translation layer  105  can be changed according to sizes of a block area and a page area in flash memory  107 . 
     In step  305 , a decision is made to determine if the data will be encrypted. For example, flash translation layer  105  analyzes a partition information table  203  to confirm authority information of a partition including a current page. If the optional data should be stored without the encryption, the process goes to step  313 . When it is confirmed that encryption is necessary when storing optional data in a partition according to the authority information, flash translation layer  105  goes to step  307 . 
     When the process goes to step  313 , flash translation layer  105  receives optional data from controller  101 , and stores the optional received data in a main array of a current page  209 . 
     When the process goes to step  307 , flash translation layer  105  generates a page key for encrypting optional data. 
     Specifically, flash translation layer  105  detects the number information of cancel times included in spare array  209 , and calculates the number of cancel times of a block including the current page  209 . Further, flash translation layer  105  inputs the physical address, logical block number, the number of cancel times calculated in step  303 , and a predetermined root key in the encrypting function to generate a page key, and the process goes to step  309 . 
     Next, in step  309 , flash translation layer  105  receives optional data from the controller  101 , and encrypts the optional received data by the page key generated in step  307 , and the process goes to step  311 . 
     Subsequently, in step  311 , flash translation layer  105  stores the optional data encrypted in step  309  in a page  201  of flash memory  107  searched in step  301 . 
     Through the aforementioned operation, when the terminal stores optional data in flash memory  107 , it can encrypt and store the optional data. 
     Referring to  FIG. 4 , a description of an operation of detecting and decoding optional encrypted data when optional data are loaded from the flash memory  107  follows. 
     In order to simply explain the present invention, it is assumed that the size of optional data and the size of optional encrypted data are not greater than that of a page region, and there is an authority for performing a write function in a partition including a block having a page for storing the optional data. 
     In step  401 , flash translation layer  105  confirms whether a read command is inputted from controller  101 . Here, the read command is a command to load optional data stored in a flash memory  107  from controller  101 . When the read command is not input, the flash translation layer  105  repeats step  401  until the read command is input. When the read command is inputted, flash translation layer  105  goes to step  403 . 
     In step  403 , flash translation layer  105  searches a page storing optional data for which a read is currently requested among pages of flash memory  107 . 
     Specifically, flash translation layer  105  receives a Logical Page Number (LPN) from controller  101 . Here, the LPN is a page number in which optional data are stored. Next, flash translation layer  105  searches a page  209  corresponding to the received logical page number, and receives data included in a main array  205  and a spare array  207  of searched page  209 . Further, flash translation layer  105  confirms a logical block number as logical block number information included in spare array  207 , and calculates a physical address of a current page in the confirmed logical block number. A method for calculating the physical address by flash translation layer  105  can be changed according to a size of a block area and of a page area in flash memory  107 . 
     Subsequently, in step  405 , flash translation layer  105  confirms whether the optional data are encrypted. When the optional data are not encrypted, flash translation layer  105  goes to step  413 . When the optional data are encrypted, flash translation layer  105  goes to step  407 . 
     For example, flash translation layer  105  analyzes partition information table  203  to confirm authority information of a partition to which current page  209  belongs. When it is confirmed that the optional data stored in current page  209  are encrypted according to the authority information, flash translation layer  105  goes to step  407 . When the process goes to step  413 , flash translation layer  105  outputs optional data received from main array  205  of a corresponding page  209  to controller  101 . 
     When the process goes to step  407 , flash translation layer  105  generates a page key for decoding the optional data. 
     Specifically, flash translation layer  105  detects the number of cancel times included in spare array  209 , and calculates the number of cancel times of a block including a current page  209  according to the number information of cancel times detected. Next, flash translation layer  105  inputs the physical address, the logical block number, and the number of cancel times calculated in step  403  and a predetermined root key in the encrypting function to generate a page key, and goes to step  409 . 
     Subsequently, in step  409 , the flash translation layer  105  decodes the optional data received from the main array  205  of a corresponding page  209  in step  401  by a page key generated in step  407 , and goes to step  411 . 
     In step  411 , flash translation layer  105  outputs the optional data decoded in step  409  to controller  101 , so that controller  101  can perform a corresponding function. 
     Through the aforementioned operation, the terminal can decode and load the optional data, which are encrypted and stored from flash memory  107 . 
     For example, in the embodiment of the present invention, the flash memory included in the terminal can be attachable/detachable flash memory. 
     As is clear from the foregoing description, the present invention prevents a user from interpreting information in optional data stored in a flash memory even when the user extracts the optional data. 
     While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as further defined by the appended claims.