JP5792526B2 - Memory system and information protection method - Google Patents

Description

  The present invention relates to a technique for protecting information stored in a storage device (for example, a semiconductor memory) from being illegally copied.

  Conventionally, a technique for protecting information stored in a storage device connected to a host computer from unauthorized duplication is known. For example, such a technique is described in Patent Document 1.

  In Patent Document 1, a controller having a security function and a nonvolatile memory are provided in a memory system connected to a host computer. For access from a host computer, a technique for protecting information stored in a nonvolatile memory by the controller performing a security function is described.

  However, even with the technique described in Patent Document 1, unauthorized duplication cannot be completely prevented. Then, the security function in the controller of the memory system is broken, and there actually occurs a situation where information stored in the nonvolatile memory (information to be protected) is illegally copied and distributed. In the technique described in Patent Document 1, since the host computer and the memory system cooperate to provide a security function regardless of the program stored in the nonvolatile memory, this security is once broken. If done, it could also allow all programs to be copied illegally.

  As a method for easily solving such a situation, it is conceivable to change the security function provided by the controller.

JP 2008-040941 A

  However, in the technique described in Patent Document 1, when the security function in the controller of the memory system is changed, there is a problem that the host computer side also needs to be changed. In other words, in the current situation where many host computers are already distributed in the market, it is not practical in terms of maintaining compatibility and cost to perform design changes on the host computer side whenever the security function of the memory system is broken. There was no problem.

  The present invention has been made in view of the above problems, and a memory system connected to a host computer is stored in the memory system at a low cost while maintaining compatibility with already-distributed host computers. It is an object to provide a technology for suppressing unauthorized duplication of information.

In order to solve the above-mentioned problem, the invention of claim 1 is a memory system connected to a host computer, wherein a first nonvolatile memory storing information to be protected and an access to the first nonvolatile memory are provided. a first controller for controlling a plurality of essential information and a plurality of operation result and the second non-volatile rewritable storing in association with one-to-one needed when the host computer uses the information in the protected A memory and a second controller that controls access to the second non-volatile memory, wherein the memory system stores calculation method information defining a plurality of calculation methods; select operation method and outputs it to the host computer as a selected calculation method, the second controller, the host competent In accordance with the output condition which reflects the state of the over data, output to the host computer as the second plurality of essential information stored in the nonvolatile memory by selecting one of the essential information the selected essential information The output condition includes a condition based on a calculation result obtained by calculating calculation target information by the selected calculation method .

The invention of claim 2 is the memory system according to the invention of claim 1, wherein the operation information is information reflecting a state of the host computer.

The invention of claim 3 is the memory system according to claim 1 or 2, wherein the protection target information includes a progress status of the protection target information when executed by the host computer. It is defined as a plurality of stages, and the state of the host computer includes the state of the host computer when the host computer is executing any one of the plurality of stages .

According to a fourth aspect of the present invention, there is provided a memory system according to any one of the first to third aspects , wherein the memory system is responsive to a state of the host computer when a request is made from the host computer. Thus, one calculation method is selected as the selected calculation method from the plurality of calculation methods.

A fifth aspect of the present invention is the memory system according to any one of the first to fourth aspects , wherein the selected calculation method is selected according to a progress status of the information to be protected in the host computer. Is done .

The invention according to claim 6 is the memory system according to claim 5 , wherein the second controller is notified when the progress status of the information to be protected in the host computer is notified. The progress status is stored in the second nonvolatile memory as progress history information, and the selected calculation method is selected according to the progress history information.

The invention of claim 7 is the memory system according to any one of claims 1 to 6 , wherein the output condition is an output order when the second controller outputs the plurality of indispensable information. including.

The invention according to claim 8 is the memory system according to claim 7 , wherein the output order follows the order of progress of the information to be protected in the host computer.

The invention according to claim 9 is the memory system according to claim 7 or 8 , wherein the second controller outputs the output in accordance with output history information when the indispensable information is output to the host computer. Select indispensable information to be output next time in order .

The invention according to claim 10 is the memory system according to any one of claims 1 to 9 , wherein the selected calculation method is read from the calculation method information in a plurality of times.

An eleventh aspect of the invention is a memory system according to any one of the first to tenth aspects of the invention, wherein the calculation method information is stored in the second nonvolatile memory.

According to a twelfth aspect of the present invention, there is provided a memory system connected to a host computer, wherein a plurality of indispensable information and a plurality of calculation results required when the host computer uses information to be protected are paired. A rewritable nonvolatile memory for storing calculation method information defining a plurality of calculation methods and controlling access to the non-volatile memory while controlling one of the plurality of calculation methods. Is selected and output to the host computer as a selected computation method, and one essential information from a plurality of essential information stored in the non-volatile memory according to an output condition reflecting the state of the host computer the select and a controller for outputting to the host computer as the selected essential information, before Output conditions include conditions based on a calculation result obtained by calculation by the target select operation method operand information.
The invention of claim 13 is the memory system according to the invention of claim 12, wherein the protection target information includes a plurality of progress states of the protection target information when executed by the host computer. The state of the host computer is defined as a stage, and includes the state of the host computer when the host computer is executing any one of the plurality of stages .

The invention of claim 14 is an information protection method for protecting information to be protected stored in a first nonvolatile memory of a memory system connected to a host computer, wherein the rewritable second nonvolatile memory is used. a step of storing in association with one-to-one more essential information and a plurality of operation result and the necessary when the host computer uses the information in the protected, calculation method information defining a plurality of calculation methods , A step of selecting one calculation method from the plurality of calculation methods and outputting the selected calculation method to the host computer, and a calculation obtained by calculating calculation target information by the selected calculation method depending on the result output condition which reflects the state of the host computer including, or multiple essential information stored in the second nonvolatile memory Select 1 of essential information and a step of outputting to the host computer as the selected essential information.
The invention according to claim 15 is the information protection method according to claim 14, wherein the protection target information includes a plurality of progress states of the protection target information when executed by the host computer. The state of the host computer includes the state of the host computer when the host computer is executing any one of the plurality of stages .

According to the first to eleventh aspects of the present invention, a plurality of indispensable information required when the host computer uses information to be protected and a plurality of calculation results are stored in a one-to-one association with each other. 2 non-volatile memory and a second controller for controlling access to the second non-volatile memory , storing operation method information defining a plurality of operation methods, and selecting one operation method from the plurality of operation methods As a selected calculation method, the second controller outputs one to the host computer according to the output condition reflecting the state of the host computer, from a plurality of essential information stored in the second non-volatile memory. select vital information is output to the host computer as the selected essential information, output conditions, by the selected calculation method the operand information Including conditions based on a calculation result obtained by calculation. Thereby, the design level of the existing host computer is not required, and the security level can be improved at a low cost. For example, since it can change for every information of protection object, even if security is once broken, it can be reconstructed easily. In addition, since an output condition reflecting the state of the host computer is provided, essential information cannot be read unless it is reproduced, making it more difficult to create a copy.
The inventions according to claims 12 and 13 store a plurality of indispensable information necessary for the host computer to use the information to be protected and a plurality of calculation results in a one-to-one association with each other. A rewritable non-volatile memory for storing calculation method information for defining the calculation method, and a host computer as a selected calculation method by selecting one calculation method from a plurality of calculation methods while controlling access to the nonvolatile memory In response to output conditions reflecting the status of the host computer, one essential information is selected from a plurality of essential information stored in the non-volatile memory and output to the host computer as selected essential information The output condition is a calculation result obtained by calculating the calculation target information by the selected calculation method. Includes a condition-based. Thereby, the design level of the existing host computer is not required, and the security level can be improved at a low cost. For example, since it can change for every information of protection object, even if security is once broken, it can be reconstructed easily. In addition, since an output condition reflecting the state of the host computer is provided, essential information cannot be read unless it is reproduced, making it more difficult to create a copy.
The inventions described in claims 14 and 15 include a plurality of indispensable information and a plurality of calculation results required when the host computer uses information to be protected in the rewritable second nonvolatile memory. A step of storing in a one-to-one relationship, a step of storing calculation method information defining a plurality of calculation methods, and a step of selecting one calculation method from the plurality of calculation methods and outputting the selected calculation method to the host computer And 1 from a plurality of essential information stored in the second nonvolatile memory according to the output condition reflecting the state of the host computer including the operation result obtained by calculating the operation information by the selected operation method. And selecting the essential information and outputting it to the host computer as selected essential information. Thereby, the design level of the existing host computer is not required, and the security level can be improved at a low cost. For example, since it can change for every information of protection object, even if security is once broken, it can be reconstructed easily. In addition, since an output condition reflecting the state of the host computer is provided, essential information cannot be read unless it is reproduced, making it more difficult to create a copy.

It is a figure which shows a computer system provided with the memory system which concerns on this invention. It is a figure which illustrates the storage area of the memory array of ROM. It is a figure which illustrates the storage area of the memory array in a 1st embodiment, and the information stored in each storage area. 3 is a flowchart showing the operation of the memory system in the first embodiment. 3 is a flowchart showing the operation of the host computer in the first embodiment. 3 is a flowchart showing the operation of the host computer in the first embodiment. It is a figure which illustrates the storage area of the memory array in a 2nd embodiment, and the information stored in each storage area. 6 is a flowchart showing the operation of the memory system in the second embodiment. It is a flowchart which shows operation | movement of the host computer in 2nd Embodiment. It is a flowchart which shows operation | movement of the host computer in 3rd Embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.

<1. First Embodiment>
FIG. 1 is a diagram showing a computer system including a memory system 1 according to the present invention. The computer system includes a memory system 1 according to the present invention and a host computer 10 having a function as a general computer.

  The memory system 1 includes a ROM 2 which is a read-only storage device, and a memory system 3 configured as a readable / writable storage device so that, for example, user data can be saved as necessary. Although details are not shown, the memory system 1 in the present embodiment is configured to be detachable from the host computer 10. Examples of such a memory system 1 include a memory card and a game cassette, but are not limited thereto.

  The ROM 2 includes a controller 20 and a memory array 21. The controller 20 has a function of reading various data stored in the memory array 21 and outputting it to the host computer 10 in response to a request from the host computer 10. Further, the controller 20 provides a security function for data stored in the memory array 21 with the host computer 10. Since various methods conventionally proposed as the security function provided by the controller 20 can be adopted as appropriate, detailed description will be omitted below.

  FIG. 2 is a diagram illustrating a storage area of the memory array 21 of the ROM 2. The memory array 21 has a structure in which a plurality of nonvolatile storage elements are regularly arranged, and is divided into a plurality of storage areas as shown in FIG.

  As the memory elements constituting the memory array 21 in the present embodiment, elements in which data cannot be written by the host computer 10 are employed. Accordingly, the ROM 2 is configured as a read-only storage device in the memory system 1 as described above. However, the storage device that stores the program 26 and the like is not necessarily read-only.

  As shown in FIG. 2, the storage area of the memory array 21 includes a unique key storage area 22 for storing key information 25, a program storage area 23 for storing a program 26, and contents (images, sounds, texts) used by the program 26. Etc.) is defined. However, the storage area to be defined is not limited to this, and other storage areas (for example, an area in which data for providing the security function is stored) may be defined.

  The key information 25 that is the operation information is a unique value for identifying the program 26, and for example, a value used for a security function provided by the controller 20 is assumed.

  In the present embodiment, the key information 25 uses a different value for each title of the program 26, such as a product code. That is, if the program 26 is a game program, the key information 25 is specific to the game title, and the same value is used for game programs with the same title. However, for example, different values may be adopted as the key information 25 even if the programs 26 have the same title, such as a serial number.

  Although details will be described later, the key information 25 in the present embodiment is read by the host computer 10 and stored in a specific address (hereinafter referred to as “key address”) of the storage device 12 of the host computer 10. The That is, if the memory system 1 is attached to a regular host computer 10, the key address is always constant.

  The program 26 is information to be protected and is executed by the host computer 10. In the program 26, the progress of the program 26 when executed by the host computer 10 is defined by a marker code or the like. In the following description, it is assumed that N stages (stage 1,..., N) are sequentially defined in the program 26 as the progress status of the program 26 (N is a natural number of 2 or more). ). That is, the host computer 10 can acquire the progress status of the program 26 being executed as the stage n (n is a natural number from 1 to N) while the program 26 is being executed.

  Although details will be described later, when the host computer 10 uses the key information 25 as the operation information, the program 26 according to the present embodiment directly reads a key address (fixed address) from the storage device 12. It is described in. Therefore, if the value read as the key information 25 by the key address is truly the value of the key information 25, the information stored in the key address is not rewritten in the host computer 10. It is shown that. That is, the key information 25 in the present embodiment is information reflecting the state of the host computer 10. Further, the information to be protected in the present embodiment is not only the program 26 but also all information stored in the memory array 21.

  The memory system 3 includes a controller 30 and a memory array 31. The controller 30 has a function of reading various data stored in the memory array 31 and outputting the data to the host computer 10 in response to a request from the host computer 10, and a function of storing various data in the memory array 31. ing. The function and operation of the controller 30 in the present embodiment will be described later.

  FIG. 3 is a diagram illustrating a storage area of the memory array 31 and information stored in each storage area in the first embodiment. The memory array 31 is composed of a plurality of nonvolatile storage elements and is divided into a plurality of storage areas as shown in FIG.

  As a storage area of the memory array 31 in the present embodiment, a data save area 32, a calculation method storage area 33, an indispensable information storage area 34, a first table storage area 35, and a second table storage area 36 are defined. . However, the storage area to be defined is not limited to this, and other storage areas may be defined as necessary.

  As the memory elements constituting the memory array 31, elements that can be written as well as data are employed. Therefore, the memory system 3 is configured as a readable / writable storage device in the memory system 1 as described above.

  The data save area 32 is a storage area for storing the save data 320 and can be freely accessed by the host computer 10 (user). Here, “can be freely accessed” means that access can be made regardless of the security function according to the present invention.

  The save data 320 is mainly information created by the user, information for resuming the program 26 from the middle (information when the game is interrupted halfway), and content information acquired by the user. (Image, sound, text, etc.). However, the save data 320 may be information automatically created by the host computer 10, for example, without depending on an instruction from the user.

The calculation method storage area 33 is an area for storing calculation method information 330. The calculation method information 330 includes information defining a plurality of calculation methods set for each stage n (showing the progress of the program 26 as described above). In the following description, the calculation method corresponding to stage n is referred to as “calculation method f _n (x)”. As the calculation method f _n (x), for example, a checksum value or hash value of “x” can be calculated. However, the calculation method is not limited to these.

  Here, “x” is the value of the operation information, and in the present embodiment, the value read from the key address as described above (or the value of the key information 25 if normal) is used. Therefore, in the present embodiment, the information to be calculated differs for each program 26, but is fixed regardless of the progress of the program 26 (the host computer 10 in this embodiment rewrites the value stored in the key address). Not because.)

  The information to be calculated is not limited to the key information 25. For example, other values and calculation methods stored in a specific address in the storage device 12 of the host computer 10 or the memory array 21 of the ROM 2 can be used. The value of information to be configured may be employed, or may not be a fixed value while the program 26 is in progress. However, the operation information is a value that can be predicted by the program 26 as long as normal processing is performed, and is preferably information that reflects the state of the host computer 10. Furthermore, it is preferable that the operation information is information whose state changes when the program 26 is falsified or illegally copied.

The indispensable information storage area 34 is a storage area in which the indispensable information 340 is stored. In the memory system 1, information indispensable for the host computer 10 to advance the program 26 is defined for each stage n, and these are stored as indispensable information 340 in the indispensable information storage area 34. In the following description, indispensable information corresponding to stage n is referred to as “E _n ”. That is, the indispensable information 340 includes a plurality of indispensable information E ₁ ,..., E _N corresponding to the stages 1,.

The essential information E _n, for example, character data, or a portion thereof and that is required to advance the program 26, information concerning decryption key information stored encrypted is assumed in the ROM2 The Further, only a part of the calculation method f _n (x) may be stored in the calculation method information 330 so that the calculation method f _n (x) is expressed together with the information E _(n−1). . Alternatively, a command (described later) for reading the calculation method f _n (x) from the memory system 3 at the stage n may be used as indispensable information E _(n−1) corresponding to the stage (n−1).

In the following, essential information E _n, in the case of executing the program 26 will be described as the information necessary only for the progress of the stage n. That is, in the present embodiment, in a case of advancing the stage n, the host computer 10, while it is necessary to obtain the essential information E _n from the memory system 1, Stage 1 immediately before, ..., The indispensable information E ₁ ,..., E _(n−1) acquired in _(n−1) need not be stored in the storage device 12 or the like.

  In the following description, it is assumed that the indispensable information 340 is already stored in the indispensable information storage area 34 of the memory array 31 when the memory system 1 is shipped.

The first table storage area 35 is a storage area for storing the first table 350. The first table 350 is information that associates a command to read calculation method f _n (x), and an operation method f _n (x). In the following description, a command for reading the calculation method f _n (x) is referred to as “command R _n ”. Although details will be described later, when the controller 30 receives the command R _n from the host computer 10, the controller 30 refers to the first table 350 and selects the calculation method f _n (x) corresponding to the received command R _n as the selected calculation method. The selected calculation method is read from the calculation method information 330 and output to the host computer 10.

In the present embodiment, the command R _n is described in the program 26, and the host computer 10 sends the command R ₁ ,... Corresponding to the progress status (stage 1,..., N) of the program 26. .., it is described as acquiring a R _N. That is, since the command R _n is selected according to the progress of the program 26 in the host computer 10, the selected command R _n reflects the state of the host computer 10. However, the command R _n is not limited to that provided in such a form. For example, as previously described, the command R _2, · · ·, R _N is essential information E _1, · · ·, may be included in the essential information 340 as E _(N-1).

The second table storage area 36 is a storage area for storing the second table 360. The second table 360 is a calculation result (not shown in FIG. 3) obtained by calculating the key information 25 (information to be calculated) by the calculation method f _n (x) and the necessary information 340. is information that associates the essential information E _n. In the following, by using the calculation method f _n (x) that has been successfully read by the command R _n at stage n, the normal operation results of calculation to be operational information (if normal key information 25) " This is referred to as “calculation result _An ”. On the other hand, a calculation result obtained by calculation at stage n and not yet judged whether it is normal or not is referred to as “calculation result QA _n ”.

Although details will be described later, the controller 30, the host computer 10, when there is a request for access to essential information 340 (when receiving a command to read the essential information E _n), the operation result is input together with the request QA The second table 360 is referred to using _n . When the operation result A _n matching the result of the calculation QA _n is present, the essential information E _n associated with the operation result A _n is selected as the selected essential information, essential information 340 ( The selected indispensable information is read from the indispensable information storage area 34) and output to the host computer 10. That is, in this embodiment, the operation result A _n matching operation result QA _n is an output condition of the essential information to be present in the second table 360. In the following description, the host computer 10, a command to be issued to read the essential information E _n from essential information 340 is referred to as a "request command".

  Returning to FIG. 1, the host computer 10 includes a CPU 11 that performs various data calculations and controls various hardware included in the host computer, and a storage device 12 that stores various data. Accordingly, the host computer 10 has a configuration and functions as a general computer. Further, the host computer 10 has a slot (not shown), and the memory system 1 can be mounted in the slot.

  The CPU 11 of the host computer 10 reads out data stored in the memory array 21 of the memory system 1 from the ROM 2 and performs various calculations.

  In particular, the CPU 11 has a function of executing the program 26 stored in the program storage area 23 while loading it into the storage device 12 via the controller 20. Further, as described above, the CPU 11 stores the key information 25 stored in the unique key storage area 22 in the area indicated by the key address of the storage device 12. Further, the CPU 11 grasps the progress status (the stage in progress) of the program 26 being executed while executing the program 26, and stores the progress status (stage identifier) in the storage device 12 if necessary.

  Further, the CPU 11 has a function of accessing the memory array 31 via the controller 30.

For example, the CPU 11 issues a command R _n to the memory system 1 (controller 30) according to the progress status (stage n) of the program 26 being executed. As a result, the host computer 10 can read the calculation method f _n (x) from the memory system 3. Further, the calculation result QA _n is obtained using the read calculation method f _n (x) and the operation information (key information 25 if normal), and is output to the memory system 1 (controller 30) together with the request command. As a result, information En that is indispensable for advancing stage _n is acquired.

  The storage device 12 is a RAM (generally a volatile storage device that can be accessed at high speed) used as a temporary working area of the CPU 11, and a startup program (not shown) of the host computer 10. ) And the like for storing read-only ROM. Although not shown in FIG. 1, part or all of the storage device 12 may be inside the CPU 11 in order to enhance the security function.

  Although not shown in detail, the host computer 10 includes an output device (display, LED, speaker, printer, etc.) that outputs information to the user, and an input device (keyboard or button) that the user operates to input information. , A controller, a microphone, a touch panel, and the like) may be provided as appropriate.

  The above is the description of the configuration and functions of the computer system including the memory system 1. Next, the information protection method in the present embodiment will be described while explaining the operation of the computer system.

  FIG. 4 is a flowchart showing the operation of the memory system 3 in the first embodiment. The memory system 3 operates in a state where the memory system 1 is mounted on the host computer 10 that is being activated. In the following description, the conventional technique can be applied to the operation of the controller 20 of the ROM 2, and thus the description thereof will be omitted as appropriate.

  While the memory system 1 is operating, the controller 30 of the memory system 3 is ready to accept various commands from the host computer 10 (steps S1, S3, S5, S8). Hereinafter, a state in which the controller 30 can accept a command from the host computer 10 is referred to as a “standby state”. However, the commands received by the controller 30 are not limited to those shown in FIG.

  When a load command is input in the standby state (Yes in step S1), the controller 30 loads the save data 320 stored in the data save area 32 of the memory array 31 (step S2). More specifically, the save data 320 specified by the address (address of the data save area 32) input together with the load command is read from the memory array 31 and output to the host computer 10.

  When a save command is input in the standby state (Yes in step S3), the controller 30 saves data in the data save area 32 of the memory array 31 (step S4). More specifically, information (information to be saved, for example, user data) input together with the save command is written as save data 320 at an address input with the save command (address of the data save area 32).

  As described above, in the present embodiment, the controller 30 does not perform special processing for reading and writing of the save data 320, and performs processing equivalent to the conventional one. However, the host computer 10 in the present embodiment includes information indicating the progress status (stage n) of the program 26 when the save data 320 is saved in the save data 320. In other words, the program 26 in the present embodiment is described so that when the save data 320 is created (updated) during execution, information indicating the progress status at that time is included in the save data 320. Hereinafter, information indicating the stage n included in the save data 320 (indicating the stage resumed by the save data 320) is referred to as “stage S”.

When the command R _n is input in the standby state (Yes in step S5), the controller 30 refers to the first table 350 in the first table storage area 35 (step S6).

Here, the information read from the first table storage area 35 (first table 350) is an address indicating a position where the calculation method f _n (x) corresponding to the input command R _n is stored. Although not shown in FIG. 4, when the input command R _n is not stored in the first table 350 (that is, when an incorrect command R _n is input), the controller 30 Dummy data is output to the computer 10. However, instead of outputting dummy data, processing such as returning an error, limiting the subsequent operation, or not accepting anything may be performed.

Next, the controller 30 reads the information stored in the calculation method storage area 33 indicated by the read address and outputs it to the host computer 10. The information stored in the calculation method storage area 33 is information representing the calculation method f _n (x) included in the calculation method information 330. Thus, when the command R _n is input from the host computer 10, the controller 30 selects the calculation method f _n (x) corresponding to the command R _n as the selected calculation method and outputs it to the host computer 10 ( Step S7).

As described above, since the command R _n is selected according to the stage n (reflecting the state of the host computer 10), the command R _n is the state of the host computer 10 when the command R _n is output. It is information reflecting. The controller 30 selects the calculation method f _n (x) from the plurality of calculation methods f ₁ (x),..., F _N (x) in response to the command R _n. Depending on the state of the host computer 10 when there is a request from 10, the calculation method f _n (x) of the calculation method information 330 is selected as the selected calculation method.

With this configuration, a person who intends to read the calculation method f _n (x) illegally does not reproduce the state of the normal host computer 10 that changes every moment, so that the calculation method f _n (x ) Cannot be read and the security level is improved.

  When a request command is input in the standby state (Yes in step S8), the controller 30 refers to the second table 360 in the second table storage area 36 (step S9).

When a request command is input, together with the command, computation obtained in the host computer 10 results QA _n is also inputted. Controller 30, the operation result A _n matching operation result QA _n retrieves the second table 360 or not stored. When the operation result A _n matching operation result QA _n is stored, the controller 30 reads the address associated with the operation result A _n. In the second table 360, and the address associated with the operation result A _n, a storage address of essential information E _n corresponding to the result A _n.

Next, the controller 30 reads the information indicated by the storage address read from the second table 360 from the essential information storage area 34 and outputs it to the host computer 10. With the information stored in the essential information storage area 34, i.e., an essential information E _n contained in the essential information 340. In this manner, when a request command from the host computer 10 is inputted, the controller 30, the first essential information corresponding to the operation result A _n matching operation result QA _n input together with the request command E _n Is selected as essential information to be selected and output to the host computer 10 (step S10).

As described above, the operation information in the present embodiment is information reflecting the state of the host computer 10. Therefore, the calculation result QA _n calculated using the calculation target information is also information reflecting the state of the host computer 10. Then, the controller 30, as the output condition for the selected essential information, by using a calculation result QA _n reflecting the state of the host computer 10, who contemplates trying Daso read illegally essential information 340 every moment If the normal state of the host computer 10 that changes is not reproduced, the essential information 340 cannot be read, and the security level is improved. Incidentally, when the result A _n matching the calculation result QA _n which are input together with the request command is not stored in the second table 360, the controller 30 outputs the dummy data. However, instead of outputting dummy data, processing such as returning an error, limiting the subsequent operation, or not accepting anything may be performed.

  The above is the operation of the memory system 3. Next, the operation of the host computer 10 will be described.

  5 and 6 are flowcharts showing the operation of the host computer 10 in the first embodiment. In the following description, it is assumed that the memory system 1 is already installed in the host computer 10 and the controller 30 is in a standby state. Moreover, each process shown by FIG. 5 and FIG. 6 shows the process performed when CPU11 of the host computer 10 mainly operate | moves according to the program 26 unless there is particular notice.

  When the host computer 10 starts executing the program 26, the host computer 10 acquires the key information 25 from the ROM 2 of the memory system 1 (step S11) and stores it in the key address of the storage device 12. Then, “1 (initial stage)” is set in the stage n indicating the progress of the program 26 (step S12). As a result, the progress status of the program 26 being executed in the host computer 10 shifts to stage 1 and stage 1 is started.

Next, the host computer 10 issues a command R _n to the memory system 1 (controller 30). As a result, the calculation method f _n (x) (selected calculation method) is acquired from the memory system 1 as described above (step S13). As described above, the command R _n used in the stage n is acquired from the memory array 21 of the ROM 2 by the host computer 10.

When the calculation method f _n (x) is acquired, the host computer 10 reads the value stored in the key address of the storage device 12 as calculation information, and the calculation method acquired in step S13 is the calculation information. An operation result QA _n is obtained by calculation using f _n (x) (step S14).

Next, the host computer 10, together with the request command, and outputs the operation result QA _n obtained in step S14 to the memory system 1 (controller 30). Thus, essential information from the memory system 1 E _n (the selected essential information) is obtained as previously described (step S15).

When acquiring the essential information E _n, the host computer 10, while advancing the stage n programs 26 (step S20), the state of monitoring the various states (step S21, S24, S26, S29) . However, the state monitored by the host computer 10 is not limited to the state shown in FIG. Hereinafter, a state in which the host computer 10 is monitoring various states is referred to as a “monitoring state”.

  In the monitoring state, when a data load (reading of information stored in the data save area 32 of the memory array 31) is instructed (Yes in step S21), the host computer 10 sends the controller 30 of the memory system 1 to the controller 30. , Output the load command. When the load command is received from the host computer 10, the controller 30 loads the data as described above and outputs the save data 320 to the host computer 10. Thereby, the host computer 10 acquires the save data 320 (step S22).

  When the save data 320 is acquired, the host computer 10 sets S to n based on the information regarding the stage S to be resumed included in the acquired save data 320 (step S23). As a result, the progress status of the program 26 shifts to the stage where the program 26 is resumed from the stage before data loading (ie, stage S). When the stage S is resumed, the host computer 10 returns to the process of step S20 in order to advance the program 26 in accordance with the loaded save data 320.

In this embodiment, as described above, essential information E _n is the information necessary only for the progress of the stage n. However, even when the defined such information as essential information E _n, even when the resumed program 26 from stage S to get the save data 320, before terminating the stage S from resuming point , it can also occur in having to use the essential information E _S.

For example, essential information E _n is a part of the character data appearing only in stage n, from resuming point to the Stage S is completed, if the characters appear, the problems. In such a case, the indispensable information E _S acquired when the stage S is started together with the information regarding the stage S is also included in the save data 320 and saved from the loaded save data 320. _What is necessary is just to comprise so that _S may be acquired.

However, the data save area 32 in the present embodiment is configured as a storage area that can be accessed relatively freely. Therefore, the inclusion of essential information E _S to save data 320, there is a risk that the security function is reduced somewhat. Therefore, the information that does not cause the above problem (not used in stage S after resumption information), is preferably defined as an integral information E _n. As such information, for example, information that is used immediately after the information E _S that is indispensable in the stage S is used and is not used thereafter is preferable. As such information, for example, a program code of a process executed only once immediately after the execution of step S15 can be considered.

Alternatively, immediately after executing the step S23, and executes the process corresponding to step S13 to S15, it may obtain essential information E _S at stage S.

  In the monitoring state, when data saving is instructed (Yes in step S24), the host computer 10 sends to the controller 30 of the memory system 1 information to be saved together with a save command (save data. Information on stage n at the time of saving). Is output) (step S25). As a result, the controller 30 saves the data as described above. The data saving instruction to the host computer 10 may be given by the user, or the execution timing may be determined in advance by the program 26 as in auto saving.

  In the monitoring state, when the program 26 proceeds and stage n ends (Yes in step S26), the host computer 10 determines whether or not the current stage n is the final stage N (step S27).

  If the current stage n is the final stage N, it is determined that the program 26 has progressed to the end, and the program 26 is terminated. On the other hand, if the current stage n is not the final stage N, the stage n is incremented (step S28), the next stage is started, and the process returns to step S13.

  When the end is instructed in the monitoring state (Yes in step S29), the host computer 10 ends the execution of the program 26. Although details are omitted, it is preferable to confirm with the user whether or not to save data when an end is instructed.

  The above is the description of the information protection method in the first embodiment. Next, the effect in this embodiment will be verified.

In the memory system 1, information to be protected is stored in the memory array 21 of the ROM 2 and the memory array 31 of the memory system 3, respectively. The program 26 stored in the ROM 2 cannot operate normally in the host computer 10 without the essential information E ₁ ,..., E _N stored in the memory system 3. It is configured. That is, a person who intends to illegally duplicate the program 26 (hereinafter referred to as “illegal duplicator”) need only break the security function of the ROM 2 and duplicate the information stored in the memory array 21. First, the security function provided by the controller 30 of the memory system 3 must also be considered, and all the information stored in the memory array 31 must be read and copied.

Here, in order to read out all the essential information E ₁ ,..., E _N from the memory array 31 via the controller 30, the external computer (not limited to the host computer 10). (Including the computer used by the duplicator) is not sufficient to output the request command to the controller 30. Since this request command is stored in the ROM 2, it may be reproduced simply by copying the information stored in the memory array 21. However, even if this request command is randomly given to the controller 30, it is indispensable. such information E _n can not be read.

As described above, the external computer needs to output all normal calculation results A ₁ ,..., A _N to the controller 30 one by one together with the request command. The calculation result _An is not stored in the ROM 2 but only stored in the memory system 3 (second table storage area 36). Therefore, the operation result of A _n because it can not be duplicated from the ROM 2, are still not able to break through the security features of the memory system 3 illegal duplication's operation result A _1, · · ·, respectively calculating the A _N There is nothing but to ask for.

The calculation result _An is obtained as a result of calculating the calculation target information by the calculation method f _n (x). Therefore, in order to obtain all the calculation results A ₁ ,..., A _N , the external computer acquires the operation information and all the f ₁ (x),..., F _N (x). There must be. In the present embodiment, the operation information (key information 25) is stored in the ROM 2, but the operation method f _n (x) is stored only in the memory system 3 (operation method storage area 33). Therefore, since the calculation method f _n (x) cannot be read from the ROM 2, an unauthorized duplicator who has not yet broken through the security function of the memory system 3 can execute all commands R _{1 ,.} Must be output to the controller 30 one by one and read from the memory system 3.

That is, in the memory system 1, in order to read out all the essential information E ₁ ,..., E _N , the security function of the ROM 2 is broken and the information stored in the memory array 21 is read and analyzed. all commands R ₁ and operand information, ... we must identify and R _N.

Further, as described above, since the operation information and all the commands R ₁ ,..., _RN are information reflecting the state of the host computer 10, an unauthorized duplicator can identify the specified operation When the information and all the commands R ₁ ,..., _RN are used, the normal state of the host computer 10 must be reproduced.

Further, the operation information and all the commands R ₁ ,..., R _N can be easily changed by a regular programmer (provider of the program 26) according to the program 26, and can be changed in the host computer 10. Is not required. Therefore, for example, it can be changed frequently for each game title or revision, and an unauthorized duplicator must perform the above analysis work each time, and it is constant until an illegal duplicate (pirated version) is manufactured. The above time will be required. In particular, when the program 26 is game software or the like, there is a characteristic that if the pirated version is distributed immediately after the start of the sale, the sales of the regular version will be greatly affected. Therefore, in such products on the market, even if it is not possible to completely prevent the production of pirated copies, it can be said that the effect is great if the appearance of pirated copies can be delayed for a certain period from the start of release.

  As described above, the memory system 1 according to the first embodiment is connected to the host computer 10 and includes the memory array 21 that stores the program 26, the controller 20 that controls access to the memory array 21, and the host computer 10. A rewritable memory array 31 that stores essential information 340 required when using the program 26 and a controller 30 that controls access to the memory array 31 are provided. Then, the controller 30 outputs the indispensable information 340 stored in the memory array 31 to the host computer 10 as selected indispensable information according to the output condition reflecting the state of the host computer 10. Thereby, the design level of the existing host computer 10 is not required, and the security level can be improved at a low cost. For example, since it can change for every program 26, even if security is once broken, it can be reconstructed easily. In addition, since an output condition reflecting the state of the host computer is provided, essential information cannot be read unless it is reproduced, making it more difficult to create a copy.

Further, the memory system 1, the operation method stores a calculation method information 330 that defines the f _n (x), and outputs a calculation method f _n (x) to the host computer 10 as the selected calculation method, it must be selected The indispensable information output condition includes a condition based on a calculation result QA _n obtained by calculating information to be calculated (information stored in a storage area indicated by a key address) by a selected calculation method. In this way, by making information created by computation as necessary as an output condition, information stored in any storage area (fixed information) is used as it is as an output condition. , Improve the security level.

The calculation method information 330 defines a plurality of calculation methods f ₁ (x),..., F _N (x), and the memory array 31 stores a plurality of indispensable information E ₁ ,. , E _N are stored, and a plurality of calculation results A respectively obtained by one calculation method f _n (x) selected from a plurality of calculation methods f ₁ (x),..., F _N (x). ₁ ,..., A _N and a plurality of indispensable information E ₁ ,..., E _N are associated with each other in a one-to-one relationship. _One selected essential information from E ₁ ,..., E _N is selected and output to the host computer 10. As a result, the security level is improved as compared with the case where all the essential information 340 is read by _one calculation result A ₁ obtained by one calculation.

  Further, the selected calculation method is selected according to the progress status of the program 26 in the host computer 10, so that the indispensable information 340 can be read unless a read request linked to the progress status of the program 26 is made. It becomes difficult. This improves the security level.

  The calculation method information 330 is stored in the memory array 31. Since the security function of the memory system 3 has not been broken, the security level is improved as compared with the case where the calculation method information 330 is stored on the ROM 2 side.

  Although the host computer 10 has been described as being freely accessible to the data save area 32, some security function may be provided for access from the host computer 10 to the data save area 32. The same applies to the following embodiments.

In the first embodiment, a plurality of calculation methods f _n (x) are defined in the calculation method information 330, but one calculation method may be defined. Even in this case, since the security function is added to the memory system 3, the security level is improved as compared with the conventional technology. Even if only one calculation method is defined in the calculation method information 330, it is not necessary to change the design of the existing host computer 10 and it can be easily changed according to the information to be protected. There is also an effect that there is.

  Further, each of the storage areas shown in FIG. 2 and FIG. 3 is shown to be composed of continuous addresses in the memory arrays 21 and 31. However, for example, the unique key storage area 22 may be configured with discontinuous addresses. The same applies to the following embodiments.

<2. Second Embodiment>
In the first embodiment, calculation method f _n (x) and essential information E _n is associated with the progress in the host computer 10 of information to be protected (stage n), a calculation method in stage n Only f _n (x) and essential information E _n can be read out. However, for example, the order in which the calculation method f _(n-1) (x) and the calculation method f _n (x) are read out is not particularly limited. However, for example, it is also possible to restrict the reading order of the plurality of calculation methods f ₁ (x),..., F _N (x) and to prohibit the reading when the restrictions are not complied with. The same applies to the essential information E _n.

  FIG. 7 is a diagram illustrating a storage area of the memory array 31 and information stored in each storage area in the second embodiment. In the memory system 1 according to the second embodiment, the same components as those in the memory system 1 according to the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  As is clear from comparison between FIG. 7 and FIG. 3, the memory system 1 in the second embodiment has a memory area provided in the memory array 31 of the memory system 3 in the memory system 1 in the first embodiment. Is different. Specifically, the memory array 31 in the second embodiment is additionally provided with a progress history storage area 37 for storing progress history information 370 and an output history storage area 38 for storing output history information 380. ing.

  In addition, in the first embodiment, the information stored in the first table storage area 35 is the first table 351 and the information stored in the second table storage area 36 is the second table 361. Different from the memory system 1.

  The progress history information 370 stored in the progress history storage area 37 is information created by the controller 30 and is notified when the controller 30 is notified of the progress status (stage n) from the host computer 10. It is information that records the progress. Although details will be described later, in the present embodiment, when the stage 26 (n-1) in the program 26 proceeds normally normally and the stage n is started normally, the progress history information 370 includes the stage n. To be recorded. In other words, the state in which the stage n is recorded in the progress history information 370 indicates that the progress state of the program 26 being executed by the host computer 10 is in the stage n state. In the following description, the stage recorded in the progress history information 370 is referred to as “stage P”.

The output history information 380 stored in the output history storage area 38 is created by the controller 30. Output record information 380, when the controller 30 outputs the essential information 340 to the host computer 10 is information that records information about the essential information E _n to be output. In this embodiment, sequentially proceeded successfully programmed 26 to stage n, in the state in which to essential information E _n at stage n is outputted successfully, stage n is recorded in the output history information 380 Yes. In the following description, the stage recorded in the output history information 380 is referred to as “stage Q”. The initial value of the stage Q in the output history information 380 is “0”.

First table 351 in the second embodiment, the command R _n and the command R _n in the corresponding address (the command R _n calculation method storage area calculation method f _n (x) is stored to be read by the 33 address) is the same as the first table 350 in the first embodiment. However, in addition to these pieces of information, the first table 351 also associates information on the stage n where each command R _n should be used for all the commands R _n . That is, the first table 351 is associated with a command R _n, a stage n to command R _n is used, and a storage address of the calculation method f _n (x) to be read by the command R _n.

Second table 361 in the second embodiment, the operation result A _n, when the operation result QA _n address corresponding to the operation result A _n (the result of the calculation to match the A _n is inputted with the request command is that essential information E _n to be read is in association with necessary address essential information storage area 34) stored is the same as the second table 360 in the first embodiment. However, in addition to these pieces of information, the second table 361 is also associated with information related to the progress of the program 26 (stage n). That is, the second table 361, a stage n, a calculation result A _n (predicted value of the operation result QA _n when calculating normally in the stage n has been performed), essential that corresponds to the operation result A _n stores are associated with the address of such information E _n.

  Next, an information protection method in the second embodiment will be described.

  FIG. 8 is a flowchart showing the operation of the memory system 3 in the second embodiment. The memory system 3 in the second embodiment operates in a state where the memory system 1 is mounted on the host computer 10 that is being activated.

  While the memory system 3 according to the second embodiment is operating, the controller 30 of the memory system 3 is in a state where it can accept various commands from the host computer 10 (steps S30, S33, S36, S42). ). Hereinafter, in the present embodiment, a state in which the controller 30 in the second embodiment can accept a command from the host computer 10 is referred to as a “waiting state”. However, the commands received by the controller 30 are not limited to those shown in FIG.

  When a load command is input in the standby state (Yes in step S30), the controller 30 loads the save data 320 stored in the data save area 32 of the memory array 31 (step S31). Then, from the loaded save data 320, information on the stage resumed by the save data 320 (that is, stage S) is acquired, and the stage S is recorded as the stage P in the progress history information 370, and the output history information The stage (S-1) immediately before the stage S is recorded as a stage Q in 380 (step S32).

  By executing step S32, for example, even when the program 26 has already progressed to the stage n, if the save data 320 to be resumed from the stage (n-1) is loaded, the process proceeds. The stage P in the history information 370 is rewritten to the stage (n-1), and the stage Q in the output history information 380 is rewritten to the stage (n-2). That is, when the progress is reversed by normal processing, the progress history information 370 and the output history information 380 are corrected.

  When a save command is input in the standby state (Yes in step S33), the controller 30 records stage n at this time as stage P in the progress history information 370 (step S34). The stage n recorded in step S34 uses information indicating the stage n included in the information input from the host computer 10 together with the save command.

  When the stage P is recorded in the progress history information 370, the controller 30 saves the information input together with the save command in the data save area 32 of the memory array 31 as in the first embodiment (step S35). In the present embodiment, only the information indicating the stage n may be input from the host computer 10 together with the save command. In that case, since there is no information to be stored in the data save area 32, step S35 is not executed.

When the command R _n is input in the standby state (Yes in step S36), the controller 30 refers to the first table 351 in the first table storage area 35 (step S37). If the input command R _n does not exist in the first table 351 (No in step S38), the input command R _n is regarded as an undefined illegal command and dummy data is output. (Step S39).

On the other hand, when the input command R _n is present in the first table 351 (Yes in step S38), the controller 30 is the information associated with the input command R _n as in the first embodiment. Are read from the first table storage area 35.

Here, the first table storage area 35 and the information read from (first table 351), and information indicating a stage n corresponding to the input command R _n, a calculation method corresponding to the command R _n f _n (x) Storage address. As described above, since the command R _n and the stage n are associated with each other in the first table 351, the host computer 10 outputs the command R _n to the controller 30 to change the state (stage n) of the host computer 10. It can be transmitted to the controller 30 indirectly.

Next, if the stage n acquired from the first table 351 matches the stage P recorded in the progress history information 370 (Yes in step S40), the controller 30 stores the storage acquired from the first table 351 together with the stage n. Using the address, the calculation method f _n (x) stored at the storage address is read and output to the host computer 10 (step S41).

  On the other hand, when the stage n acquired from the first table 351 is different from the stage P recorded in the progress history information 370 (No in step S40), the controller 30 executes step S39 and outputs dummy data. That is, the controller 30 in this case prohibits the output of the normal selected calculation method.

The situation of No in step S40 means that the progress status of the program 26 in the host computer 10 (the progress status notified in advance to the memory system 3 and recorded in the progress history information 370) is not stage n. This means that the command R _{n to} be used in _n is used. As described above, the controller 30 selects the calculation method f _n (x) while confirming the progress of the program 26 by executing step S40. That is, the controller 30 in the second embodiment selects the selected calculation method according to the progress status (stage n) of the program 26 in the host computer 10.

As described above, if the information protection method according to the second embodiment is adopted, an unauthorized duplicator uses the correct command R _n (the regular command R _n defined in the ROM 2) to configure the memory system 3. The correct calculation method f _n (x) cannot be acquired from the memory array 31 only by attacking. Therefore, it is unlikely that the correct calculation method f _n (x) can be obtained even if the command R _n and the secret information are read from the ROM 2 and output to the controller 30 at random. Compared with the security level.

When a request command is input in the standby state (Yes in step S42), the controller 30 refers to the second table 361 in the second table storage area 36 (step S43), and the calculation result input together with the request command. Whether QA _n is correct or not is determined (step S44).

Also in the first embodiment of the present embodiment similar to the embodiment, the request command is input together with the operation result QA _n. Therefore, the controller 30 searches whether the operation result A _n matching operation result QA _n input is not stored in the second table 361, Resultant value A _n matching the QA _n second table 361 operation results QA _n when that was stored in it is determined that the correct (Yes in step S44).

However, such a determination may cause the following problems. That is, even if the calculation result QA _n is incorrect as the result of the calculation at stage n, it happens to coincide with the predicted value (calculation result A _{(n + 1)} ) at another stage (for example, stage (n + 1)). If so, the calculation result QA _n is mistakenly recognized as correct. Even in this case, it is possible to prevent correct essential information (essential information in stage n) from being read out by post-processing, but it is not very preferable to make an erroneous determination itself.

In order to avoid this, the determination in step S44 is preferably performed as follows, unlike the first embodiment. That is, prior to step S43, the controller 30 acquires the stage P in the progress history information 370 (indicating the progress status of the program 26 at that time). Then, the second table 361 is searched using the acquired stage P with reference to the second table 361. Thus, comparing the second table 361, the predicted value of the operation in stages P (operation result A _n) is obtained, and the operation result A _n, whether or not the input operation result QA _n matches and, only the operation result QA _n is determined to be correct (Yes in step S44) if they match. In this way, it is possible to prevent an erroneous determination by limiting the collation of the input calculation result QA _n to one time. Further, since the controller 30 always manages the progress status of the stage n, it becomes easy to search for a match of the calculation results.

If the operation result QA _n is incorrect, the controller 30 executes a step S39, and outputs the dummy data to the host computer 10 in place of the essential information E _n.

If the operation result QA _n is correct for the hand, the controller 30 reads the stage n corresponding to the operation result A _n consistent with the operation result QA _n from the second table 361. Then, using the stage n read from the second table 361, it is determined whether or not the stage (n−1) matches the stage Q of the output history information 380 (step S45).

  The process in step S45 corresponds to a process of determining whether or not the last stage (stage Q in the output history information 380) from which the indispensable information has been normally read is the immediately preceding stage (stage (n-1)). To do. That is, it is determined as Yes in step S45 only when the essential information 340 has been successfully output in the immediately preceding stage.

When it is determined No in step S45, the controller 30 by executing the step S39, and outputs the dummy data to the host computer 10 in place of the normal essential information E _n.

That is, the controller 30 in the second embodiment, also the operation result QA _n which are input together with the request command in the case where it is determined as "correct", the selected essential outputted to the host computer 10 immediately before If the information is not indispensable information E _(n−1) , it is prohibited to output normal essential information E _n to the host computer 10. Thus, in the second embodiment, in accordance with progression program order 26, unless one request, all essential information E _1, · · ·, be read from the memory array 31 correctly E _N Can not.

On the other hand, if it is determined as Yes at step S45, the controller 30, the address associated with the operation result A _n in the second table 361 (storage address of the operation result A _n in essential corresponding information E _n) first 2 Read from the table 361. Then, using the read the address, and outputs the essential information E _n from essential information storage area 34 to the host computer 10 reads selected as the selected essential information (step S46).

  When normal selected essential information is output to the host computer 10, the controller 30 sets stage n indicating that the selected essential information has been output as the stage Q of the output history information 380, and outputs the output history storage area 38. (Step S47).

  The above is the operation of the memory system 3 in the second embodiment. Next, the operation of the host computer 10 in the second embodiment will be described.

  FIG. 9 is a flowchart showing the operation of the host computer 10 in the second embodiment. Each process shown in FIG. 9 indicates a process executed by the CPU 11 of the host computer 10 mainly operating according to the program 26 unless otherwise specified.

  When the execution of the program 26 is started, the host computer 10 in the second embodiment acquires the key information 25 from the ROM 2 of the memory system 1 (step S51) and stores it in the key address of the storage device 12. Then, “1 (initial stage)” is set in the stage n indicating the progress of the program 26 (step S52). As a result, the progress status of the program 26 being executed in the host computer 10 shifts to stage 1 and stage 1 is started.

  Next, the host computer 10 issues a save command to the memory system 1 together with the stage n indicating the progress of the program 26 (step S53). That is, a save command including stage n is output to the memory system 1. When the process of step S53 is executed, in the memory system 1 to which the save command is input, step S34 is executed as described above, and stage n is stored in the progress history information 370.

  The process of step S53 is a process in which the host computer 10 notifies the memory system 1 of the progress status (stage n) of the program 26. Therefore, step S53 is preferably described in the program 26 so that it is automatically executed by the CPU 11 immediately after stage n is started (without waiting for a user instruction).

  When step S53 is executed and stage n is stored in the progress history information 370 (when there is a normal end notification from the memory system 1), the host computer 10 in the second embodiment performs the processing of steps S54 to S56. Run. In addition, since the process of step S54 thru | or S56 is a process similar to step S13 thru | or S15 in 1st Embodiment, description is abbreviate | omitted. When step S56 is completed, the host computer 10 in the second embodiment executes the same processing as steps S21 to S29 in the first embodiment.

  As described above, also in the second embodiment, the same effect as that in the first embodiment can be obtained.

  In addition, when the progress status of the program 26 in the host computer 10 is notified, the controller 30 in the second embodiment stores the notified progress status in the memory array 31 as progress history information 370 and also progress history. A selected calculation method is selected according to the information 370. Accordingly, the memory system 1 can operate while grasping the state of the host computer 10 and can easily provide a security function reflecting the state of the host computer 10.

Further, in the second embodiment, a plurality of essential information E _1, · · ·, output condition E _N, the controller 30 is integral multiple of the required information E _1, · · ·, outputs E _N Including the output order. That is, if the output order is not included in the output condition, the essential information 340 cannot be read, and the security level is improved.

Further, the controller 30 is indispensable to output the next time so that the output order becomes an output condition according to the output history information 380 when the indispensable information E _(n−) is output to the host computer 10, for example. by selecting the information E _n, easily plurality of essential information E _1, ···, you can determine the output order of E _n.

<3. Third Embodiment>
In the above-described embodiment, when the host computer 10 issues one command R _n , one calculation method f _n (x) is acquired. However, the command R _n for reading the calculation method does not necessarily have a one-to-one correspondence with the calculation method f _n (x).

In the calculation method information 330 in the third embodiment, a plurality of calculation methods f ₁ (x),..., F _N (x) are defined as in the first and second embodiments. Yes. In the third embodiment, the information defining each calculation method f ₁ (x),..., F _N (x) is divided into a plurality of pieces, and sequentially from the memory system 3. It is possible to output to the host computer 10. Then, the host computer 10 divides the data into a plurality of pieces, and creates each calculation method f ₁ (x),..., F _N (x) from the sequentially acquired information.

Hereinafter, the number of divisions of information defining each calculation method f ₁ (x),..., F _N (x) is referred to as a division number M (M is a natural number of 2 or more). Further, each information calculation method f _n of the (x) is divided into M, subscript "m (m is M or less natural number.)" Shows the output sequence from the memory system 3 using a calculation method f _n1 (x),..., f _nM (x). In other words, the calculation method f _n1 (x),..., F _nM (x) is information necessary for creating the calculation method f _n (x) in the host computer 10.

Each calculation method f _n1 (x), ···, a command input from the host computer 10 to request the f _nM (x), the command R _n1, ···, R _nM is in the program 26 Is defined. Then, in the first table 351 in the third embodiment, the command both R _n1 ,, R _nM are associated with stage n, the commands R _n1 ,, R _nM for address calculation method storage area 33 The calculation methods f _n1 (x),..., F _nM (x) are associated one-to-one with the storage addresses.

  Next, an information protection method in the third embodiment will be described. In the information protection method in the present embodiment, the operation in the memory system 1 is almost the same as that in the memory system 1 in the second embodiment, and thus the description thereof is omitted.

  FIG. 11 is a flowchart showing the operation of the host computer 10 in the third embodiment. Each process shown in FIG. 11 indicates a process executed by the CPU 11 of the host computer 10 mainly operating according to the program 26 unless otherwise specified.

  When the host computer 10 according to the third embodiment starts to execute the program 26, the host computer 10 performs steps S61 to S63. Here, the processing of steps S61 to S63 is the same as the processing of steps S51 to S53 in the second embodiment, and thus description thereof is omitted.

  When step S63 is executed, the host computer 10 in the third embodiment sets the value of m indicating the output order to “1 (initial value)” (step S64).

Next, the host computer 10 issues a command R _nm to the controller 30 of the memory system 3, obtains an operation method f _nm (x) output from the memory system 3 and stores it in the storage device 12. Store it (step S65).

If m does not coincide with M (No in step S66), the calculation methods f _n1 (x),..., F _nM (x) necessary to create the calculation method f _n (x) are obtained. Are not yet acquired, m is incremented (step S67), and the processing from step S65 is repeated.

On the other hand, m if matches the M (Yes in step S66), a calculation method f _n required calculation method in order to create a _{(x) f n1 (x)} , ···, obtains f _nM (x) are all In step S68, the calculation method f _n (x) is created based on the calculation methods f _n1 (x),..., F _nM (x) acquired and stored.

When the calculation method f _n (x) that needs to be acquired in stage n is acquired successfully, the host computer 10 in the third embodiment executes the processes of steps S69 and S70. Note that the processing in steps S69 and S70 is the same as the processing in steps S55 and S56 in the second embodiment, and a description thereof will be omitted. When step S70 is completed, the host computer 10 in the third embodiment executes the same processing as steps S21 to S29 in the first embodiment.

  As described above, also in the third embodiment, the same effect as that of the above embodiment can be obtained.

In addition, since the selected calculation method is read from the calculation method information 330 in a plurality of times, even one calculation method f _n (x) cannot be acquired unless all of the multiple readings are successful. This improves the security level.

In the above embodiment, the example in which all the calculation methods f _n (x) are divided into M pieces has been described, but the number of divisions may be different for each calculation method f _n (x).

<4. Modification>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made.

  For example, in the above embodiment, in the memory system 1, the ROM 2 that stores the information to be protected and the memory system 3 that stores the essential information 340 constitute an integral structure. However, for example, a storage medium corresponding to the memory array 21 of the ROM 2 is constituted by a CD-ROM, a controller 20 of the ROM 2 is constituted by a CD-ROM drive device provided in the host computer 10 and the CPU 11, and a removable storage medium. It is also possible to configure by mounting only the configuration corresponding to the memory system 3.

  Moreover, each process shown to the said embodiment is an illustration to the last, and if the same effect is acquired, the processing content in each process and the execution order of each process may be changed suitably.

1 Memory system 10 Host computer 2 ROM
20, 30 Controller 21, 31 Memory array 22 Unique key storage area 23 Program storage area 24 Content storage area 25 Key information 26 Program 3 Memory system 32 Data save area 320 Saved data 33 Calculation method storage area 330 Calculation method information 34 Essential information Storage area 340 Essential information 35 First table storage area 350, 351 First table 36 Second table storage area 360, 361 Second table 37 Progress history storage area 370 Progress history information 38 Output history storage area 380 Output history information

Claims (15)

A memory system connected to a host computer,
A first nonvolatile memory for storing information to be protected;
A first controller for controlling access to the first nonvolatile memory;
A second rewritable nonvolatile memory for storing in association with one-to-one more essential information and a plurality of operation result and the necessary when the host computer uses the information in the protected,
A second controller for controlling access to the second nonvolatile memory;
With
The memory system stores calculation method information defining a plurality of calculation methods, selects one calculation method from the plurality of calculation methods, and outputs the selected calculation method to the host computer as a selected calculation method.
The second controller selects one indispensable information from a plurality of indispensable information stored in the second non-volatile memory according to an output condition reflecting the state of the host computer, and is selected and indispensable. Output to the host computer as information ,
The output condition includes a condition based on a calculation result obtained by calculating calculation target information by the selected calculation method . The memory system of claim 1,
The memory information is information that reflects the state of the host computer . The memory system according to claim 1 or 2,
In the protection target information, the progress of the protection target information when executed by the host computer is defined as a plurality of stages,
The state of the host computer includes a state of the host computer when the host computer is executing any one of the plurality of stages . The memory system according to any one of claims 1 to 3 ,
The memory system selects one calculation method as the selected calculation method from the plurality of calculation methods according to the state of the host computer when a request is made from the host computer . A memory system according to any one of claims 1 to 4 ,
The selected computation method is a memory system that is selected according to the progress status of the information to be protected in the host computer . 6. The memory system according to claim 5 , wherein
When the progress status of the information to be protected in the host computer is notified, the second controller stores the notified progress status as progress history information in the second nonvolatile memory, and the progress history information A memory system for selecting the selected calculation method according to the method . The memory system according to any one of claims 1 to 6 ,
The output condition is a memory system including an output order when the second controller outputs the plurality of essential information. The memory system of claim 7 ,
A memory system in which the output order follows the order of progress of the information to be protected in the host computer . The memory system according to claim 7 or 8 ,
The memory system , wherein the second controller selects essential information to be output next time so as to be in the output order according to output history information when the essential information is output to the host computer . A memory system according to any one of claims 1 to 9 ,
The selected calculation method is a memory system that is read out in a plurality of times from the calculation method information . A memory system according to any one of claims 1 to 10 ,
The memory system in which the calculation method information is stored in the second nonvolatile memory. A memory system connected to a host computer ,
A plurality of indispensable information required when the host computer uses information to be protected and a plurality of calculation results are stored in a one-to-one relationship, and calculation method information defining a plurality of calculation methods is stored. Rewritable nonvolatile memory,
While controlling access to the non-volatile memory, one calculation method is selected from the plurality of calculation methods and output to the host computer as a selected calculation method, according to an output condition reflecting the state of the host computer A controller that selects one essential information from a plurality of essential information stored in the nonvolatile memory and outputs the selected essential information to the host computer as selected essential information;
With
The output condition includes a condition based on a calculation result obtained by calculating calculation target information by the selected calculation method . The memory system according to claim 12 , wherein
In the protection target information, the progress of the protection target information when executed by the host computer is defined as a plurality of stages,
The state of the host computer includes a state of the host computer when the host computer is executing any one of the plurality of stages . An information protection method for protecting protection target information stored in a first nonvolatile memory of a memory system connected to a host computer,
A rewritable second nonvolatile memory, and storing in association with the plurality of operation results and a plurality of essential information required when the host computer uses the information in the protected one to one,
Storing calculation method information defining a plurality of calculation methods;
Selecting one calculation method from the plurality of calculation methods and outputting it to the host computer as a selected calculation method;
In accordance with the output condition which reflects the state of the host computer including a computation result obtained by calculating the operand information by the object selection operation method, a plurality of essential information stored in the second nonvolatile memory Selecting one essential information and outputting it to the host computer as selected essential information;
An information protection method comprising: The information protection method according to claim 14,
In the protection target information, the progress of the protection target information when executed by the host computer is defined as a plurality of stages,
The state of the host computer includes the state of the host computer when the host computer is executing any one of the plurality of stages.

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