JPH09134413A - Non-contact type data carrier system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data carrier system capable of executing different ciphering processing in each series of communication. SOLUTION: Plural key data for determining ciphering processing are previously prepared and a data table consisting of the plural key data is previously stored in a ROM 8 built in a reader/writer 2 and a ROM 16 or an electrically erasable programmable read-only memory(EEPROM) 14 built in a data carrier 10. At the time of starting communication, either one of the reader/writer 2 and the data carrier 10 determines key data to be used for ciphering processing and transmits position data indicating the position of the key data stored in the data table. The other device receiving the position data selects the key data from the data table based upon the position data. Then both the reader/ writer 2 and data carrier 10 execute ciphering processing using the same key data up to the end of a series of communication.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a communication function and a data carrier used for an ID card, commuter pass, prepaid card, etc., which is composed of an IC card having a readable / rewritable memory and a communication function. leader/
It consists of a writer and can read and rewrite data from the reader / writer to the memory built in the data carrier by non-contact data communication such as electromagnetic coupling method, electromagnetic induction method, optical method, radio wave method, etc. The present invention relates to a contactless data carrier system.

[0002]

2. Description of the Related Art At present, as a data carrier generally used in a non-contact type data carrier system, an EEPROM (Electri) which is electrically rewritable in a CPU, a mask ROM, a RAM, various peripheral elements and the like is used.
cally Erasable Programmable
Read only memory) or a built-in dedicated IC chip configured by adding a non-rewritable PROM, and a dedicated IC configured a logic circuit by a gate array with a combination of EEPROM or PROM, vinyl chloride, It is sealed with a resin mold or the like.

The non-contact type data carrier system having these data carriers does not have a connection terminal for data input / output with the outside and is non-contact type by an electromagnetic coupling method, an electromagnetic induction method, an optical method, a radio wave method, etc. Since data communication between the reader / writer and the data carrier can be performed and the data stored in the memory inside the data carrier can be read or rewritten, the influence of water, dust, static electricity, etc. It has excellent environmental resistance.

Further, the data carrier of these non-contact type data carrier systems does not have to be inserted into a reader / writer like a conventional contact type IC card or magnetic card which needs to be brought into contact with a connection terminal or a magnetic head. Since it operates just by holding it over a dedicated reader / writer, operability is improved.

[0005]

Since the non-contact type data carrier system handles data such as ID data and monetary data, it goes without saying that security is required. Therefore, various methods such as the data communication method, the data modulation / demodulation method, and the data configuration are adopted for the non-contact data communication,
They contribute to the improvement of security.

However, even if the contents of the communication data between the reader / writer and the data carrier are difficult to decipher, the communication signal itself, for example, a modulated signal such as electromagnetic wave or light is communicated. Also, it is easy to capture it by using a coil other than the data carrier or a light receiving element. In this way, when the same signal as the captured signal is transmitted to the reader / writer or the data carrier, there is a possibility of malfunction. In addition, it is fully expected that this may be used for illegal purposes.

The present invention has been made to solve such a problem, and data for determining an encryption process is used as key data at each start of a series of communication, and is used by either a reader / writer or a data carrier. A means for determining, a means for notifying the other of the key data determined by either the reader / writer or the data carrier, and the key data is changed for each series of processing, so that the encryption processing is always performed. The present invention provides a contactless data carrier system that prevents changes and malfunctions due to unauthorized operations and improves security.

[0008]

That is, according to the present invention,
It consists of a data carrier and a reader / writer that perform wireless data communication with each other, and the data carrier has a writable data memory, and reads data in the data memory based on a read command, A function of transmitting to the reader / writer as a transmission signal, a function of receiving a transmission signal from the reader / writer as a reception signal, a function of transmitting the read command in response to a read command in the received signal, And a function of writing the write data in the reception signal in the data memory, and the reader / writer receives the transmission signal of the data carrier side and acquires the data in the data memory. , The read command to read the data in the data memory or the write to write in the data memory In a contactless data carrier system having a function of transmitting data as a transmission signal on the reader / writer side, each of the reader / writer and the data carrier performs an encryption process on communication data between them. Encryption key data memory for storing a plurality of different encryption key data as a table, and a specific one of the encryption key data is selected as the specific encryption key data at the start of communication, and is transmitted. It has an encryption means for encrypting data on the basis of the specific encryption key data, and a decryption means for decrypting a received signal on the basis of the specific encryption key data. A contactless data carrier system is obtained which is characterized in that different encryption processes can be selected.

Further, according to the present invention, in the contactless data carrier system, the table of the encryption key data has a key code unique to each encryption key data, and the data carrier is: When the reader / writer-side transmission signal is received, a means for selecting the specific encrypted key data and a key code of the specific encrypted key data is notified to the reader / writer as one of carrier-side transmission data. A contactless data carrier system is provided.

Further, according to the present invention, in the contactless data carrier system, the table of the encryption key data has a key code unique to each encryption key data, and the reader / writer is , At the start of the transmission, means for selecting the specific encrypted key data, and means for notifying the reader / writer of the key code of the specific encrypted key data as one of the transmission data on the reader / writer side. A contactless data carrier system characterized by the above is obtained.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

A contactless data carrier system 1 according to an embodiment of the present invention comprises a reader / writer 2 as shown in FIG.
And a data carrier 10.

In the reader / writer 2, the oscillator 3 is
A signal of a constant frequency is sent to the modulation circuit 5, and CP
The control circuit 4 mainly composed of U
A command message including a command code and data indicating a request for reading or writing data to the EEPROM 14 of 0 is created, and the created command message is sent to the modulation circuit 5. The modulation circuit 5 uses the signal received from the oscillator 3 to modulate the command message received from the control circuit 4 and sends it to the transmission / reception circuit 6. Transmitter / receiver circuit 6
Transmits the command message received from the modulation circuit 5 to the data carrier 10, receives the response message described later transmitted from the data carrier 10, and sends the received response message to the demodulation circuit 7. Demodulation circuit 7
Demodulates the response message received from the transmission / reception circuit 6,
It is sent to the control circuit 4.

On the other hand, in the data carrier 10, the transmission / reception circuit 11 receives the command message transmitted from the reader / writer 2 and sends it to the demodulation circuit 12. The demodulation circuit 12 demodulates the command message received from the transmission / reception circuit 11 and sends it to the control circuit 13. The control circuit 13 follows the command telegram demodulated by the demodulation circuit 12 and
The ROM 14 is read or written, a response message including a response code and data is created, and the created response message is sent to the modulation circuit 15. The modulation circuit 15 modulates the response message received from the control circuit 13 and sends it to the transmission / reception circuit 11. The transmission / reception circuit 11 transmits the modulated response message received from the modulation circuit 15 to the reader / writer 2.

The user circuit 9 controls the reader / writer 2, and a personal computer (PC) is used as an example in the embodiment of the present invention. Further, both the ROM 8 in the reader / writer 2 and the ROM 16 in the data carrier 10 store programs for controlling their respective operations.

Here, in the embodiment of the present invention,
ROM 8 and data carrier 10 in the reader / writer 2
The ROM 16 therein further stores a program for encryption processing, a program for decryption, and a data table that determines the encryption processing, as will be described later. Reader / writer 2 and data carrier 10
Performs the encryption processing as software by executing these programs by their respective control circuits.

The ROM 8 in the reader / writer 2 described above
And a program for encryption processing stored in the ROM 16 in the data carrier 10, a program for decryption, a data table that determines the encryption processing, and a control circuit executing those programs. The encryption processing may be performed by hardware by separately configuring a circuit having the function of or a circuit performing a part of the functions.

Next, the encryption processing according to the embodiment of the present invention will be described.

First, in the contactless data carrier system 1 according to the embodiment of the present invention, the encryption processing algorithm used for communication between the reader / writer 2 and the data carrier 10 is determined in advance. There is. Here, as a simple example, the encryption process will be described using the function y = (x XOR a) + b. Note that y is the 1-byte data resulting from the encryption processing, and x is the 1-byte data before the encryption processing.
In the byte data, a and b show each 1-byte key data that determines this encryption processing. The encryption process uses this formula to perform a simple exclusive OR (XOR)
It is done by addition. It should be noted that this calculation is performed for each byte and is ignored when a carry occurs. The decryption process may be performed by reversing the formula used for the encryption process, and x = (y−b) XOR a
Becomes

What determines these encryption processes is a
And key data such as b. In the non-contact type data carrier system 1 of the present invention, a plurality of sets of these key data are prepared, and the ROM 8 in the reader / writer 2 and the ROM 16 or EEPRO in the data carrier 10 are prepared.
The same data table as shown in FIG. 2 is stored in M14. Here, in FIG. 2, n is a code of each key data, that is, a key code, and in this embodiment, position data indicating which key data is at which number in the data table. .

When the data carrier 10 enters the communication area with the reader / writer 2 and the existence of each other is confirmed by communication, in either the reader / writer 2 or the data carrier 10, the key data such as a and b described above is used. Is randomly selected. Further, when one of the reader / writer 2 and the data carrier 10 selects and determines the key data, it notifies the other by position data indicating the position in the data table of the selected and determined key data by communication.

Reader / writer 2 and data carrier 10
When one notifies the other of the position data indicating which key data is selected and determined, the other can recognize the same key data. Using the data, that is, a and b, the contents of the data transmitted and received between the reader / writer 2 and the data carrier 10 are encrypted and decrypted, respectively, and the encrypted data is used. Will be done. In addition, here, the same key data is used until a series of communication is completed.

As a result, since the communication itself is encrypted, it becomes difficult to decipher, and since the key data that determines the encryption is changed for each series of communication, the communication signal previously captured due to an unauthorized purpose is changed. Even if an imitated signal is sent from the outside, the contents cannot be correctly decoded in the next series of communications, so that a malfunction can be prevented. Further, the key data selected and determined that determines the encryption process does not appear directly on the communication, which makes it more difficult to decrypt the encrypted data.

What has been described above is common to the following first and second embodiments.

(First Embodiment) The operation of the contactless data carrier system 1 of the first embodiment will be described below with reference to FIGS. 3 to 6.

In the contactless data carrier system 1 of the first embodiment, the data carrier 10 selects and determines the key data that determines the encryption, and the position data indicating the position of the selected and determined key data in the data table. Is transmitted to the reader / writer 2 to enable communication of the encrypted data.

First, the operation of the reader / writer 2 will be described with reference to FIG. The reader / writer 2 sets the start command in the command code according to the command message format shown in FIG. 5, and transmits the command message including the start command at a constant cycle (S101). here,
In FIG. 5, STX (02) means a command message start code, ETX (03) means an end code of the command message, and BCC (Block Check Character) is an exclusive OR from the next to the ETX. It means to set the calculation result of (XOR). Next, reader / writer 2
If the data carrier 10 is in the communicable area, the data carrier 10 transmits a response message for this command message, and therefore it is determined whether or not the response message is received (S102). The reader / writer 2
Unless the response message is received from the data carrier 10, the process returns to step S101 and the command message is continuously transmitted. When the response message from the data carrier 10 is received, the response message contains position data indicating the position in the data table of the key data selected and determined by the data carrier 10, as will be described later. 2 acquires position data (S10)
3) You can. When the reader / writer 2 acquires the position data, the reader / writer 2 selects the selected key data of the data carrier 10 from the data table composed of a plurality of key data based on the position data (S104).

The reader / writer 2 thereafter communicates with the data carrier 10 by a telegram encrypted using this key data until a series of communications is completed.

The reader / writer 2 uses the key data selected in step S104 to encrypt the command code and data of the command message according to the command message format by the encrypting means by the encrypting means. Command message is created and the encrypted command message is transmitted to the data carrier 10 (S105). When the data carrier 10 receives this command message, it sends an encrypted response message corresponding to this command message, so the reader / writer 2 determines whether this response message has been received (S106). Unless the reader / writer 2 receives the response message from the data carrier 10, the reader / writer 2 returns to step S105 and continues to transmit the encrypted command message to the data carrier 10.
When the reader / writer 2 receives the encrypted response message, the reader / writer 2 decrypts the encrypted response message by the decryption means (S107). After that, it is determined whether or not the communication is to be ended (S108), and when the communication is not to be ended, the process returns to step S105 and a series of operations is repeated. When ending the communication, the reader / writer 2 creates an encrypted command electronic message by performing an encryption process on the command electronic message including the command code indicating the end of the communication by the encryption means. A command message indicating the end of encrypted communication is transmitted to (S
109). When the data carrier 10 receives this command message, it sends an encrypted response message for this command message, so the reader / writer 2
Whether or not this response message has been received is determined (S11).
0). Unless the response message from the data carrier 10 is received, the reader / writer 2 returns to step S109 and sends the encrypted command message to the data carrier 10.
Keep sending to. When the reader / writer 2 receives the encrypted response message, the reader / writer 2 decrypts the encrypted response message by the decryption means (S111) and ends the series of communication.

Next, referring to FIG. 4, the data carrier 10 will be described.
Will be described. When the data carrier 10 is supplied with power from a power supply (not shown), the value n of the position data is set to 0 as an initial value (S201). After that, until the command message including the activation command is received from the reader / writer 2, it is determined whether or not the command message including the activation command is received at a constant cycle (S20).
2). The data carrier 10 adds 1 to the value n of the position data unless it receives this command message (S20
3) and returns to step S202. Here, since the data table used in the present embodiment is the one shown in FIG. 2, the position data has an upper limit. Therefore, in step S203, when 1 is added and then the value of n exceeds 0Fh, 10h is subtracted from the value of n. Next, when the data carrier 10 receives the command message including the activation command from the reader / writer 2, the data carrier 10 determines the position data from the value of n (S204), and according to the determined position data, the key is read from the data table. Data is selected and determined (S205).
After that, the data carrier 10 creates a response message in which the value of the response code and the value of the position data are set according to the response message format of FIG. 6, and transmits the created response message to the reader / writer 2 (S20).
6). Here, ST in the response message shown in FIG.
X (02), ETX (03), and BCC have the same meaning as in the above-mentioned command message.

From then on, the data carrier 10 communicates with the reader / writer 2 by a telegram encrypted using this key data until a series of communications is completed.

Here, using the data table of FIG.
The encryption process will be described. The encryption process is performed on the command code and data in the above-mentioned command message and on the response code and data in the response message. For example, if the position data determined by the data carrier 10 is 8, the key data consisting of a and b are a = 71h and b = F, respectively.
2h. If the command code or response code is 31 and the data is 55, the command message or response message before the encryption process is 0.
It becomes 2 31 5503 67. For the command code or response code and data of this command message or response message, y = (x XOR 7
When the encryption process of 1) + F2 is performed, 02 32
It becomes 16 03 27. Conversely, the decryption process is x
= (Y-F2) XOR 71.

The data carrier 10 is a reader / writer 2
When the encrypted command message is received from (S
207), the encrypted command message is decrypted using the selected and determined key data, and the encrypted command message is decrypted (S208).
Next, the data carrier 10 determines whether or not the decrypted command message indicates the end of communication (S).
209). If the command message does not indicate the end of communication, the data carrier 10 transmits the encrypted response message to the reader / writer 2 (S210), returns to step S207, and returns the next encrypted command message. Wait until you receive it. In step S209, when the deciphered command message indicates the end of communication, the data carrier 10 creates an encrypted response message corresponding to the command message and sends it to the reader / writer 2. Then, (S211), a series of communication ends.

In this way, the non-contact type data carrier system 1 including the data carrier 10 and the reader / writer 2 according to the first embodiment of the present invention uses the key data used for the encryption process for each series of communication. It is possible to change the encryption, and it is possible to perform different encryption processing for each communication.

(Second Embodiment) Next, the operation of the non-contact type data carrier system 1 of the second embodiment will be described with reference to FIG.
It will be described with reference to FIGS.

In the contactless data carrier system 1 of the second embodiment, unlike the first embodiment, the reader / writer 2 selects and determines the key data that determines the encryption, and the selection is determined. By transmitting the position data indicating the position of the key data in the data table to the data carrier 10, the encrypted data can be communicated. The encryption process and the decryption process are the same as those in the first embodiment.

First, the operation of the reader / writer 2 will be described with reference to FIG. The reader / writer 2 uses the position data value n
The initial value 0 is set to (S301). Next, the leader /
The writer 2 sets the start command in the command code according to the command message format shown in FIG.
A command message including a start command is transmitted at regular intervals (S302). Next, if the data carrier 10 is in the communicable area, the reader / writer 2 determines whether or not the response message has been received because the data carrier 10 sends a response message to this command message (S303). ). When the reader / writer 2 does not receive the response message from the data carrier 10, the reader / writer 2 adds 1 to the value n of the position data (S304), and the step S2
It returns to 02 and continues transmitting the command message. Where n
Is greater than 0F, the same operation as the operation in step S203 of the data carrier 10 of the first embodiment is performed.

Upon receiving the response message from the data carrier 10, the reader / writer 2 determines the position data from the value of n (S305), and according to the position data, determines the key data to be used for the encryption process from the data table. Yes (S305). After that, the reader / writer 2 transmits the command message including the position data to the data carrier 10 (S307), and determines whether the response message from the data carrier 10 is received (S308). In step S308, if the response message from the data carrier 10 is not received, the reader / writer 2
Returns to step S307 and transmits again the command message including the position data to the data carrier 10.

On the other hand, when the response message from the data carrier 10 is received in step S308, the reader / writer 2 is thereafter subjected to the encryption process using the selected and determined key data until the series of communication is completed. Communication with the data carrier 10 is carried out by a telegram.

When the response message from the data carrier 10 is received in step S308, the reader / writer 2 encrypts the command code and the data of the command message according to the command message format using the selected and determined key data. By means of means, encryption processing is performed to create an encrypted command message, and the data carrier 1
Send the command message encrypted to 0 (S30
9). When the data carrier 10 receives this command message, it sends an encrypted response message for this command message, so the reader / writer 2 determines whether or not this response message has been received (S310).
The reader / writer 2 returns to step S309 unless the response message from the data carrier 10 is received,
Continue to send the encrypted command message to the data carrier 10. When the reader / writer 2 receives the encrypted response message, the reader / writer 2 decrypts the encrypted response message by the decryption means (S311). After that, it is determined whether or not the communication is to be ended (S312). If the communication is not to be ended, the process returns to step S309 to repeat a series of operations. When ending the communication, the reader / writer 2 performs an encryption process on the command message including the command code indicating the end of the communication by the encryption means to create an encrypted command message, and the data carrier 1
A command message that indicates the end of communication encrypted to 0 is transmitted (S313). When the data carrier 10 receives this command message, it sends an encrypted response message for this command message, so the reader / writer 2 determines whether or not this response message has been received (S314). The reader / writer 2 is the data carrier 1
Unless a response message from 0 is received, step S
Returning to 313, the encrypted command message is continuously transmitted to the data carrier 10. When the reader / writer 2 receives the encrypted response message, the reader / writer 2 decrypts the encrypted response message by the decryption means (S31).
5) Then, a series of communication ends.

Next, referring to FIG. 8, the data carrier 10 will be described.
Will be described. When the data carrier 10 is supplied with power from a power supply (not shown), thereafter receives a command message including a start command at a constant cycle until receiving a command message including a start command from the reader / writer 2. It is determined whether (S401). When the data carrier 10 receives the command message including the activation command from the reader / writer 2, the data carrier 10 creates a response message according to the response message format of FIG. 6, and transmits the created response message to the reader / writer 2 (S
402). Next, when the command message including the position data transmitted from the reader / writer 2 is received (S403),
The data carrier 10 creates a response message for this command message and sends the response message to the reader / writer 2 (S404). After the transmission, the key data selected and determined by the reader / writer 2 is selected from the data table using the position data included in the received command message described above (S405).

The data carrier 10 thereafter communicates with the reader / writer 2 by a telegram encrypted using this key data until a series of communications is completed.

The data carrier 10 is a reader / writer 2
When the encrypted command message is received from (S
406), the encrypted command message is decrypted using the selected and determined key data, and the encrypted command message is decrypted (S407).
Next, the data carrier 10 determines whether or not the decrypted command message indicates the end of communication (S).
408). If the command message does not indicate the end of communication, the data carrier 10 transmits the encrypted response message to the reader / writer 2 (S409), returns to step S406, and returns the next encrypted command message. Wait until you receive it. In step S408, when the deciphered command message indicates the end of communication, the data carrier 10 creates an encrypted response message corresponding to the command message and sends it to the reader / writer 2. Then, (S410), a series of communication ends.

As described above, the non-contact type data carrier system 1 including the data carrier 10 and the reader / writer 2 according to the second embodiment of the present invention uses the key data used for the encryption process for each series of communication. It is possible to change the encryption, and it is possible to perform different encryption processing for each communication.

In this embodiment, in order to briefly explain the operation of the encryption process, the above-mentioned simple formula and the data table having the contents shown in FIG. 2 have been used as an example. However, the contents of the formula and the data table can be arbitrarily selected and determined and are not limited to the present embodiment.

In this embodiment, the position data n is determined by simply adding 1 and looping until a specific condition is satisfied, but a method of generating a random number or the like is also possible. Well, it is not limited to the present embodiment.

It is also possible to store the determined position data in the internal memory so that the same data will not be obtained the next time communication is performed.

In the present embodiment, the encryption process and the decryption process are performed on the command code and data of the command message and the response code and data of the response message. Alternatively, the processing may be performed on only one of the data and is not limited to this embodiment.

In the present embodiment, the command message and the response message shown in FIGS. 5 and 6 are used, but other formats may be used and the present invention is not limited to this embodiment.

Further, in the present embodiment, the encryption process using the above formula and data table is performed only once for each communication.
As an alternative, data indicating how many times the encryption process should be performed for each communication may be stored in advance, and the encryption process may be performed according to the data.

[0051]

[Embodiment] In the embodiments, the electromagnetic coupling system is adopted as the communication system.

[0052]

As described above, according to the present invention, the key data that determines the encryption process used for the communication between the data carrier and the reader / writer in the contactless data carrier system can be directly transmitted. Can be specified without revealing it, and by changing the key data for each series of communication, different encryption processing can be performed for each communication,
A contactless data carrier system with improved communication security can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a contactless data carrier system of the present invention.

FIG. 2 is a diagram showing a data table used in the embodiment of the present invention.

FIG. 3 is a flowchart showing an outline of operation of the reader / writer in the first embodiment of the present invention.

FIG. 4 is a flowchart showing an outline of operation of a data carrier according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a command message used in the embodiment of the present invention.

FIG. 6 is a diagram showing a response message used in the embodiment of the present invention.

FIG. 7 is a flowchart showing an outline of operation of a reader / writer according to the second embodiment of the present invention.

FIG. 8 is a flowchart showing an outline of operation of a data carrier according to the second embodiment of the present invention.

[Explanation of symbols]

 1 non-contact type data carrier system 2 reader / writer 3 oscillator 4 control circuit 5 modulation circuit 6 transmission / reception circuit 7 demodulation circuit 8 ROM 9 user circuit (PC) 10 data carrier 11 transmission / reception circuit 12 demodulation circuit 13 control circuit 14 EEPROM 15 modulation circuit 16 ROM

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H04L 9/18 H04L 9/00 651 12/28 11/00 310B

Claims (3)

[Claims] 1. A data carrier and a reader / writer that perform wireless data communication with each other, the data carrier having a writable data memory, and reading data in the data memory based on a read command. , A function of transmitting to the reader / writer as a transmission signal on the data carrier side, a function of receiving a transmission signal from the reader / writer as a reception signal, and transmitting the read command in response to a read command in the reception signal And a function of writing the write data in the received signal into the data memory, wherein the reader / writer receives the transmission signal of the data carrier side and receives the data in the data memory. And a read command for reading the data in the data memory or a write in the data memory In a contactless data carrier system having a function of transmitting the write data to be transmitted as a transmission signal on the reader / writer side, each of the reader / writer and the data carrier encrypts communication data between them. Encryption key data memory for storing a plurality of different encryption key data for encryption processing as a table, and a specific one of the encryption key data is selected as specific encryption key data at the start of communication However, it has an encryption means for encrypting the transmission data on the basis of the specific encryption key data and a decryption means for decrypting the received signal on the basis of the specific encryption key data. A non-contact type data carrier system characterized in that different encryption processes can be selected. 2. The contactless data carrier system according to claim 1, wherein the encryption key data table has a key code unique to each encryption key data, and the data carrier is the reader / reader. Means for selecting the specific encrypted key data when receiving the writer side transmission signal, and means for notifying the reader / writer of the key code of the specific encrypted key data as one of the carrier side transmission data. A non-contact type data carrier system comprising: 3. The contactless data carrier system according to claim 1, wherein the table of the encrypted key data has a key code unique to each encrypted key data, and the reader / writer transmits the key code. At the time of starting, it has means for selecting the specific encrypted key data, and means for notifying the reader / writer of the key code of the specific encrypted key data as one of the transmission data on the reader / writer side. Contactless data carrier system.