JP4080079B2 - IC card - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an IC card, and more particularly, to an IC card that has a CPU and a memory and performs various processes by causing the CPU to execute an application program stored in the memory.
[0002]
[Prior art]
Instead of magnetic cards that have been used as cash cards and credit cards, optical cards and IC cards have begun to spread. In particular, an IC card with a built-in CPU has an advantage that it can be used for expensive commercial transactions because it can ensure a high level of security.
[0003]
Currently, an IC card having a CPU that is generally used incorporates ROM, EEPROM, and RAM as memories. Usually, a basic program to be executed by the CPU is stored in the ROM, user data and various application programs are stored in the EEPROM, and the RAM is used as a work area of the CPU. Since the EEPROM is a rewritable memory, necessary data and application programs can be stored for each user.
[0004]
When data or programs are written to or read from an IC card, an external device called a so-called reader / writer device is used. Between the external device and the IC card, data and programs are transmitted to each other via a physical transmission line or a non-contact transmission path. Normally, information transmission from an external device to the IC card is given in the form of a command, and various instructions and data are transmitted to the IC card as one piece of information in the command. On the other hand, information transmission from the IC card to the external device is given in the form of a response, and the processing result and data are transmitted to the external device as one piece of information in the response.
[0005]
[Problems to be solved by the invention]
As described above, when using an IC card for general commercial transactions, ensuring security is an important issue. In a general IC card with a built-in CPU, when a memory in the IC card is accessed from an external device, the access to the memory via the built-in CPU is always used, so that the security related to data access can be considerably increased. it can. Therefore, normally, when accessing the IC card from an external device, settings such as various passwords are set as a condition, and if the verification fails, access is denied by the built-in CPU. In addition, when information is transmitted between an external device and an IC card, means for encrypting transmission information is also taken in order to ensure security on the signal transmission path.
[0006]
However, these security measures are measures for ensuring security when accessing the IC card from the outside by software, and are not measures related to the hardware security of the IC card itself. Until now, the general idea was that the IC card itself had sufficient security in terms of hardware. This is an idea from the viewpoint that it is almost impossible to read information in the IC card to the outside by hardware. However, when IC cards are used for high-priced business transactions, it is necessary to make every effort to ensure hardware security. For example, if the IC card is physically disassembled, the built-in memory is mechanically cut, and the cut surface is analyzed, it is not impossible to recognize the bit pattern in the memory. Therefore, in the case of an IC card used for expensive commercial transactions, it cannot always be said that the conventional security measures alone are perfect.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide an IC card that can ensure more complete security.
[0008]
[Means for Solving the Problems]
(1) A first aspect of the present invention is an IC card that includes a CPU and a memory, and performs various processes by causing the CPU to execute an application program stored in the memory.
An encryption program storage unit for storing an application program encrypted based on a predetermined encryption procedure;
A decryption procedure storage unit for storing a decryption procedure corresponding to the encryption procedure;
A decryption program storage for storing the application program decrypted by the decryption procedure;
On the memory,
Until the execution instruction regarding the application program is given from the external device, the application program is stored in the encrypted program storage unit in an encrypted state,
When an execution instruction is given, decryption is performed based on the stored decryption procedure, the decrypted application program is stored in the decryption program storage unit, and the decrypted application program is executed. Thereafter, a process of deleting the decrypted application program from the decrypted program storage unit is performed.
[0009]
(2) According to a second aspect of the present invention, in the IC card according to the first aspect described above,
The application program is stored in the encrypted program storage unit with only a part of the application program encrypted.
[0010]
(3) According to a third aspect of the present invention, in the IC card according to the first aspect described above,
The application program is divided into a plurality of blocks, each block is encrypted based on a plurality of different encryption procedures, and each encrypted block is stored in the encryption program storage unit.
The decryption procedure corresponding to each of the plurality of encryption procedures is stored in the decryption procedure storage unit,
When the application program is decrypted, decryption is performed using a decryption procedure corresponding to each block.
[0011]
(4) A fourth aspect of the present invention is the IC card according to the first to third aspects described above,
Multiple application programs are encrypted and stored in the encrypted program storage unit,
When an instruction to select a specific application program is given from an external device, the selected application program is decrypted.
[0012]
(5) According to a fifth aspect of the present invention, in the IC card according to the fourth aspect described above,
When the execution of the selected application program is completed, a process for deleting the decryption program for the selected application program stored in the decryption program storage unit is performed.
[0013]
(6) According to a sixth aspect of the present invention, in the IC card according to the first to third aspects described above,
When a specific command for a specific application program is given from an external device, at least a part of the specific application program necessary for execution of the given specific command is decrypted It is.
[0014]
(7) According to a seventh aspect of the present invention, in the IC card according to the sixth aspect described above,
Every time the execution of a specific command given from an external device is completed, a process of deleting the decryption program stored in the decryption program storage unit is performed.
[0015]
(8) The eighth aspect of the present invention is the IC card according to the first to seventh aspects described above,
As a decryption procedure, a decryption procedure using a key given from the outside is used.
[0016]
(9) A ninth aspect of the present invention is the IC card according to the first to eighth aspects described above,
The decryption program storage unit is provided in a volatile memory whose stored contents are lost when the power is turned off.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a block diagram showing a state in which information is transmitted between a general IC card 10 and an external device (reader / writer device) 20. In this example, the IC card 10 includes a CPU 11 having various arithmetic processing functions, an I / O interface 12 for transmitting / receiving information to / from the external device 20, and memories such as a ROM 13, an EEPROM 14, and a RAM 15. The ROM 13 is a non-rewritable nonvolatile memory, and the CPU 11 executes predetermined processing based on a basic program stored in the ROM 13. The EEPROM 14 is a rewritable nonvolatile memory and stores user data and various application programs. The RAM 15 is a rewritable volatile memory used as a work area when the CPU 11 executes various processes.
[0018]
The IC card 10 and the external device 20 are connected to each other by a method such as a connection using a physical signal line, a connection using infrared rays, or a non-contact connection using electromagnetics, and information is transmitted and received. Information is transmitted from the external device 20 to the IC card 10 in the form of a command. The transmitted command is given to the CPU 11 via the I / O interface 12. Conversely, information is transmitted from the IC card 10 to the external device 20 in the form of a response to a given command. This response is transmitted from the CPU 11 to the external device 20 via the I / O interface 12. As already described, various techniques have been proposed for security measures when accessing the IC card 10 from the external device 20 by software. As shown in the figure, access to all memories is performed via the CPU 11, and direct access to the memory in the IC card 10 from the external device 20 cannot be performed.
[0019]
However, it is possible to access each memory in the IC card 10 by hardware. Since power supply to the IC card 10 is normally performed from the external device 20 side, when the connection between the IC card 10 and the external device 20 is released, the power supply to the IC card 10 is cut off. As a result, data in the RAM 15 which is a volatile memory is lost. However, since the ROM 13 and the EEPROM 14 are non-volatile memories in which the stored contents are preserved even after the power supply is cut off, the stored contents may be read out by hardware access. For example, it is not impossible to extract the stored bit pattern by physically disassembling the IC card 10 obtained by unauthorized means, slicing the built-in ROM 13, and observing the cross section thereof. . Also, with respect to the EEPROM 14, it is not impossible to extract the stored bit pattern if the capacitance of each part is measured finely.
[0020]
When memory contents are read by such illegal means, a particularly serious problem is that the built-in application program is analyzed. Of course, when user data is read and analyzed, problems will arise, but user data is information related to one person, whereas application programs are commonly used in many IC cards. If the contents are analyzed, software fraud is promoted this time.
[0021]
The main point of the present invention is to prevent an application program stored in the ROM 13 or the EEPROM 14 from being analyzed by such a hardware fraud. Therefore, the IC card according to the present invention has the following three features.
(1) The application program is stored in the ROM 13 or the EEPROM 14 in an encrypted state.
(2) A procedure for decrypting the encrypted application program is stored in the ROM 13 or the EEPROM 14, and this is decrypted and used in the IC card when the application is executed.
(3) After the application execution is completed, the decrypted application program is deleted.
[0022]
With these three features, it is possible to prevent a situation in which an application program inside the IC card is analyzed by unauthorized means. That is, because of the feature (1), the application program in the ROM 13 or the EEPROM 14 is stored in an encrypted state. Therefore, even if a bit pattern is read out in hardware by an illegal act, the application program is immediately analyzed. I can't do it. Further, according to the feature (2), when it is necessary to execute the application program as a legitimate action, the decryption is performed inside the IC card, and the application program is executed in the decrypted state. As long as it is used, there will be no trouble. Furthermore, because of the feature (3), when the execution of the application is completed, the decryption application program used for the execution is erased, so even if the bit pattern is read out by hardware, the application immediately The program cannot be analyzed.
[0023]
In practice, one application program is divided into a plurality of blocks, each block is encrypted based on a plurality of different encryption procedures, and each encrypted block is stored in the ROM 13 or the EEPROM 14. preferable. According to such a method, although the same application program is used, a different encryption procedure is used for each part. Therefore, even if a bit pattern is read by unauthorized means, This is because it becomes more difficult to infer the conversion procedure, and the analysis of the application program can be made more difficult. Of course, when encryption is performed using different encryption procedures for each block in this way, it is necessary to prepare a decryption procedure corresponding to each of the plurality of encryption procedures in the IC card, and decryption of the application program When performing the conversion, it is necessary to perform decoding using a decoding procedure corresponding to each block.
[0024]
FIG. 2 is a conceptual diagram showing such an encryption method for each block. Actually, this encryption procedure is performed outside the IC card 10. Here, a method of encrypting one application program 30 is shown. First, the application program 30 is divided into a plurality of blocks. In the example shown in the figure, the first block 31 and the second block 32 are divided into two blocks, but of course, the blocks may be divided into three or more blocks. Thus, when the division for each block is completed, encryption is performed for each individual block. At this time, different encryption procedures are used for each block. In the illustrated example, the first block 31 is encrypted based on the encryption procedure A to obtain the first encrypted block 41, and the second block 32 is encrypted. The encryption based on the procedure B is performed, and the second encryption block 42 is obtained.
[0025]
In the embodiment shown here, encryption procedure information and length information are added to each encryption block. The encryption procedure information is information indicating which encryption procedure is used for encryption, and the length information is information indicating the length (for example, the number of bytes) of the encryption block. In the illustrated example, the first encryption block 41 includes encryption procedure information Ra (information indicating that encryption based on the encryption procedure A has been performed) and length information L11 (first encryption block). The first registration encryption block 51 is formed by adding the encryption procedure information Rb (encryption procedure B) to the second encryption block 42. And the length information L12 (information indicating the length of the second encryption block 42) and the second registration encryption block 52 by adding the length information L12 (information indicating the length of the second encryption block 42). Is forming. The encryption procedure information Ra and Rb added here is used to select which decryption procedure should be used for decryption when decrypting later.
[0026]
When the first and second registration encryption blocks 51 and 52 are created in this way, processing for transmitting them from the external device 20 to the IC card 10 and registering them in the EEPROM 14 in the IC card 10 is performed. The above is a procedure for registering one application program 30 in the EEPROM 14, but in this embodiment, a case will be considered in which a plurality of application programs are registered in the EEPROM 14 in the same procedure.
[0027]
FIG. 3 is a block diagram showing an information storage state in the memory in the IC card according to the embodiment of the present invention. As described above, the IC card includes the ROM 13, the EEPROM 14, and the RAM 15, and all the memories are accessed by the built-in CPU 11.
[0028]
In the example shown here, the EEPROM 14 functions as an encryption program storage unit for storing an application program encrypted based on the above-described encryption procedure. In the figure, a state in which the encrypted first application program and second application program are stored in the EEPROM 14 is shown. The first application program is composed of first and second registration encryption blocks 51 and 52 shown in FIG. 2, and the second application program is similar to the first and second encryption blocks. It consists of registration encryption blocks 61 and 62. Here, Ra, Rb, and Rc are encryption procedure information indicating which encryption procedure is performed based on the encryption procedure, and indicate that encryption based on the encryption procedures A, B, and C is performed. Show. L11, L12, L21, and L22 are length information indicating the length of each encrypted block.
[0029]
In addition, the ROM 13 functions as a decryption procedure storage unit for storing a decryption procedure corresponding to each encryption procedure. The figure shows a state in which three types of decryption procedures AA, BB, and CC are stored. These decryption procedures are decryption procedures corresponding to the encryption procedures A, B, and C, respectively. ing. For example, a block encrypted based on the encryption procedure A can be decrypted by the decryption procedure AA. Therefore, in the case of the illustrated example, the blocks 51, 52, 61, 62 registered in the EEPROM 14 can be decrypted based on any decryption procedure prepared in the ROM 13. In other words, the application program registered in the EEPROM 14 needs to be encrypted by an encryption procedure corresponding to one of the decryption procedures prepared in the ROM 13.
[0030]
On the other hand, the RAM 15 functions as a decryption program storage unit for storing the application program decrypted by the decryption procedure prepared in the ROM 13. That is, when the CPU 11 performs decoding on the block in the EEPROM 14, the CPU 11 performs processing for sequentially expanding the decoded code in the RAM 15. In the illustrated example, a state where the decrypted first application program is expanded in the RAM 15 is shown. The decrypted program is composed of a first block 31 and a second block 32. These blocks 31 and 32 are blocks constituting the application program 30 shown in FIG.
[0031]
FIG. 3 shows a state in which the decrypted first application program is stored in the RAM 15, but actually, until an execution instruction regarding the first application program is given from the external device 20. The first application program is stored in the EEPROM 14 (encrypted program storage unit) in an encrypted state. Of course, the CPU 11 cannot execute the encrypted application program as it is. Therefore, when it becomes necessary to execute a specific application, the CPU 11 executes a process of decrypting the specific application in the EEPROM 14 and developing it in the RAM 15. For example, when it becomes necessary to execute the first application program, the CPU 11 performs a decryption process on the first registration encryption block 51 and the second registration encryption block 52 in the EEPROM 14. A process of expanding the result in the RAM 15 is performed. For example, when decrypting the first registration encryption block 51, the encryption procedure information Ra recognizes that this block has been encrypted based on the encryption procedure A, and corresponds to this. Decoding processing is performed using the decoding procedure AA (prepared in the ROM 13). FIG. 3 shows a state after such a decoding process is performed. The CPU 11 executes this using the first application program (in a decrypted state) obtained on the RAM 15 in this way.
[0032]
Thus, when the execution of the first application program is completed, the CPU 11 erases the first application program (that is, the first block 31 and the second block 32) expanded in the RAM 15 (for example, 00 Process to overwrite any data such as). Eventually, the first application program stayed in the RAM 15 in the decrypted state only for the period required for execution. After the completion of the execution, the first application program is in the IC card 10 in the decrypted state. One application program does not exist. Therefore, the possibility that an application program in a decrypted state is read out to the outside due to unauthorized hardware access is extremely low.
[0033]
In the example shown in FIG. 3, the decoding procedure is stored in the ROM 13, but the decoding procedure may be stored in the EEPROM 14. In this case, the necessary decryption procedure can be written into the EEPROM 14 each time and used. In the example shown in FIG. 3, the encrypted application program is written and used in the EEPROM 14. However, the encrypted application program may be prepared in the ROM 13 in advance. Further, in the example shown in FIG. 3, the RAM 15 is used as a memory for developing the decrypted application program. However, the decrypted application program may be expanded on the EEPROM 14. However, in practice, it is preferable to use the RAM 15 as a decryption program storage unit. The reason is that the EEPROM 14 is a non-volatile memory whose stored contents are retained even after the power is shut off, while the RAM 15 is a volatile memory whose stored contents are lost when the power is shut off. For example, if an unauthorized person performs an act of forcibly disconnecting the both while the IC card 10 is connected to the external device 20 and performing any operation, the data in the RAM 15 Is lost, but the data in the EEPROM 14 remains as it is. Therefore, when the EEPROM 14 is used as the decryption program storage unit, there is a risk that the decrypted application program remains in the EEPROM 14 without being erased.
[0034]
FIG. 4 is a flowchart showing an example of a processing procedure performed in the IC card 10 according to the present invention. Such a processing procedure itself is prepared in advance in the ROM 13 and is executed by the CPU 11. First, in step S1, command reception is performed. As described above, all instructions from the external device 20 to the IC card 10 are given in the form of commands. Therefore, first, a command given from the external device 20 side is received via the I / O interface. In this embodiment, the commands given in this way are divided into three types. That is, there are three types: an application selection command, an application end command, and a general command. The application selection command is a command for giving an instruction to select a specific one of a plurality of application programs (all stored in an encrypted state) registered in the EEPROM 14 as an execution target. The application end command is a command for giving an instruction to end the execution of the currently selected application program. Actually, when a command for selecting a new application is given in a state where an application has already been selected, the new application is selected and the selection of the old application is canceled and the process ends. Therefore, such a command is a command that serves as both an application selection command and an application end command. Here, for convenience of explanation, an example in which both commands are given as separate commands is shown. . The general commands are various commands for the currently selected application program, and the contents thereof are determined by each application program.
[0035]
In order to cause the IC card 10 to execute a predetermined application program, it is usually sufficient to transmit a command in the following procedure from the external device 20 side. First, an application selection command is transmitted to select a specific application program. Subsequently, various general commands corresponding to the selected application program are sequentially transmitted, and a desired process is performed by the selected application program. Finally, an application termination command is transmitted, and the selection of the currently executing application program is canceled (in fact, as described above, the command for selecting a new application is a command that also serves as the termination command for the old application. Often used). Let's look at the flowchart of FIG. 4 on the premise that commands are given from the external device 20 to the IC card 10 in the above order.
[0036]
First, in step S2, it is determined whether the command received in step S1 is an application selection command, and in step S3, it is determined whether it is an application end command. If it is neither of them, it is determined as a general command (command for a specific application program), and it is determined in step S4 whether or not an application has been selected. If the application has not been selected, an error is set in step S5, and the set error is transmitted to the external apparatus 20 as a response in step S6. This error means that a command for a specific application program is given in a state where the application program is not selected.
[0037]
If the received command is an application selection command, the process proceeds from step S2 to step S7, and an application selection process is performed. That is, one of the application programs is selected (specifically, for example, a flag indicating the selected application program is recorded on the RAM 15). Subsequently, in step S8, the selected application program is decrypted. The decrypted application program is expanded in the RAM 15, and a response indicating that the application selection procedure is completed is transmitted in step S6.
[0038]
On the other hand, if the received command is an application termination command, the process proceeds from step S3 to step S9 (if the command for selecting a new application also serves as the termination command for the old application, the process proceeds from step S8 to step S9. The selection cancellation processing of the currently selected application program is performed (specifically, for example, the flag on the RAM 15 indicating the selected application program is deleted). Subsequently, in step S10, the completed application program is deleted. That is, the decrypted application program developed in the RAM 15 is deleted. In step S6, a response indicating that the application termination procedure has been completed is transmitted.
[0039]
If the received command is a general command and one of the application programs has been selected at that time, the process proceeds from step S4 to step S11, and the given general command has been selected. It is determined whether the command corresponds to the application program. If it is not a corresponding command, an error is set in step S5, and this error is transmitted as a response in step S6. If the command is a corresponding command, the process proceeds to step S12, and the given command is executed by the decrypted application program (currently selected application program) developed in the RAM 15, and the result is In step S6, it is transmitted as a response.
[0040]
After all, according to the procedure shown in the flowchart of FIG. 4, when an instruction to select a specific application program is given from the external device 20, the selected application program is decrypted and expanded in the RAM 15. When the execution of the selected application program is completed, the decryption program stored in the RAM 15 is deleted. During execution of the selected application program, the general command is executed by the decrypted application program developed in the RAM 15.
[0041]
By the way, in the procedure shown in FIG. 4, the entire application program is decrypted at a selected stage, and the entire decrypted program is erased after waiting for the end of the application program. It is not always necessary to take the procedure of decoding the whole and erasing the whole, but it is possible to take the procedure of decoding every part and erasing every part. For example, when a specific command for a specific application program is given from the external device 20, at least a part necessary for execution of the given specific command is decrypted in the specific application program. The decrypted program may be deleted each time execution of this specific command is completed. Normally, many commands are defined in the application program, and only a part of the routines in the application program is used to execute each command. Therefore, if a method of decoding and using only a part of a routine necessary for execution of a given command is unnecessary, there is no need to perform unnecessary decoding processing. Further, since the decryption program expanded in the RAM 15 is only a part of the routine necessary for execution, it is possible to further reduce the possibility that the entire application program is read out.
[0042]
As mentioned above, although this invention was described based on embodiment shown in figure, this invention is not limited to these embodiment, In addition to this, it can implement in a various aspect. For example, in the above-described embodiment, the entire application program is encrypted and registered in the IC card. However, the encryption of the application program is not necessarily performed on the whole, and is particularly necessary for security. Only a part may be encrypted, and the remaining part may be registered in the IC card without being encrypted.
[0043]
In order to implement the present invention, it is necessary to prepare a decryption procedure in the IC card. However, there is a possibility that the decryption procedure is read out by an unauthorized means. Therefore, in order to further improve the security, it is preferable to adopt a method that uses a predetermined key for encryption and decryption. In this case, in order to execute the decryption procedure, it is necessary to give a key to the IC card from the outside. Therefore, even if the decryption procedure inside the IC card is read by an unauthorized means, Since decoding cannot be performed immediately using the decoding procedure, security is improved. The key necessary for decryption may be given to the IC card 10 from the external device 20 side, for example, together with the application selection command.
[0044]
【The invention's effect】
As described above, according to the IC card of the present invention, the application program is stored in the IC card in an encrypted state, and is decrypted and used only when necessary, and the decrypted program is erased after use. As a result, it becomes possible to ensure more complete security.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a state in which information is transmitted between a general IC card 10 and an external device (reader / writer device) 20. FIG.
FIG. 2 is a conceptual diagram showing a block-by-block encryption method used in the present invention.
FIG. 3 is a block diagram showing an information storage state in a memory in the IC card according to the embodiment of the present invention.
FIG. 4 is a flowchart showing an example of a processing procedure performed by the IC card according to the present invention.
[Explanation of symbols]
10 ... IC card
11 ... CPU
12 ... I / O interface
13 ... ROM
14… EEPROM
15 ... RAM
20 ... External device
30 ... Application program
31 ... first block
32 ... the second block
41. First encryption block
42. Second encryption block
51... First registration encryption block
52 ... Second registration encryption block
61. First registration encryption block
62 ... Second registration encryption block
A, B ... Encryption procedure
AA, BB, CC ... Decoding procedure
L11, L12, L21, L22 ... block length information
Ra, Rb, Rc ... Block encryption procedure information

Claims (9)

In an IC card that has a CPU and a memory and performs various processes by causing the CPU to execute application programs stored in the memory,
An encryption program storage unit for storing an application program encrypted based on a predetermined encryption procedure;
A decryption procedure storage unit for storing a decryption procedure corresponding to the encryption procedure;
A decryption program storage for storing the application program decrypted by the decryption procedure;
On the memory,
Until the execution instruction related to the application program is given from an external device, the application program is stored in the encrypted program storage unit in an encrypted state,
When the execution instruction is given, the decryption is performed based on the decryption procedure, the decrypted application program is stored in the decryption program storage unit, and the decrypted application program is executed. An IC card having a function of performing a process of erasing the decrypted application program from the decrypted program storage unit. In the IC card according to claim 1,
An IC card, wherein an application program is stored in an encrypted program storage unit in a state where only a part thereof is encrypted. In the IC card according to claim 1,
The application program is divided into a plurality of blocks, each block is encrypted based on a plurality of different encryption procedures, and each encrypted block is stored in the encryption program storage unit.
A decryption procedure corresponding to each of the plurality of encryption procedures is stored in a decryption procedure storage unit,
An IC card characterized in that when an application program is decrypted, decryption is performed using a decryption procedure corresponding to each block. In the IC card according to any one of claims 1 to 3,
Multiple application programs are encrypted and stored in the encrypted program storage unit,
An IC card characterized in that, when an instruction to select a specific application program is given from an external device, the selected application program is decrypted. In the IC card according to claim 4,
An IC card that performs a process of erasing a decryption program for the selected application program stored in a decryption program storage unit when execution of the selected application program is completed. In the IC card according to any one of claims 1 to 3,
When a specific command for a specific application program is given from an external device, at least a part necessary for execution of the specific command in the specific application program is decrypted. IC card. In the IC card according to claim 6,
An IC card that performs a process of erasing a decryption program stored in a decryption program storage unit every time execution of a specific command given from an external device is completed. In the IC card according to any one of claims 1 to 7,
An IC card characterized in that a decryption procedure using a key given from the outside is used as a decryption procedure. In the IC card according to any one of claims 1 to 8,
An IC card, wherein a decryption program storage unit is provided in a volatile memory in which stored contents are lost when the power is turned off.

Images