JPH04232588A - Data ciphering system using ic card - Google Patents

Abstract

PURPOSE:To keep a high security by building a ciphering means, which is stored in a storage device, in an IC card at the time of IC card production or updating the ciphering means with a new means sent from an external host device at the time of the use. CONSTITUTION:An IC card 10 incorporating an IC chip 13 is used, and with respect to this IC chip 13, ciphering soft and a ciphering key as the ciphering means which ciphers data are stored in the storage device like an EEPR0M 17 which is electronically rewritable and whose contents cannot be decoded by a microscope.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encryption system for transmitting and receiving data between a host device and an IC card while maintaining security.

0002

[Prior Art] Conventionally, in order to protect the security of data sent and received between an IC card and a host device, it has been possible to encrypt the data before transmitting it, decrypt the received encrypted data, and reproduce the data. It is done. This encryption is performed using encryption software stored in a ROM or the like.

0003

[Problem to be solved by the invention] Conventional encryption software is a program fixedly installed in ROM etc., so it can be decrypted using an electron microscope etc. It is difficult to maintain the security of transmitted data.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention includes a CPU, a storage means used in connection with the CPU and including a storage device whose storage contents can be electronically rewritten, and an IC card having means for inputting and outputting data under the control of a CPU; the storage device stores an encryption means for encrypting the data; and the storage device stores an encryption means for encrypting the data; The present invention provides a data encryption system using an IC card, which is characterized in that the data is encrypted using the encryption means that is used in the present invention.

[0005]

[Operation] Electronically rewritable storage devices are, for example, EE.
This is a PROM, and since storage is performed depending on whether or not charge is injected into the memory cell, the stored contents cannot be deciphered even if the internal structure is examined using an electron microscope or the like. Therefore, if data is encrypted using encryption software and an encryption key as an encryption means stored in such a storage device, the encrypted data transmitted between the IC card and the host device will be protected. Security can be safely ensured.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, FIG. 1 shows a block diagram of the internal structure of a data communication system and an IC card configured using a one-chip IC. In the figure, an IC card 10 is connected to a connection terminal 1 that is connected to the communication IC card terminal 1 when the IC card 10 is inserted into the communication IC card terminal 1 shown in the figure.
1. This connection terminal 11 is inside the IC card 10.
An IC chip 13 is provided which is connected to the outside via. The IC chip 13 includes a CPU 14, a ROM 15, and a RAM.
16, EEPROM 17, etc. The communication terminal 1 performs data communication with a host device 3 via a communication satellite 2, for example.

FIG. 2 shows the memory configuration of the ROM 15 and EEPROM 17 in the IC chip 13, and the ROM 15 contains a C for basic control of the IC card 10.
A basic program for the PU 14, communication control software for exchanging data with the outside, application software, etc. are stored.

[0008] Encryption software and an encryption key are stored in the EEPROM 17.

The operation of storing encryption software and an encryption key in the IC card 10 according to the embodiment of the present invention at the manufacturing stage will be described below with reference to the flowchart shown in FIG. For example, an IC card 10 manufactured in a factory
is inserted into a manufacturer's terminal (not shown) with neither encryption software nor encryption key stored in the EEPROM 17. In the figure, in the first step ST1, the inserted I
It is checked whether encryption software is stored in the C card 10 or not. This check is performed by checking whether a flag is set in the RAM 16, for example. If the flag is set, it is determined that the encrypted software has already been stored, and the answer is NO, and the process proceeds to step ST2, where normal processing is performed.

[0010] In this case, the answer is YES, so step ST
Proceed to step 3, and the manufacturer's identification number (PIN) is sent from the terminal to the IC.
sent to card 10. A PIN identical to this PIN is previously stored in the RAM 16 of the IC card 10 at the time of manufacture, and the CPU 14 reads this PIN from the RAM 16 and compares it with the input PIN in step 4. As a result of the comparison, if there is no match, the answer is NO and the process ends.

[0011] When both PINs match, the CPU 14 outputs a transmission request to the terminal, and the terminal sends the IC card 10
In the next step ST5, the encryption software is sent to. This encryption software uses EEP by specifying the address of CPU14.
The data is stored in the ROM 17. All encryption software is EE
When stored in the PROM 17, the result of step ST6 is Y.
ES, and the storage process of the encrypted software ends.

[0012] Once the encryption software is stored in the EEPROM 17, processing for storing the encryption key in the EEPROM 17 is then performed. Since this operation can be performed in the same manner as the storage of the encrypted software shown in FIG. 3, detailed explanation will be omitted here.

The IC card 10 with the encryption software and encryption key stored in the EEPROM 17 in this way is delivered to the user via the card issuer, but at this time, the user's PIN is stored in the EEPROM 17 as necessary. You may also do this.

Next, the case of transmitting and receiving data to and from a host device using the IC card 10 handed to the user will be explained with reference to the flowchart shown in FIG. IC
When the IC card 10 is inserted into the external card terminal and the power of the terminal is turned on, the ROM 15 in the IC card 10
The programs stored therein are activated, and an initial sequence is executed in step ST11. When this initial sequence is completed, the process proceeds to the next step ST12, and the IC
Various information is exchanged between the card 10 and the external terminal.

[0015] When this information exchange is completed, the process moves to the next step ST13, where the application software is started, and then moves to the next step ST14, where the encryption software is started. The above processing is performed by software stored in the ROM 15.

[0016] When the encryption software is started, the CPU 14
The EEPROM 17 is accessed by
The encrypted software is read out at T15. Following reading of the encryption software, in the next step ST16, the EEPRO
The encryption key is also read from M17. When a data transmission request is requested from an external host device in this state, the CPU
For example, the user PIN is read out from the RAM 16 in step ST14, and in step ST17, the PIN is encrypted using the encryption key according to the encryption software, and is sent from the terminal to the host device.

When this is completed, the process proceeds to step ST18, where the application software is read out from the ROM 15 by the CPU 14 and executed. Following this, step ST19
Various information is exchanged with the external terminal, and the process ends.

As described above, since the encryption software and the encryption key are electronically stored in the EEPROM 17, there is no risk that the IC chip 13 will be decoded even when viewed under an electron microscope, and the security of the IC card 10 is improved. You will definitely be protected.

The encryption software stored in the EEPROM 17 in the above embodiment is stored at the time the IC card 10 is manufactured, and its contents are not changed at all thereafter. Therefore, even if it cannot be deciphered using an electron microscope, there remains a possibility that it will be deciphered by other methods after being used for a long time.

[0020] Therefore, the encryption software stored in the IC card is divided into two stages, one of which is a unique one that is built in when the IC card is manufactured as described above, and the other is a changeable one that is supplied from the host device. There are ways to further increase security.

FIG. 5 shows the memory configuration of an IC card incorporating this two-stage encryption software, and the ROM 15 stores basic control software, communication control software,
Contains application software. EEPROM17 is the first
It stores unique encryption software A and encryption key KA as an encryption means, and also stores variable encryption software B and encryption key KB as a second encryption means. Unique encryption software A and encryption key KA are stored in the EEPROM 17 when the IC card is manufactured, but variable encryption software B and encryption key KB are supplied from the host device to the IC card as appropriate during use. It is. For example, when an IC card is inserted into an external terminal, the variable encryption software and encryption key may be sent from the host device to the IC card prior to data transmission/reception.

[0022] Below, with reference to the flowchart of FIG. 6,
As shown in Figure 5, two-stage encryption software is installed on the EEPROM17.
The operation of data communication using an IC card stored in the following will be explained. In the figure, when the power is turned on with the IC card inserted into the external terminal, an initial sequence is executed in step ST21 according to the program read from the ROM 15. When this initial sequence is completed, the process proceeds to step ST22, where information is exchanged between the IC card and the external terminal.

[0023] When this information exchange is completed, the process moves to the next step ST23, where the application software is started, and then the process moves to the next step ST24, where the encryption software A is activated.
is started.

[0024] When the encryption software A is started, the EEPR
The encryption software A is read from the OM17 in step ST25, and then the encryption key KA is read out in the next step ST26.
is also read out. When a data transmission request is issued from the external host device in this state, for example, the PIN is read out, and in step ST27, the PIN is encrypted using the encryption key KA according to the encryption software.

[0025] Next, step ST starts from the EEPROM 17.
In step 28, the encryption software B is read out, and then in step ST
In step 29, the encryption key KB is read out. Using the read encryption key KB, the PIN is encrypted according to the encryption software B in step ST30.

The PIN encrypted using the encryption software A and B as described above is sent to the external host device. After this, the application software is executed in step ST31, and then information exchange with an external terminal is executed in step ST32. The process ends when the information exchange ends.

In this case, the variable encryption software B is updated with a new one from the external host device at an appropriate time, making it extremely difficult for a third party to decipher.

[0028] Since two types of encryption software and encryption keys are used, one piece of data is first encrypted using encryption key KA according to encryption software A, and then this encrypted data is further encrypted using another encryption key KB. Using encryption software B
It is also possible to double-encrypt the information by encrypting it according to the following.

[0029] Furthermore, in the above explanation, encrypted data using encryption software A and encryption key KA and encrypted data using encryption software B and encryption key KB are considered to have mutually related contents. By doing so, further improvement in security can be expected.

[0030]

As described above, according to the present invention, since the encryption means for encrypting data is stored in an electronically rewritable storage device such as an EEPROM, security is improved. An encryption system using an IC card with extremely high security can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is an internal layout diagram of the storage device in FIG. 1;

FIG. 3 is a process diagram of encrypted software storage during IC card manufacturing.

FIG. 4 is a flowchart of information exchange using this embodiment.

FIG. 5 is an internal layout diagram of a storage device according to another embodiment.

FIG. 6 is a flowchart of information exchange using the storage device of FIG. 5;

[Explanation of symbols]

1...Communication terminal, 2...Communication satellite, 3...Host device, 10...
IC card, 11... Connection terminal, 13... IC chip, 14
...CPU, 15...ROM, 16...RAM, 17...EEP
ROM.

Claims (2)

[Claims] 1. An IC comprising a CPU, a storage means that is used in conjunction with the CPU and includes at least a storage device whose storage contents can be electronically rewritten, and means for inputting and outputting data under the control of the CPU. a card, the storage device stores an encryption means for encrypting the data, and the data is encrypted using the encryption means stored in the storage device under the control of the CPU. A data encryption system using an IC card, which is characterized by: 2. An IC comprising a CPU, a storage means used in connection with the CPU and including at least a storage device whose storage contents can be electronically rewritten, and means for inputting and outputting data under the control of the CPU. a card, the storage means stores a first encryption means unique to the IC card for encrypting the data, and a second encryption means supplied from outside the IC card, Data encryption using an IC card, characterized in that the data is encrypted by selectively using the first encryption means and the second encryption means stored in the storage device under the control of system.