JPS61205041A - Communication network system - Google Patents

Abstract

PURPOSE:To prevent completely the unjust use of a coded telegram at the transmission and reception terminal sides by sealing a ciphering device and a decoder into one body within an equipment in a decoding unable state and using a secret key proper to ciphering device and the encoder respectively to perform the ciphering and decoding jobs with different algorithms. CONSTITUTION:A center terminal 12 set at the telegram receiver side, e.g., a bank, a department store, etc. is connected to customer terminals 11a-11n set at the telegram transmitter side, e.g., a private home, a company, etc. via communication circuits 13a-13n respectively. Each terminal 11 contains a card reader/writer 21 to which IC cards 14 (14a-14n) are inserted, an input device 22 consisting of a keyboard, for example, which supplies a telegram M, i.e., the communication information to the card 14 via the reader/writer 21 and a communication interface 23 which transmits a coded telegram M' produced by the card 14 with input of the telegram M to the receiver side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a communication network system useful for commercial transactions, document transmission, and the like.

[Technical background of the invention and its problems]

BACKGROUND ART In recent years, with the improvement of communication networks, various systems such as home banking, home shopping, farm banking, etc., which take full advantage of the advantages of the above communication networks, are being developed. The biggest challenge in realizing such a system is how to safely carry out business transactions and document communications that are conducted in situations where neither party can see the other party, and how to ensure that the transaction documents can be used as evidence. That's the point.

That is, in transactions and document communications conducted using this type of communication network, typical examples of fraud include false declarations and forgery of transaction documents.

This false declaration can be made, for example, by a sender who has sent information but declares to the recipient that he or she has no recollection of sending such information; , means to declare that you have indeed sent the information. Forgery of transaction documents is, for example, when the receiver falsifies (rewrites) the contents of the correspondence received and recorded in the transaction without permission.
It means to falsify or to forge. Such fraud can lead to fraud in transactions and misappropriation of money.

Conventionally, in order to prevent such fraud as much as possible, DE S (D
ata Encryption Standard
An encryption/decryption circuit equipped with a commonly used encryption program such as Data Encryption Standard (Data Encryption Standard) is installed to encrypt and communicate communication information.

That is, at the sending terminal A, the encryption circuit 2 is sent via the input device 1.
The electronic message, which is communication information input to the computer, is encrypted according to the keyword registered in the key memory 3, and is transmitted via the communication interface 5 connected to the communication line 4.

At the receiving terminal B, the encrypted message received from the communication line 4 via the communication interface 6 is input to the decryption circuit 7, decrypted according to the keyword registered in the key memory 8, and the communication information is output to the output device 9. I am trying to output from . In this case, the keywords are the two communication terminals A.

A unique one is used between 8 and 8 stations, and the contents of the communication are not leaked to anyone other than the customers involved in the communication.

Therefore, if it is assumed that the keywords registered in the keyword memory 8 on the receiving terminal B side are managed so as not to be leaked to the outside, and that the recipient does not commit fraud such as forging communication information, then the encryption of the above-mentioned message Only the sending terminal A that knows the keyword can perform the conversion. Therefore, for example, if the encrypted message is stored as is at the receiving terminal B, only the sending terminal A can create the encrypted message, so it is possible to apply a so-called digital signature to the communication information. Become. Then, it becomes possible to give evidence to the encrypted message.

However, in general, it is possible for a recipient who knows the content of the keyword to create an encryption program using another computer, etc., and use that keyword without permission to create an encrypted message. It is.

Therefore, it is extremely problematic to assume that no fraud is committed at receiving terminal B.

For these reasons, conventional communication network systems have problems in reliably preventing fraud on the sending and receiving sides, and ultimately fail to ensure the safety of commercial transactions.

[Purpose of the invention]

The present invention has been made in consideration of these circumstances, and its purpose is to enable reliable digital signatures on communication information and to ensure sufficient security for commercial transactions and document communications, for example. The goal is to provide a communications network system that can

[Summary of the Invention] The present invention provides a communication network system in which one or more senders are each provided with a sender-specific encryption device, and only one receiver is provided with a decryption device. The encryption device is equipped with: (1) a storage unit that stores a private key determined for each encryption device in a manner that cannot be read externally; An encryption unit to be encrypted is integrated as, for example, a semiconductor device, and this is sealed and integrated inside a portable card, and
On the other hand, the decryption device includes: (1) a storage unit that stores all of the private keys determined for each of the encryption devices in a manner that cannot be read externally; and (2) a key selection unit that selects one of these private keys. ■
a decryption unit that decodes a signal encrypted and communicated from the encryption device using at least the private key selected by the key selection unit using an algorithm different from the encryption algorithm; It is characterized by being integrated and sealed and integrated inside a portable card.

Also, prepare an encryption device for only one sender, and
In a communication network system in which one or more recipients are each provided with a recipient-specific decryption device, the encryption device is configured such that: A memory unit that can be stored and ■
a key selection unit that selects one of these secret keys, and an encryption unit that encrypts communication information using a predetermined algorithm using at least the secret key stored in this storage device;
For example, it is integrated as a semiconductor device and is sealed and integrated inside a portable card, and the decryption device is configured such that: (1) the private key determined for each decryption device cannot be read out to the outside; (1) A decryption unit that decrypts a signal encrypted and communicated from the encryption device using at least the private key and using an algorithm different from the encryption algorithm; The present invention is characterized in that it is integrated as a device and is sealed and integrated inside a portable card.

〔Effect of the invention〕

Thus, according to the present invention, the encryption device and the decryption device are sealed and integrated inside the device in such a manner that the encryption and decryption processes cannot be deciphered. , and since encryption and decryption are performed using different algorithms, it is possible to reliably prevent fraud on the encrypted message on both the sending terminal side and the receiving terminal side.

In other words, the only thing that can create an encrypted message for communication information is the sending terminal that is equipped with the encryption device, or the only one that can decrypt the encrypted message is the receiving terminal that is equipped with the decryption device. .

Therefore, for example, by recording and storing the received encrypted message, it is possible to apply a highly reliable digital signature to the encrypted message. Therefore, it becomes possible to improve the reliability and security of commercial transactions and document transmission using a communication network, and it is possible to achieve great practical effects such as increasing the evidentiary capacity of recorded communication information.

Embodiment of the Invention] An embodiment of the invention will be described below with reference to the drawings.

1 to 5 show a first embodiment, which is a communication network system applicable to, for example, home banking, home shopping, farm banking, etc. As shown in FIG. 5, this embodiment system includes a plurality of customer terminals 11a, 11b, to 11n installed at customer sides such as households and businesses that are message senders, and a bank that is a message receiver. Communication lines 13a and 1 are connected to the center side terminal 12 installed at the only center side such as
3b, to 13n are connected through each separately. Portable so-called IC cards 14a, 14b, to 14n are attached to the customer terminals 11a, 11b, .about.11n, and a portable IC card 15 is attached to the center terminal 12. .

As shown in FIG. 1, customer terminals 11 (11a, 11b,
~11n) are IC cards 14 (14a, 14b,
~14n) is attached to the card reader/writer 21
and the above IC via this card reader/writer 21.
An input device 22 consisting of a keyboard, for example, for inputting the message M, which is communication information, into the card 14, and a communication device 22 for inputting the message M and transmitting the encrypted message M' created by the IC card 14 to the receiving side. and an interface 23. In addition, the center side terminal 12 has a communication line 13 (1
3a, 13b, ~13n), a communication interface 25 that receives the encrypted message M' transmitted via the 3a, 13b, ~13n), a recording device 26 such as a disk device that records and stores the received encrypted message M', and the IC card 15. A card reader/writer 27 is attached to input the received encrypted message M' into the IC card 15, and outputs the message M decrypted and reproduced by the IC card 15, and outputs the decrypted message M. It is composed of an output device 28 such as a printer, and a random number generation circuit 29 that generates a random number R used for specifying the transmission time of the message M.

Now, the IC card 14.15, which is the main component of this system, is of the same type as the one introduced in, for example, Japanese Patent Publication No. 53-6491, etc., and has an encryption card integrated inside it as a semiconductor device. It is constructed by sealing and integrating the device or decoding device.

Among the information stored therein, specific information such as a secret key and encryption/decryption algorithms, which will be described later, is stored in a state that cannot be read out to the outside.

For example, as shown in FIG. 2, the IC card 14 includes an input/output control circuit 31 that inputs and outputs necessary information to and from the card reader/writer 21, and three memories 32, 33, 34.
, first and second encryption circuits 35 and 36.

The random number R1 generated by the center side terminal 12 and given to the customer terminal 11 and the message M inputted via the input device 22 are taken into the IC card 14 via the input/output control circuit 31. The random number R is then stored in the memory 32 and given to the first encryption circuit 35, and the message M is given to the second encryption circuit 36. The first encryption circuit 35 stores the information stored in the memory 34 in advance in a state that cannot be read outside the device (IC card 14).
The random number R is encrypted according to a secret key KM unique to the C card (encryption device), and a keyword K used for encrypting the message M is created. This keyword is created as K=a, (R) kM+, where the secret key is KMi and the encryption algorithm of the first encryption circuit 35 is q. The second encryption circuit 36 encodes the input message M according to the keyword K created in this way.
is encrypted, and the encrypted message M' is sent to the input/output control device 31.
It is intended to be output via . The encryption of this message M is performed using the encryption algorithm of the second encryption circuit 36.
Then, M' = fk (M). When the encrypted message M' is output, a personal keyword I consisting of an ID number unique to the IC card registered in the memory 33 is output together with the encrypted message M'.

The encryption algorithm used in the first and second encryption circuits 35 and 36 is, for example, the above-mentioned DES.

On the other hand, the IC card 15, as shown in FIG.
, an encryption circuit 45, a decryption circuit 46, and a key extraction circuit 47. The input/output circuit 41 receives the encrypted message M' transmitted from the customer terminal 11 and the personal keyword 1. and a random number R generated at the center side terminal 12
is taken into the IC card 15. and random number R
is registered and stored in the memory 42 and given to the encryption circuit 45, the personal keyword I is registered and stored in the memory 43 and given to the key extraction circuit 47, and the encrypted message M'
is given to the decoding circuit 46. The memory 44 includes each of the IC cards (encryption devices) 14 (14a, 14b,
~14n) is assigned to each IC card-specific key KM (KMa.

KMb, -KMn) are all registered in advance in a state in which they cannot be read outside of the IC card (decoding device) 15.

The key extraction circuit 47 extracts the secret keys KMa and KMb registered in the memory 44 according to the personal keyword I.

〜KMn, selectively extracts the secret key KMi assigned to the IC card (encryption device on the communication partner side) specified by the above-mentioned personal keyword I, and extracts this secret key KMi from the encryption device 45.
is giving to Inputting this secret key KMi, the encryption circuit 45 encrypts the random number R and creates the same keyword K in the same manner as the encryption device on the communication partner side described above. Then, the decryption circuit 46 decrypts the encrypted message M' according to this keyword K, and reproduces the message M. This encrypted message M' is decrypted as M=f''K(M') when the decryption algorithm is f-1. This message M is sent to the IC card via the input/output device 41. The decryption algorithm f-1 used in the decryption circuit 46 is different from the encryption algorithm f used in the encryption device, that is, the decryption algorithm f4 to f is used. .

Figure 4 shows an IC card 14°15 configured as described above.
A customer terminal 11 and a center side terminal 1 each equipped with
This is a sequence of information communication performed between 2 and 2.

When a customer in possession of an IC card 14i sends a transaction message M to the center side, first the IC card T4 is sent to the customer terminal 11.
When i is set (step 51), the card reader
The writer 21 requests the center to generate a random number R (step 52). On the other hand, in the card reader/writer 41 of the center terminal 12 in which the IC card 15 is set (step 53), it is sequentially determined (step 54) whether or not the request for generating the random number R is accepted. In response to the request for generating a random number R, the random number generating circuit 29 generates a random number R and transmits it to the customer terminal 11 making the communication request (step 55). This random number R generation request and random number R
The preparation for communication of the message M is completed by the communication.

On the customer side, the random number R is stored in the memory 32 (step 56), and the message M input from the input device 22 is
The data is imported into the G card 141 (step 57).

This message M is encrypted as described above (step 58).
, the encrypted message M' is transmitted together with the personal keyword I (step 59).

The center terminal 12 that has received the encrypted message M' and the personal keyword I records and saves the encrypted message M' in the recording device 26 (step 60), and also records the encrypted message M' and the personal keyword I. r and the aforementioned random number R are loaded into the IC card 15 (step 61). Then, as mentioned above, the encrypted message M' is decrypted (step 6
2) is performed, and the decoded and reproduced message M is outputted via the output device 28 (step 63), and the information communication ends.

According to such a communication network system, fraud can be prevented in the following manner.

The first possible fraud is forging the encrypted message M' without using the IC card 14i. As mentioned above, when DES is used as the encryption algorithm, DES
Since this is well known, it is possible to create an equivalent algorithm using other computers.

However, the private key KMi is known only to a limited number of trusted people on the center side, and is unknown not only to customers but also to the majority of employees at the center side. Further, it is impossible to read this private key KMi from the IC card 14i or the IC card 15 to the outside.

For this reason, even if we were able to create an encryption algorithm,
Unable to create encryption key K. Therefore, it is impossible to decipher the encryption process and it is impossible to forge the encrypted message M'.

The next possibility is that the customer impersonates another customer and forges the encrypted message M' using his or her own IC card 14k. However, in this case as well, the secret 11KMi registered in the IC card 14i necessary for creating the encrypted message M' cannot be known, and it is different from the secret key KMk registered in the IC card 14k.
In the end, it becomes impossible to fake it.

On the other hand, it is also possible to forge the encrypted message M' using the IC card 15 on the center side. However, the I used on the center side
The C card 15 is not prepared with the decryption algorithm f-'L, and furthermore, it is impossible to encrypt the data.

In this way, in this system, those who can create the encrypted message M' are limited to those who possess the IC card 141, and it is impossible to forge it. Therefore, the above encrypted message M
A highly reliable digital signature can be achieved simply by recording and storing ′.

By the way, FIG. 6 is a schematic configuration diagram of another communication network system based on the same technical idea. This system connects a center side terminal 71 to communication lines 72a and 72b.
, ~72n to a plurality of customer terminals 73a.

13b to 73n to communicate the transaction document M.

Then, the center side terminal 71 performs encryption processing using the IC card 74, and each of the customer terminals 73a, 73b, .
3n is different from the above-described embodiment in that the decryption process of the encrypted message is performed using IC cards 75a, 75b, .about.75n.

In this case, the IC card 74 is realized by using the decryption circuit 46 of the IC card 15 shown in FIG. 3 as a second encryption circuit, and the IC card 75 (75a, 75b).

~75n) is the second IC card 14 shown in FIG.
This is realized by using the encryption circuit 36 as a decryption circuit.

Even if the network system is configured in this way, it is possible to make it impossible to forge the encrypted message M' as in the previous embodiment, and therefore it is possible to obtain the same effect as in the previous embodiment. Become.

Note that the present invention is not limited to the embodiments described above. For example, the IC card 14, 15, etc. can be realized as a portable block shape, a pencil shape, or the like. Moreover, algorithms other than DES can be used as encryption/decryption algorithms. However, even in this case, it is necessary to use different algorithms for encryption and decryption. Further, the functions of the IC cards 14 and 15 may be realized by a microcomputer and software. In addition, the communication information is not limited to the above-mentioned example, and in short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawing]

Figures 1 to 5 show an embodiment of the present invention; Figure 1 is a schematic diagram of the main parts, Figure 2 is a diagram of the configuration of the customer card, and Figure 3 is the configuration of the center card. , Figure 4 is a diagram showing the communication sequence, Figure 5 is a network configuration diagram, and Figure 6 is a diagram showing the communication sequence.
Figure 7 is a configuration diagram of a network according to another embodiment of the present invention.
The figure is a diagram showing a schematic configuration of a conventional network system. 11a, llb, ~11n, 73a, 73b, ~7
3n...Customer terminal, 12゜71...Center side terminal, 14a, 14b, ~14n, 15.74.75a
. 75b, ~75n-IC card, 32.33.34
．． 42.43°44...Memory, 35.36.45.
...Encryption circuit, 46...Decryption circuit, 47...Key extraction circuit. Applicant's agent Patent attorney Takehiko Suzue Figure 4, Figure 5B! ! 1

Claims (8)

[Claims] (1) A sender-specific encryption device prepared for each of one or more senders, and a decryption device prepared for only one receiver; A storage unit that stores a private key specified in the above in a manner that cannot be read externally, and an encryption unit that encrypts communication information using a predetermined algorithm using at least the private key stored in this storage device. The decryption device is configured in an integrated manner, and includes a storage unit that stores all of the secret keys determined for each encryption device in a manner that cannot be read externally, and a key selection unit that selects one of these secret keys. and a decryption unit that decrypts a signal encrypted and communicated from the encryption device using an algorithm different from the encryption algorithm using at least the private key selected by the key selection unit. A communication network system characterized by being configured in an integrated manner. (2) The communication network according to claim 1, wherein the encryption device and the decryption device are comprised of semiconductor devices sealed and provided inside a portable card.
system. (3) The encryption device and decryption device are based on the Data Encryption Standard (DES).
2. The communication network system according to claim 1, wherein the communication network system uses the encryption/decryption algorithm as an encryption/decryption algorithm. (4) The key selection unit includes a code storage unit that stores a code for identifying the encryption device that transmitted the encrypted and communicated signal, and the key selection unit performs the encryption according to the code stored in the code storage unit. 2. The communication network system according to claim 1, wherein a private key specified for a device is selectively extracted. (5) An encryption device prepared for only one sender;
and a receiver-specific decryption device prepared for each of one or more recipients, and the encryption device has a memory that stores all of the private keys determined for each decryption device in a manner that cannot be read externally. , a key selection section that selects one of these secret keys, and an encryption section that encrypts communication information with a predetermined algorithm using at least the secret key selected by the key selection section. The decoding device is configured as follows:
A storage unit that stores a private key determined for each decryption device in a manner that cannot be read externally, and at least the private key stored in this storage device are used to encrypt the encryption using an algorithm different from the encryption algorithm. 1. A communication network system characterized in that the communication network system is configured by sealing and integrating a decoding unit for decoding a signal transmitted in an encrypted form from an encryption device. (6) The communication network according to claim 5, wherein the encryption device and the decryption device are comprised of semiconductor devices sealed and provided inside a portable card.
system. (7) The encryption device and decryption device are based on the Data Encryption Standard (DES).
6. The communication network system according to claim 5, which uses the encryption/decryption algorithm as the encryption/decryption algorithm. (8) The key selection unit includes a code storage unit that stores a code for identifying the destination decoding device to which the encrypted signal is transmitted, and the key selection unit selects the decoding device according to the code stored in the code storage unit. 6. The communication network system according to claim 5, wherein a predetermined private key is selectively extracted.