JP2001060256A - Ic card having data updating function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To omit a special card processing center that is necessary for updating a cipher key and to attain the safe updating of the key by registering the scheduled updating date of the key in a storage of an IC card and updating the key in the IC card after its scheduled updating date. SOLUTION: It is discriminated whether a key updating table is registered (S4). When the key updating table is registered, it is discriminated whether a 1st scheduled updating date of a cipher key has passed (S5). When the updating data has passed, it is discriminated whether a 1st cipher key is updated (S6). When the 1st key is not updated, the key is generated and updated (S7). When the 1st key is updated, it is discriminated whether another scheduled updating date of the cipher key is set (S8). When the scheduled updating date is set, it is discriminated whether the N-th scheduled updating date of the key has passed (S9). When the N-th scheduled updating date has passed, it is discriminated whether the N-th updating of the key is already carried out (S10). When the N-th updating of the key is not carried out, the key is generated and updated (S11). This operation is repeated until a new scheduled updating date of the key is not set any more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an IC card mainly used for credit cards and electronic money.

[0002]

2. Description of the Related Art An IC card used as a credit card, electronic money, or the like has a built-in arithmetic device, a ROM storing a control program, a RAM serving as a calculation work area, a non-volatile memory storing application programs, and data. It has a function of interpreting and executing a command transmitted from the reader / writer, updating the contents of the nonvolatile memory as necessary, and returning a processing result to the reader / writer as a response.

As shown in FIG. 1, a transaction using an IC card is performed by setting an IC card 1 in a terminal device 2 installed as a reader / writer installed in a store or the like and inputting a recitation number through the terminal device. A decision is taken, and in order to manage the risk of the card, necessary data is sent from the terminal device 2 to the host computer 3 of the card issuer such as a credit company through a dedicated line, and the system is checked online.

In such a transaction using an IC card, an IC card 1, a terminal device 2, a host computer 3
In order to ensure security, an encryption key is recorded at the time of IC card issuance processing, and data is encrypted and transmitted between the three parties in order to secure security. Also, if the same key is used, there is a risk that the key will be decrypted by a third party, so the key is updated from the host computer through a specific terminal device at a certain timing.

[0005]

However, in the conventional method, when the key update time comes, the key update is performed by performing a special process using a special terminal device at a special place (center). And a special card processing center was required, and the key updating work was complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has as its object to eliminate the need for a special card processing center for key update and to enable key update safely.

[0007]

According to a first aspect of the present invention, an encryption key is stored in an IC card having an arithmetic unit and a storage device, and data is encrypted between a terminal device and a host computer for transmission and reception. The system is characterized in that a scheduled update date of the encryption key is registered in the storage device of the IC card, and the encryption key is updated in the IC card after the scheduled update date. With IC card. The invention according to claim 2 is characterized in that the IC card generates and updates a new key by calculating from the current encryption key data and transaction count data.
The invention according to claim 3 is characterized in that the IC card determines the update time based on external time information and the scheduled update date. The invention according to claim 4 is characterized in that an encryption key calculated by a host computer from data relating to an IC card and a master key is set as an initial encryption key of the IC card.

[0008]

Embodiments of the present invention will be described below. The IC card of the present invention is used in a system for exchanging data with the host computer and the terminal device shown in FIG.

FIG. 2 is a diagram showing secret key data stored during IC card issuance processing according to the present invention. Data to be updated in the IC card is stored in a data encryption DES (Da
ta Encryption Standard) In the case of a secret key, the DES secret key is held in the IC card and the host computer.
The DES secret key is a block cipher that has been widely introduced commercially in symmetric cryptosystems that use the same key for encryption and decryption. The tag C1 is a name indicating a secret key, and stores a data length and a key value in hexadecimal.

FIG. 3 is a view showing a scheduled update date table showing the key update timing registered in the IC card.
It is shown in a CD (Binary Decimal) format, and stores an update schedule (in this example, December 1, 1999, December 1, 2000) together with the data name and data length. . The host computer also has the same information and notifies the IC card of the key update based on the schedule.

Since the IC card itself does not have a clock, as shown in FIG. 4, the update time is determined from the clock data (date information) from the host computer and the scheduled update date data held by the IC card. Perform key update processing.

As shown in FIG. 5, as the data used for the key update processing, the host computer holds a master key for key generation. On the IC card side, an ATC (Application Transactio) which is a counter for counting the number of transactions with the current key before the update and the IC card.
n Counter), IC card serial number, P
AN (Primary Account Number), same P
There are different cards in AN, so P to distinguish them
Stores the AN sequence number. When generating the key, the host computer sends the card serial number, PAN, PAN sequence number, AT
The key is generated by reading the C value. The generated key is set in the IC card as an initial encryption key.

FIG. 6 is a diagram for explaining a key update process in the IC card. In the IC card, when the update time is determined based on the date information from the host computer as shown in FIG. 4, an exclusive OR (XOR) of the ATC value and the current key is obtained, and a new key is generated. Update. Of course, not only XOR but also other calculation methods can be used. Thus, the key is updated according to the number of card transactions up to the time of the key update process.

FIG. 7 is a diagram for explaining an initial key generation process on the host computer side. The host computer generates a current key for each card as an exclusive OR of the master key for generating an individual key managed by itself and the PAN, PAN sequence number, and card serial number read from the IC card. This current key is IC
Set as the initial encryption key on the card.

FIG. 8 is a diagram for explaining a key update process on the host computer side.

The host computer reads the key update schedule data and the ATC value held in the IC card in an online process for performing risk management, and calculates the exclusive OR of the current key of each card and the ATC value at the update timing. To update to a new individual key.

FIG. 9 is a diagram showing a key update processing flow.
When the IC card is set in the terminal device, the power of the IC card is turned on and activated (step S1), selection and initialization of applications (VISA, MASTER, JCB, etc.), and counting up of ATC are performed (step S1).
2, S3). Next, it is determined whether or not the key update table has been registered (step S4), and if not, the update process ends. If the key update table is registered, it is determined whether the first scheduled update date has passed (step S5), and if it has passed, it is determined whether the first key has already been updated (step S6). If the key has not been updated, the key is generated and updated (step S7). If the scheduled update date has not passed in step S5, or if the first key has been updated in step S6, it is determined whether another scheduled key update date has been set (step S8). In this case, it is determined whether the Nth key update scheduled date has passed (step S9). If it has passed, it is determined whether the Nth key update has already been performed (step S10).
If the key has been updated, the process directly proceeds to step S8. If the key has not been updated, the key is generated and updated (step S8).
11) Then, the process proceeds to step S8. In this way, the same process is repeated until there is no new scheduled update date, and the update process ends when the new scheduled update date disappears.

[0018]

As described above, according to the present invention, the IC card itself generates and stores data relating to the key to be updated, and automatically updates the key when the update time comes. There is no need to set up a center for card processing, and keys can be updated safely.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a transaction system using an IC card.

FIG. 2 is a diagram showing secret key data stored during IC card issuance processing.

FIG. 3 is a view showing a scheduled update date table showing key update timings registered in the IC card.

FIG. 4 is a conceptual diagram illustrating key update in an IC card.

FIG. 5 is a diagram showing data used for key update processing.

FIG. 6 is a diagram illustrating a key update process in an IC card.

FIG. 7 is a diagram illustrating an initial key generation process on the host computer side.

FIG. 8 is a diagram illustrating key update processing on the host computer side.

FIG. 9 is a diagram showing a key update processing flow.

[Explanation of symbols]

1. IC card, 2. Terminal device, 3. Host computer.

Claims (4)

[Claims] 1. A system for storing an encryption key in an IC card having an arithmetic unit and a storage device and encrypting and transmitting data between a terminal device and a host computer. An IC card with a data update function, wherein a scheduled key update date is registered, and the encryption key is updated in the IC card after the scheduled update date. 2. The IC card generates a new key by calculating from current encryption key data and transaction count data,
The IC card according to claim 1, wherein the IC card is updated. 3. The IC card according to claim 1, wherein the IC card determines an update time based on external time information and a scheduled update date. 4. The IC card according to claim 1, wherein an encryption key calculated by a host computer from data relating to the IC card and a master key is set as an initial encryption key of the IC card.