JPH0916679A - Cipher communication equipment and its system - Google Patents

Abstract

PURPOSE: To suitably charge a user executing cipher communication. CONSTITUTION: Each of an information presenting side terminal 20 and a user side communication terminal 20 is provided with a ciphering device 21 having a respectively different cipher system and a cipher speed setting device 23 for selecting the cipher processing speed of the device 21. An amount corresponding to a cipher processing speed selected by a charging means included in an information preseting center is charged to a user. Consequently a cipher system can be selected in accordance with the cipher intensity corresponding to the cipher processing speed or the sort of information for ciphering a transmission speed and charging corresponding to the selected cipher system can be properly executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryptographic communication device and a cryptographic communication system used in a multimedia network or the like, and more particularly to charging for a confidential data providing service.

[0002]

2. Description of the Related Art In recent years, with the development of optical fiber networks in trunk communication networks, the spread of cable television systems, the practical use of satellite communication, the spread of local area networks, etc., various information has been provided using such communication networks. Then
Charges are collected according to the content and amount of the information. The so-called information service industry is increasing. In addition, it is considered to provide multimedia information such as moving image data, still image data, audio data, computer data as the information. In such a service that provides multimedia information, it is important to properly charge the provided information. However, the conventional billing system is a monthly billing system that is unrelated to the frequency of use such as a cable television system or satellite broadcasting, or a frequency of use that is unrelated to the type and quality of information such as computer usage (or In many cases, it was a billing method in which only the usage time) was counted.

On the other hand, in such a communication network, it is important to safely transmit information, and it is said that it is effective to use a cryptographic technique as a means therefor.
A detailed description of the actual encryption method will be given later, and here, a conventional information providing service using encryption technology will be described. As shown in FIG. 27, the cryptographic communication network that realizes the information providing service includes the information providing center 10 and users. The information providing center 10 and the user share a unique and secret key in advance. A, B, ..., M is the user of the _{network, K A, K B, ...} , K M each information center 1
0, the key shared between user A and the information providing center 10
, A key shared between user B and user B ... Information provision center 1
0 and the key shared by the user M are shown. Further, the information providing center 10 and each user have a communication terminal equipped with an encryption device for performing encryption (and decryption) according to an algorithm determined by the network and a communication interface, as shown in FIG. . The communication interface exchanges data between the communication terminal and the communication path.

For example, when the user A receives information from the information providing center 10, the information providing service using the conventional encryption method is performed in the following procedure. 1. The user A requests the information providing center to provide the information that he or she needs through the communication interface. 2. The information providing center sets the secret key K _A shared with the user _A in the encryption device in advance, encrypts the information provided by the encryption device, and sends the encrypted information to A via the communication interface. To do. 3. The user A receives the ciphertext from the information providing center via the communication interface, sets the secret key K _A shared with the information providing center in advance in the encryptor, and the encryptor sends the secret key K _A from the information providing center. Decrypt the received sentence and obtain the provided information.

By this procedure, an information providing service is provided between the information providing center and the authorized users who share the key. Further, since the information providing center can provide the information secretly to the users other than the user who wants to send the information, the user who sent the information can be charged for the information providing service. However, when the information providing center charges a fee for the information providing service by such a procedure, conventionally, the information providing center simply charges the communication time regardless of the type or quality of the information, or charges each time the information is provided. There were many different methods.

Here, the DES encryption will be briefly described as a conventional encryption method. In the DES encryption, encryption and decryption are performed in units of 64-bit data blocks, and the key length is 56 bits (64 bits when 8 parity bits are added). Cryptographic algorithms are basically transposed and substituting, and by repeating 16 steps of processing that combines transposition and substituting appropriately, the bit patterns of plaintexts are mixed and converted into ciphertexts that do not make sense. . When decrypting, the original plaintext is restored by stirring in reverse.

A parameter of this stirring method is designated by a 56-bit key. The number of key candidates is 2 56 (about 10
(17 to the 17th power), and when performing a brute force decryption, that is, a decryption in which the obtained ciphertext and plaintext pair is checked by changing the key once, 500ns per check
In this case (processing speed of 128 Mbps), it takes about 1000 years as a whole.

In the DES encryption process, first, the 64-bit plaintext is transposed (initial value IP). This initial value is fixed. The output of this transposition process is complicated 1
After transposing 6 steps of encryption processing, finally transpose (final transposition IP
^-1 ) is performed. This final transposition is also fixed.

The 64-bit data subjected to the initial transposition is divided into left and right by 32 bits, and the left half is L ₀ and the right half is R ₀ . The process shown in FIG. 29 is performed over 16 stages from L ₀ and R ₀ to L ₁₆ and R ₁₆ . That is, assuming that the left and right 32 bits at the end of the processing of the n-th stage are L _n and R _n , respectively, L _n and R _n are expressed by the following equation. L _n = R _n-1 R _n = L _n-1 #f (R _n-1 , K _n )

Here, # is exclusive of mod2 for each bit.
Means disjunction, K_nIs the 48 bits input to the nth stage
The key of L_n-1And R_n-1Is the output of the (n-1) th stage, f
Is R _n-1And K_nTo output 32-bit data
Function.

[0011]

As described above, in the service for providing multimedia information, the amount of information and the security required for communication vary greatly depending on the type of information provided. Therefore, in multimedia communication, it is necessary to start the communication after the transmission side and the reception side discuss the transmission speed and safety according to the type of information to be exchanged. Further, the fee system for the information providing service also needs to be a system according to the real-time property of communication required by the agreed transmission speed and safety and the load on the network.

However, in the conventional service for providing multimedia information, it has not been considered to make the encryption processing speed of the encryption device variable in the case of concealing communication information by encryption. For example, in the case of data such as video, which has a large capacity and requires high-speed real-time processing, the encryption processing speed of the encryption device is increased to achieve high-speed encrypted communication, and vice versa. In the case of small-capacity non-real-time data represented by a document, the encryption processing speed of the encryption device cannot be slowed to reduce the load on the encryption device.

Further, in the case of data that has a large capacity and requires high-speed real-time property, the encryption processing speed is increased to realize high-speed encrypted communication even if the security of the encryption is lowered to some extent. On the contrary, in the case of small-capacity non-real-time data represented by a document, the encryption process cannot be complicated and the encryption speed cannot be slowed down in order to improve security. Therefore, it is difficult to set the fee system for the information providing service to a system according to the transmission speed at the time of providing information and the security required for communication.
The conventional cryptographic communication has the above problems.

The present invention has been made in view of the above situation, and an object thereof is to provide a fee system according to the transmission speed and security for providing encrypted information.

[0015]

According to a first aspect of the present invention, an encryption transmission means for encrypting and transmitting data, a selection means for selecting an encryption processing speed in the encryption transmission means, and the selection means are selected. And a charging means for charging according to the encryption processing speed.

According to an eighth aspect of the present invention, there is provided an encryption communication system capable of communicating encrypted data via a network and variably setting the encryption strength, wherein the data transmission side is to the data reception side. The fee is charged according to the encryption strength.

[0017]

According to the present invention, the cryptographic communication with a high degree of freedom can be realized by selecting the cryptographic processing speed by the selecting means. Further, an information providing service having a fee system according to the encryption strength, transmission speed, and security of the selected encryption processing speed is realized.

[0018]

EXAMPLES Examples 1 to 9 will be described below, but each example is based on the following viewpoints. Example 1 An encryption (decryption) speed is set by preparing a plurality of clocks for a general encryption method,
The fee for the information providing service is charged according to the set speed. [Example 2] The encryption (decryption) speed is set by preparing a plurality of circuits for repeating the encryption process for a general encryption method, and the charge of the information providing service is set according to the set speed. Will be charged. [Third Embodiment] An encryption (decryption) speed is set by preparing a circuit that repeats the encryption processing for a general encryption method, and selecting the number of times the repetition processing is performed. The information service fee is charged accordingly. [Fourth Embodiment] By preparing a plurality of clocks for the pseudo random number generator, the generation speed is set, and the charge of the information providing service is charged according to the set speed. [Embodiment 5] By preparing a plurality of circuits for repeating the generation processing for the pseudo-random number generator, the generation speed is set, and the fee for the information providing service is charged according to the set speed. [Sixth Embodiment] An internal variable of a pseudo random number generator whose generation speed can be set can be read. [Embodiment 7] In the encryption system of Embodiment 7, one of the pseudo-random number generator and the encryption device that cannot set the processing speed is used. [Embodiment 8] An encryption (decryption) speed and a generation speed are set by setting a plurality of clocks for an encryption method including a pseudo-random number generator, a computing unit, and an encryption unit, and the set speed is set. The information service fee is charged accordingly. [Embodiment 9] The means for setting the encryption (decryption) speed and the pseudo random number generation speed is integrated with the encryption system of the seventh embodiment.

[Embodiment 1] In the present embodiment, the information providing center 10 and the user of the information providing service perform encryption (and decryption) according to an algorithm determined by the network as shown in FIG. Encrypted communication is performed using the communication terminal 20 including the communication interface 21, the communication interface 22, and the encryption speed setting device 23. The encryption device 21 can set the encryption speed by the encryption speed setting device 23. This can be realized, for example, by preparing a plurality of clocks having different frequencies as the clocks for operating the encryptor 21, and selecting the operation clock from among them according to the setting of the encryption speed from the outside.

FIG. 2 shows an example of the encryption speed setting device 23 according to this embodiment. The encryption speed setting device 23 of FIG.
It is composed of individual clock generators 23a and selectors 23b. CK _{qi of the} clock generator 23a generates a clock signal q _i . The clock signals q ₁ , q ₂ , ..., Q _t generated by each clock generator 23 a are input to the selector 23 b, and one of them is selected by the information providing server using the communication terminal 20 and the user. The selector 23b is controlled by the speed setting signal.

The communication interface 22 transmits information indicating the processing speed of encryption (decryption) and information indicating the processing speed of encryption (decryption) while transmitting the transmission text encrypted by the encryptor 21 to the transmission path. This is a communication interface for receiving the transmission text encrypted by the encryption device 21 from the transmission path.

As shown in FIG. 27, the encrypted communication network for realizing the information providing service is the information providing center 1
0 and users A, B, ..., M. The information providing center 10 and each user share in advance the unique and secret keys K _A , K _B , ..., K _M. Key sharing
This can be realized by the information providing center 10 setting the key in advance. Alternatively, it can also be realized by a publicly known key sharing system as shown in the document "Cryptography and Information Security" (Tsujii and Kasahara, published in 1990, Shokosha Co., Ltd., 72-73, 97-104).

Each user of the encrypted communication network realizing the information providing service has a portable storage device 30 as shown in FIG. The portable storage device 30 stores the secret key of the owner of each portable storage device 30 required for cryptographic communication. If the secret key is known to anyone other than the owner, you cannot communicate secretly,
Since a highly reliable information providing service cannot be realized, each user has a portable storage device 30 separately from the communication terminal 20 in consideration of security so that the secret key is not known to anyone other than the owner. It has such a structure. The portable storage device 30 may be a part of the communication terminal 20 as long as a physically safe area can be secured for each user, but in that case, the communication terminal 20 that can be used for each user is You will be limited. The communication terminal 20 and the portable storage device 30 are separated from each other,
By not storing the confidential information of each user in the communication terminal 20, the user can exchange the confidential information of the user through any portable storage device 30 in any communication terminal 20. It is convenient because it can be used for encrypted communication.

This portable storage device 30 is used for the communication terminal 2
0 is capable of exchanging information with 0 via a secure communication path, and has a physically secure area as the holding means 31. Only the legitimate owner can operate the portable storage device 30 normally, and it is determined whether or not the legitimate owner by the authentication procedure such as the password. The portable storage device 30 can be realized by an IC card or the like.

The information providing center 10 is configured as shown in FIG. 3, and it is provided with the above-mentioned communication terminal 20, the database 11 in which the information to be provided is stored, the information provided and the conditions for providing the information. It has at least one billing device 12 for performing billing and a storage device 13 for storing information on secret keys and usage amounts of all users necessary for encrypted communication. In FIG. 2, a plurality of communication terminals 20 are provided to enable simultaneous provision of information to a plurality of users. If you want to build a larger-scale information provision system, use the database 1
There may be a plurality of charging devices 12, charging devices 12, and storage devices 13.

The database 11 is configured as shown in FIG. 4, and stores information to be provided to the user and fee information for the service providing the information in association with each other. The charge information is further divided into charges depending on the encryption speed at which the information is encrypted. For example, if the encryption speed can be set by the encryption speed setting device 23 as V _q1 , V _q2 , ..., V _qt , the basic charge is the charge when each information is provided at the encryption speed V _q1 . rates M _q2 times the base rate at the time of the offer in the V _q2, ..., fee at the time of the offer in the V _qt do pricing, such as that M _qt times the base rate. In addition, each information is given a name so that it can be specified by the user. Such a database 11 can be easily configured with an existing database.

The storage device 13 is configured as shown in FIG. 5, and has a key storage area in which a secret key necessary for encrypted communication is stored for each user who subscribes to the information providing network, There is a cumulative amount storage area in which the cumulative amount of the fee system for a certain period is stored. This period will be called the usage fee collection period. The usage fee collection period is set to, for example, one month. The information providing center 10 calculates a fee for the information providing service for each user within the usage fee totaling period based on the accumulated amount of money for each user in the accumulated amount of money storage area, and charges each user. After a certain usage charge total period, the usage amount for each user during the usage charge total period stored in the accumulated amount storage area is moved to other storage means as information for backup, and the accumulated amount storage area is stored. The usage amount for each user of is reset.

The charging device 12 is constructed as shown in FIG. The billing device 12 performs billing calculation on the currently provided information according to the encryption speed used at the time of providing. The billing device 12 can retrieve the charge information from the database 11. In addition, a new cumulative amount of money is calculated by adding the current information charge to the cumulative amount of money of the user who provided the information held in the storage device 13, and the new amount is newly stored in the cumulative amount storage area of the user of the storage device 13. Write the cumulative amount of money. The information providing network according to the present embodiment is configured by the above devices.

For example, the user A requests the information providing center 10 to provide certain information, the information providing center 10 sends the information to the user A, and the information providing center 10 charges the user A for the information providing service. The procedure for charging is performed as follows. Here, the user A has already been provided with information from the information providing center several times within the current usage fee collection period, and as a result, within the current usage fee collection period of the user A in the accumulated amount storage area of the storage device 13. The cumulative amount of money is Charg
Let's say it is e _A. The name of the information requested by the user A is Info. further,
The basic charge of Info (charge when provided at the encryption speed V _q1 ) is UC _Info . Further, user A is Inf
Let o be the one wishing to be provided at the encrypted rate V _qi . In addition, the charge for the information providing service at the encryption speed V _qi is M of the basic charge UC _Info depending on the amount of information and the encryption speed.
It is assumed to be _qi times. Further, the user A uses the information name Inf
It is assumed that o and its basic charge UC _Info are known in advance. Further, in the following description, it is assumed that the authorized user A is authenticated by the portable storage device 30 of the person himself / herself and the portable storage device 30 is set so as to be able to communicate with the communication terminal 20 in an operable state. . Further, it is assumed that the user A has been authenticated by the information providing center 10 as a legitimate user and is certainly A. These two authentications can be sufficiently realized by a known authentication technique.

[Pre-Procedure for Providing Information According to the Present Invention] 1. The user A requests the information providing center 10 to provide Info. At the same time, let us know that you want to provide at the encryption speed V _qi . 2. In response to a request from the user A to provide Info, the information providing center 10 charges the Info basic charge UC _Info and the information providing service at the encryption speed V _qi by M _qi times the basic charge UC _Info. Therefore, the charge for the information providing service is calculated, and the calculated charge information is sent to the user A. 3. If the user A receives the charge information and is satisfied with the charge for providing Info, the information providing center 1
0 to request Info provision. If not satisfied, the information providing center 10 is notified that the Info providing request has been canceled, and this procedure is ended.

Below, the user A sends an information to the information providing center 10.
The procedure is continued for the case of requesting provision of nfo. [Procedure of Information Providing According to the Present Invention (Regarding Information Providing Center)] The speed setting signal sets the encryption speed of the encryptor 21 to that determined in the previous procedure. 2. The secret key K _A held in the key storage area of the user A of the storage device 13 is set in the encryption device 21. 3. The encryption device 21 encrypts the data and sends it to the user A via the communication interface 22.

[Procedure for providing information according to the present invention (user A
Regarding)] 1. The speed setting signal sets the encryption speed of the encryptor 21 to that determined in the previous procedure. 2. The secret key K _A held in the portable storage device 30 is set in the encryption device 21. 3. The encrypted data is received from the transmission line via the communication interface 22, and the encryptor 22 receives the encrypted data.
Decrypt the encrypted data sent from.

Below, from the information providing center 10 to the Info
The charging procedure after the end of provision is shown. [Billing procedure according to the present invention (related to information providing center)] The charging device 12 can access the Info of the database 11
Basic charge information UC_InfoTake out the encryption speed V_qi
The fee for the information service at _InfoM
_qiRetrieve the information that it is double. 2. The charging device 12 uses the basic charge information UC_InfoAnd M_qiOr
Calculate the fee for providing information. In this case, the charge is M
_qi× UC_InfoBecomes 3. The billing device 12 stores the charges stored in the storage device 13.
Charge A of user A_ATo M_qi× UC_Info
Add a new cumulative amount Charge_A+ M_qi× UC
_InfoAnd calculates the accumulated amount of money of the user A of the storage device 13.
New accumulated amount of charge in the area_ATo + M_qi× UC
_InfoWrite. However, if you settle each time, the accumulated amount
Need not be calculated.

The information providing center 10 charges a charge to each user based on the accumulated amount of money for each user every time the above-mentioned charge collection period ends. Further, when the usage fee collection period ends, the usage amount for each user of the usage fee collection period stored in the accumulated amount storage area is moved to other storage means as information for backup to store the accumulated amount. The usage amount for each user of the area is reset.

By the above procedure, the processing speed of encryption can be selected with a high degree of freedom. Therefore, for example, when the communication terminal 20 possessed by the user is low, the charge of the information providing service is set low and the user When the communication terminal 20 has a high capability and wants to make the best use of the capability, it is possible to set a high charge for the information providing service.

The above [pre-procedure 1 for providing information according to the present invention] does not have to be performed every communication. For example, it is not necessary when the processing speed is previously discussed between the sender and the receiver and the encrypted communication is performed at the processing speed.

[Embodiment 2] In this embodiment, the information providing service is realized by using the communication terminal 20 as shown in FIG. In this embodiment, the encryption method is DE for simplicity.
Consider the S-cipher. As described above, the DES cipher is an algorithm in which the same process is repeated 16 stages, so that it is possible to repeat the process in the same circuit. For example, if the processing of one stage of the DES encryption shown in FIG. 29 is made into a circuit as one processing unit (processing unit: PE), the encryption device 21 capable of changing the processing speed can be realized.

In this embodiment, the DES encryption circuit is configured by using a plurality of circuits each having a selector at the input of each PE, so that the encryption (decryption) processing speed can be changed according to the required processing speed. The encryption device 21 is configured in the. FIG. 8 shows an example of the encryption device 21 that varies the processing speed according to the present invention. The encryptor 21 of FIG. 8 has two PEs 21a (PE3, PE4) and two selectors 21b each having a processing circuit for one stage of the DES encryption shown in FIG.
(Selector 3, selector 4). The selector 21b is controlled by the speed setting signal.

When it is desired to operate the encryption device 21 at high speed, the encryption processing is performed using both of the two PEs 21a. That is, at the start of the calculation, the selector 3 outputs the signal 3
a, the selector 4 selects the signal 4b, and thereafter, the selector 3 selects the signal 3b, and PE3 and PE4 are repeatedly used eight times each.

When it is desired to operate the encryptor 21 at a low speed, the encryption process is performed by using one PE 21a (PE4). That is, at the start of calculation, the selector 4 outputs the signal 4
a is selected, and thereafter, the selector 4 selects the signal 4c, and the PE 4 is repeatedly used 16 times. At this time, the selector 3 and PE3 are not used. In this case, PE21
The time required for the DES encryption processing is almost twice as long as when two a's are used, and the processing speed becomes almost half.

In particular, this encryption device 21 is installed in the information providing center 10
When it is used in the communication terminal 20, the PE3 and PE4 can perform encryption for different users with different keys when operating at low speed. That is, the selector 3 selects the signal 3a and the selector 4 selects the signal 4a at the start of the calculation, and thereafter, the selector 3 selects the signal 3c and the selector 4 selects the signal 4c, and PE3 and PE4 are used 16 times each. At this time, PE3 and PE4
By setting keys for different users in and, it is possible to obtain ciphertexts for different users and to provide information to different users.

That is, by constructing the encryption device 21 by using a plurality of the PEs 21a and determining the processing path according to the required processing speed, it is possible to realize the encryption device 21 whose processing speed can be changed. Although FIG. 8 shows the case where two PEs 21a are used, the number of PEs used in the present invention is not particularly limited.

The communication interface 22 may be the same as that used in the first embodiment. Further, as the cryptographic communication network for realizing the information providing service, the one shown in FIG. 27 is used. Also in this embodiment, the procedure of communication and billing between the information providing center 10 and the user is the same as the procedure shown in the first embodiment.

[Embodiment 3] In this embodiment, DES encryption is considered as an encryption method for simplification, and a communication terminal 20 as shown in FIG. 7 equipped with an encryptor 21 shown in FIG. 9 is used. Information service is realized. The encryptor 21 of FIG.
Is composed of one PE 21a (PE5) and one selector (selector 5) 21b configured to perform the processing of one stage of DES encryption. The selector 21b is controlled by the speed setting signal.

Cryptographic communication with a high cryptographic strength using the encryptor 21 is realized by performing the encryption process using the PE 5 many times. That is, the selector 5 selects the signal 5a at the start of the calculation, and thereafter the selector 5 selects the signal 5b, and the PE 5 is repeatedly used until the desired intensity is obtained. For example, since the DES encryption performs 16 steps of processing, PE5 may be repeatedly used 16 times or more when it is desired to have a higher strength than the DES encryption. However, the encryption processing speed decreases in inverse proportion to the number of times the PE 5 is repeatedly used.

Further, the encrypted communication with the low encryption strength using the encryptor 21 is realized by reducing the number of times the PE 5 is used and performing the encryption processing. However, the encryption processing speed increases as the number of times the PE 5 is repeatedly used is reduced. For example, the DES cryptography performs 16 rounds of processing, so if you want to lower the strength than the DES cryptography, set PE5
It may be used repeatedly 6 times or less. In this case, the encryption can be performed at a processing speed higher than that of the normal DES encryption. That is, the encryption strength and the processing speed thereof can be changed by the speed setting signal 5 controlling the selector 5.

Although FIG. 9 shows the case where one PE 21a is used, the number of PEs is not particularly limited.
Further, the same communication interface 22 as that of the first embodiment can be used, and an encryption communication network shown in FIG.
Use Also, in this embodiment, the information providing center 1
The communication between 0 and the user and the procedure for charging are described in the first embodiment.
The procedure is similar to. According to the present embodiment, it is possible to perform the encrypted communication between the information providing center 10 and the user, in which the encryption strength of the communication terminal 20 and the information providing fee can be selected.

[Embodiment 4] In this embodiment, as shown in FIG. 14, a communication terminal 20 having a pseudo random number generator capable of setting a pseudo random number generation speed by a generation speed setting device 24 is provided. Uses encrypted communication. As shown in FIG. 10, the pseudo random number generator 25 of this embodiment can set the pseudo random number generation speed by the generation speed setting device 24. This is realized by, for example, preparing a plurality of clocks having different frequencies as the clocks for operating the pseudo random number generator 25, and selecting the operation clock from the clocks according to the setting of the pseudo random number generation speed from the outside. it can.

FIG. 11 shows a production speed setting device 2 according to the present invention.
4 shows an example. The generation speed setting device 24 of FIG. 11 is composed of u clock generators 24a and selectors 24b. CK _{ri of the} clock generator 24a generates a clock signal r _i . The clock signals r ₁ , r ₂ , ..., R _u generated by each clock generator 24 a are the selector 2
4b, and one is selected by the information providing center 10 and the user who use the communication terminal 20. The selector 24b is controlled by the speed setting signal.

The algorithm for generating a pseudo random number sequence used in this embodiment is not particularly limited, and any algorithm can be used. Here, a description will be given of a case where a computationally safe pseudo-random number sequence generation algorithm is used as an algorithm for generating a pseudo-random number sequence, particularly a case where a square type pseudo-random number sequence is used among them.

The square type pseudo random number sequence is a pseudo random number sequence b ₁ , b ₂ , ... Generated by the following procedure. [Square type pseudo-random number sequence] p, q is p≡q≡3 (mod
4) is a prime number, N = p · q, and an initial value x
₀ (integer of 1 <x ₀ <N−1) and recursive expression x _{i + 1} = x _i ² modN (i = 0, 1, 2, ...) (1) b _i = lsb _j (x _i ) (I = 1, 2, ...) ... The bit sequence b ₁ , b ₂ , ... Obtained by (2) is called a square-type pseudo-random number sequence. However, lsb _j (x _i ) represents the lower j bits of x _i , where j is the number of bits of N.
= O (log ₂ n).

The square type pseudo-random number sequence is a computationally secure pseudo-random number sequence under the assumption that the problem of determination of the residual modularity in the modulus N is difficult in terms of computational complexity. In order to make the square-type pseudo-random number sufficiently safe, it is desirable that the number of bits n of the modulus N of the square operation expression (1) be about 512 bits. Further, the keys (initial values of the pseudo-random number generator) K _A , K _B , ... That are secretly shared in advance between the information providing center 10 and the users are 1 <K _A , K _B , ... <N. -1.

Pseudo random for generating this square type pseudo random number sequence
The number generator 25 is shown in FIG. Pseudo-random number generation of Figure 12
The generator 25 is a processing unit that performs the feedback calculation of Expression (1).
From the path 25g and the processing circuit 25h that performs the calculation of the equation (2)
The operation of the pseudo random number generator 25 is configured as follows.
You. 1. Initial value x₀Is input to the pseudo random number generator. 2. From equation (1), x₁, X_Two, ..., x_iGenerate
You. 3. The generated x₁, X_Two, ..., x_iOn the other hand, equation (2)
And obtained b ₁, B_Two, ..., b_iIs a pseudo-random number
And output.

By using the pseudo-random number generator 25 as described above, it is possible to construct an encryption device whose processing speed can be set as shown in FIG. The encryption method implemented by the encryption device 21 in this embodiment is a stream encryption method, and the encryption device 21 of FIG. 13 is composed of a pseudo random number generator 25 and an exclusive OR circuit 26.

When encryption is performed using this encryption device 21, encryption is performed by taking the bitwise exclusive OR of the input plaintext and the pseudorandom number sequence generated by the pseudorandom number generator 25. The sentence is obtained. When performing decryption, the plaintext is obtained by taking the bitwise exclusive OR of the input ciphertext and the pseudorandom number sequence (the same sequence as when encrypted) generated by the pseudorandom number generator 25. can get.

The communication interface 22 is used in the first embodiment.
27 is used as a cryptographic communication network using the same as
Use When using the stream cipher, the key shared in advance with the communication partner is used as an initial value for pseudo-random number sequence generation. The communication and billing procedures are the same as those in the first embodiment.

[Embodiment 5] This embodiment also uses the communication terminal 20 equipped with a pseudo random number generator capable of setting the pseudo random number generation speed by the generation speed setting device 24. An encryptor 21 using the pseudo random number generator 25 in this embodiment is shown in FIG. In the present embodiment, FIG.
Cryptographic communication is performed using the communication terminal 20 shown in FIG.

The pseudo random number generator 25 of this embodiment can set the generation rate from the outside. For example, the pseudo-random number generator 25 is referred to as a document “Montgomery modular exponentiation method suitable for power modular exponentiation and a systolic array that realizes it” (Megumi Iwamura, Tsutomu Matsumoto, Hideki Imai, Theological theory (A)). , Vo 1.76, No. 8, pp. 1214-1.
223, 1993. ) Can be realized by configuring as shown in FIG. In this method, the pseudo random number generator 25
Is realized by iterative processing by an arithmetic element (processing element: PE) 27 as shown in FIG. 15, and a small-scale circuit (low-speed processing) according to the number of PEs used.
It has been shown that it can be realized to a large-scale circuit (high-speed processing). The PE 27 shown in FIG. 15 is configured as shown in FIG. 16, and includes a register indicated by R1, R2, ..., R9, an adder 27a, and a multiplier 27b.

Therefore, by arranging the pseudo random number generator 25 in advance so as to repeatedly perform processing with a plurality of PEs 27, for example, when all of the PEs 27 are operated, pseudo random number generation can be performed at high speed, and When some PEs 27 are operated, pseudo random number generation can be performed at low speed.

FIG. 19 shows an example of the pseudo random number generator 25 capable of varying the processing speed according to the present invention. The pseudo random number generator 25 shown in FIG.
1, PE2) and two selectors (selector 1, selector 2). The selector is controlled by the speed setting signal.

When it is desired to operate the pseudo random number generator 25 at high speed, both PE 25a are used to generate a pseudo random number. That is, the signal 1a is selected by the selector 1 and the signal 2b is selected by the selector 2 at the start of the operation, and thereafter, the signal 1b is selected by the selector 1 and PE1 and PE2 are repeatedly used as many times as necessary for the square type operation.

When it is desired to operate the pseudo random number generator 25 at a low speed, one PE 25a (PE2) is used to generate a pseudo random number. That is, the selector 2 selects the signal 2a at the start of calculation, and the selector 2 thereafter selects the signal 2c.
And PE2 is repeatedly used as necessary for the square type operation. Selector 1 and PE1 are not used. In this case, the time required for the squaring operation is almost twice as long as when two PEs 25a are used, and the generation speed is almost half.

In particular, this encryption device 21 is installed in the information providing center 10
When the communication terminal 20 is used for low speed operation, PE1 and PE2 can perform encryption for different users with different keys. That is, when the operation is started, the selector 1 selects the signal 1a, the selector 2 selects the signal 2a, and thereafter, the selector 1 selects the signal 1c and the selector 2 selects the signal 2c. Use as many times as you want. At this time, by setting keys for different communication partners in PE1 and PE2, ciphertexts addressed to different users can be obtained.

That is, by constructing the pseudo random number generator 25 using a plurality of the PEs 25a and determining the processing route according to the required processing speed, the pseudo random number generator 25 capable of changing the processing speed can be realized. . In FIG. 19, PE2
The case where two 5a are used is shown, but the number is not particularly limited.

The communication interface 22 used is the same as that of the first embodiment, and the encryption communication network shown in FIG. 27 is used. The communication and billing procedures are also performed in the same manner as in the first embodiment.

[Embodiment 6] This embodiment also uses the communication terminal 20 provided with the pseudo-random number generator 25 whose pseudo-random number generation speed can be set by the generation speed setting device 24. In the fourth and fifth embodiments, since the key shared between the information providing center 10 and the user is fixed, the initial value of the pseudo random number generator 25 is always the same value when the user is the same, and the same. There is a problem that a pseudo-random number sequence is generated.

Therefore, in this embodiment, it is possible to improve the security by changing the initial value of the pseudo-random number generator 25 every time the user is the same. Example 4
In equations (1) and (2), which are the procedure for generating the pseudo-random number shown in (1), x _{i + 1} that is successively updated by the feedback calculation is called an internal variable of the pseudo-random number generator 25.

The pseudo random number generator 25 of this embodiment is shown in FIG.
Processing circuit 25c for performing the feedback calculation of equation (1) and processing circuit 25d for performing the calculation of equation (2) as shown in FIG.
In addition, the internal variables updated by the calculation of the equation (1) can be read. In the case of the communication terminal 20 on the user side, the read internal variables are
It is stored in the holding means 31 of the portable storage device 30 of FIG. Further, in the case of the communication terminal 20 on the side of the information providing center 10, it is stored in the key storage area of the storage device 13.

In the fourth and fifth embodiments, the data is moved in one direction only by setting the initial value in the pseudo random number generator 25, but in the present embodiment, the internal variables of the pseudo random number generator 25 are read in the opposite direction. You can do it. The read internal variable is replaced with the common key used for the current cryptographic communication as the common key used for the cryptographic communication in the next information providing service.

By replacing the pseudo-random number generator 25 with the pseudo-random number generator 25 shown in FIG. 13 or 17, the processing speed can be varied and the encryption value can be changed each time the initial value of the pseudo-random number generator 25 is used. Can be configured. Further, the encryption terminal 21 can be used to configure the communication terminal 20 of FIG. 14 or FIG.

Also in this embodiment, the cryptographic communication network for realizing the information providing service is as shown in FIG. The communication and billing procedures are the same as those in the first embodiment. However, in [Procedure of providing information according to the present invention], the information providing center 10 side "in order to cryptographically communicate the value of the internal variable of the pseudo random number generator 25 when the encryption of the information to be provided is completed with A next time. The procedure "Keep secretly in the key storage area of the storage device 13 as a new initial value of" is required at the end, and on the user side, the "random number generator 25 of the pseudo-random number generator 25 when the decryption of the encrypted information is completed" is required. The procedure of "keeping the value of the internal variable secretly in the holding means 31 of the portable storage device 30 as a new initial value for cryptographic communication when information is provided next time" is required.

[Embodiment 7] In this embodiment, Embodiment 4,
An encryptor that uses the pseudo-random number sequence generated by the pseudo-random number generator 25 whose processing speed can be set as described in 5 and 6 as a key sequence of a block cipher whose processing speed can be set as shown in FIG. The communication terminal 20 including the terminal 21 is used.

First, the encryptor 21 that uses a pseudo-random number sequence as a key sequence for block encryption will be described. DES
(Data Encryption Standard
d) Encryption and FEAL (Fast data Enci)
The algorithm open type common key block cipher represented by the hermage ALgorithm) has a drawback that the key can be analyzed when the number of pairs of ciphertext and plaintext by the same key is output more than a certain number. To eliminate this drawback, the key is updated at any time by a computationally secure pseudo-random number before outputting the number of ciphertext and plaintext pairs required for analysis as shown in FIG. 22, which makes the key analysis difficult. By doing so, an encryption method that makes it difficult to analyze the key of the block cipher with respect to the algorithm public type common key block cipher is considered. (References: Yamamoto, Iwamura, Matsumoto, Imai; "Practical Cryptographic Method Using Squared Pseudo Random Number Generator and Block Cipher", IEICE Technical Report, SEC93-29, 1993-08,).

A computationally safe pseudo-random number sequence means that if there is a polynomial-time algorithm that predicts a subsequent pseudo-random number sequence from a part of the pseudo-random number sequence, it will be computationally difficult to use. It refers to a pseudo-random number sequence that has been proved to be capable of constructing a polynomial time algorithm for the so-called problem. That is, the computationally secure pseudo-random number sequence is a sequence in which it is extremely difficult to predict subsequent sequences from the output sequence in terms of computational complexity. This is C. Yao, “Theory and Appl
ications of Trapdoor Func
conditions "Proceedings of the"
23rd IEEE Symposium on Fo
foundations of Computer Sci
ence, IEEE, pp. 80-91, 1982. Alternatively, M. Blum and S. Micali, “H
ow to GENERATE CRYPTOGRAP
physically Stronge Sequences
of Pseudo-Random Bits. "Pr
oc. 22nd FOCS, IEEE, pp. 112-
117, 1982, and the like. An algorithm for generating a computationally secure pseudo-random number is as shown in the document "Cryptography and Information Security" (Tsujii, Kasahara, 1990, Shokosha, Ltd., 86). A method using square type random numbers, RSA encryption, discrete logarithm, and reciprocal encryption is known.

FIG. 22 shows a cryptographic device, which comprises a pseudo-random number generator 25, an arithmetic unit 40 and a block cipher 21. As the algorithm of the block cipher 21, a block cipher such as DES cipher or FEAL cipher is used. The block cipher 21 encrypts plaintext and decrypts ciphertext. The pseudo random number generator 25 generates a pseudo random number according to a computationally secure pseudo random number generation algorithm. Generally, computationally safe pseudo-random number sequences b ₁ , b
₂ , ... Are generated from the initial value x ₀ according to the following equation. x _{i + 1} = f (x _i ) (i = 0,1, ...) (3) b _{i + 1} = g (x _{i + 1} ) (i = 0,1, ...) 4)

The pseudo random number generator 25 is shown in FIG.
Circuit for performing feedback calculation of equation (3)
25e and a processing circuit 25f for performing the calculation of the equation (4).
Is done. Therefore, the operation of the pseudo random number generator 25 is as follows.
Become like 1. Initial value x₀Is input to the pseudo random number generator 25. 2. From equation (3), x₁, X_Two, ..., x_iGenerate
You. 3. The generated x₁, X_Two, ..., x_iOn the other hand, equation (4)
And obtained b ₁, B_Two, ..., b_iIs a pseudo-random number
And output.

Further, the arithmetic unit 40 of FIG. 22 converts the obtained b ₁ , b ₂ , ..., B _i into a block cipher key sequence. Each block cipher key is a bit string having a length determined by the block cipher algorithm to be used, and the arithmetic unit 40 is, for example, a computationally secure pseudo-random number sequence b ₁ ,
It is generated by dividing b ₂ , ..., B _i for each bit length.

In FIG. 22, M _uv (u = 1, 2, ...,
t; v = 1, 2, ..., S) is a plaintext block and k _u (u
= 1, 2, ..., t) is the block cipher key, k
_u (M _uv ) (u = 1, 2, ..., T; v = 1, 2, ...,
s) shows a ciphertext block obtained by encrypting the plaintext block M _uv with the cipher key k _u . Where M _u1 to M
The s blocks up to _us are encrypted with the same key k _u . The plaintext block in FIG. 22 is encrypted by a plurality of encryption keys by sequentially using the key sequences k ₁ , k ₂ , ... That are updated by the pseudo random number generator 25 and the arithmetic unit 40 as the keys of the block cipher. It With the above encryption method, it is possible to limit the number of plaintext blocks encrypted with the same key, which makes it difficult to analyze the key.

In the above encryption method, the number s of blocks encrypted with the same key is determined depending on the encryption processing speed of the block cipher and the key generation speed. Therefore, when the key generation speed is constant, if the encryption (decryption) processing speed of the block cipher is slow, s becomes small and the security increases. On the contrary, if the encryption (decryption) processing speed of the block cipher is high, the practicality is increased, but s is increased and the security is lowered. Also,
When the encryption (decryption) processing speed of block cipher is constant,
If the key generation speed can be increased, s can be reduced, and the security can be improved. On the contrary, if the key generation speed can be reduced, it is possible to simplify s by making s larger and lowering the security. Furthermore, if both the encryption (decryption) processing speed of the block cipher and the key generation speed are variable, encrypted communication with more flexibility and more flexibility in the trade-off between processing complexity and security is possible. Becomes

Therefore, if this encryption method is adopted as the encryption method used for the information providing service, the charge of the information providing service varies depending on how safe the information requested by the user of the information providing service is sent. It is possible to realize a charge system that can be applied. In other words, in order to provide information with high security, it is necessary to increase the key generation speed, so considering the load on the pseudo-random number generator 25 for that amount, the fee for the information providing service is set high. When information is provided with low security, a high key generation rate is not required, and thus a fee system for setting the fee for the information providing service low is possible.

The above-mentioned encryption method is a pseudo random number generator 25 capable of setting the processing speed described in the fourth, fifth and sixth embodiments, and an encryption capable of setting the processing speed described in the first, second and third embodiments. It can be configured by any combination with the device 21.

Here, in particular, the pseudo random number sequence generated by the pseudo random number generator 25 capable of setting the processing speed described in the fourth embodiment is changed to the encryption device 21 capable of setting the processing speed described in the first embodiment. The case of using as a key sequence of will be described. In this embodiment, as shown in FIG. 21, an encryption device 21 that performs encryption (and decryption) according to an algorithm determined by the network, and a pseudo random number that is computationally secure according to the algorithm determined by the network is generated. Pseudo-random number generator 25, a calculator 40 that converts the pseudo-random number output from the pseudo-random number generator 25 into a key sequence of the encryptor 21, a communication interface 22, an encryption speed setting device 23, and a generation speed setting device And a communication terminal 2 including 24
0 is used.

As the encryption speed setting device 23, the one shown in FIG. 2 in the first embodiment is used. Thereby, the encryption device 21 can set the processing speed from the outside. As the generation speed setting device 24, the one shown in FIG. 11 is used. This allows the pseudo random number generator 25 to set the processing speed from the outside. The arithmetic unit 40 also converts the pseudo-random number sequence output from the pseudo-random number generator 25 into a key string for the encryptor 21. Therefore, it is necessary to change the processing speed of the arithmetic unit in proportion to the processing speed of the pseudo random number generator 25. Therefore, the clock signal selected by the generation speed setting device 24 also changes the processing speed of the arithmetic unit 40. Also,
The flexibility is further expanded by the selective combination of the clocks of both the encryption speed setting device 23 and the generation speed setting device 24.

The communication interface 22 is used in the first embodiment.
27 is used, and the encryption communication network shown in FIG. 27 is used. The communication and billing procedures are the same as those in the first embodiment.

The encrypted communication between the information providing center 10 and the user according to the present invention is performed by the following procedure. The pre-procedure is the same as in Example 1. However, in the previous procedure, “information that specifies the encryption speed of the encryption device 21 and the processing speed of the pseudo-random number generator 25” is used instead of “information that specifies the encryption speed of the encryption device 21” via the communication interface 22. The difference is that they are sent. Continue the procedure below.

[Procedure of Information Provision by the Present Invention (Regarding Information Provision Center)] 1. The encryptor 21 and the pseudo random number generator 2 depending on the speed setting signal
Set the processing speed of 5 to the one determined in the previous procedure. 2. The pseudo-random number generator 25 sets the secret key K _A held in the key storage area of the user A of the storage device 13 as the initial value x _0.
Set to. 3. The pseudo-random number generator 25 is operated to generate a pseudo-random number sequence that is computationally safe. 4. The pseudo random number sequence generated by the arithmetic unit 40 is used by the encryption unit 2
Convert to a key sequence of 1. 5. The key string output from the arithmetic unit 40 is updated and used as the key of the encryptor 21, and the encryptor 21 encrypts the data and transmits it to the user A via the communication interface 22.

[Procedure for providing information according to the present invention (user A
Regarding)] 1. The encryptor 21 and the pseudo random number generator 2 depending on the speed setting signal
Set the processing speed of 5 to the one determined in the previous procedure. 2. The secret key K _A held in the portable storage device 30 is set in the pseudo random number generator 25 as an initial value x ₀ . 3. The pseudo-random number generator 25 is operated to generate a pseudo-random number sequence that is computationally safe. 4. The pseudo random number sequence generated by the arithmetic unit 40 is used by the encryption unit 2
Convert to a key sequence of 1. 5. The encrypted data is received from the transmission path via the communication interface 22, and the key string output from the arithmetic unit 40 is used as the key of the encryptor 21 while being updated and sent from the information providing center 10 by the encryptor 21. Decrypt encrypted data.

With the above procedure, it is possible to select the tradeoff between encryption security and processing speed with a high degree of freedom, and thus it becomes possible to set the charge of the information providing service according to the security of encryption and the processing speed load. However, when the pseudo-random number generator 25 shown in the sixth embodiment is used, both of the user and the information providing center 10 are asked to "pseudo-random number generator when decryption of encrypted data is completed" in the encrypted communication procedure. The procedure of "keeping the value of the internal variable of 25 in secret in the portable storage device 30 or the storage means as a new initial value for the encrypted communication of the next information providing service" is finally required.

In the present embodiment, the encryption device 21 is D
Although the one that performs ES encryption was used, it is not limited to DES encryption,
Any common key encryption can be used, for example:
FEAL encryption can also be used. In addition, the encryption device 21
Uses one DES encryption device, but a plurality of DES encryption devices may be used, or DES encryption and FEAL encryption may be combined. Furthermore, although a square-type pseudo-random number is used as the algorithm of the computationally secure pseudo-random number generator 25, any computationally secure pseudo-random number generation algorithm can be used. For example, the above-mentioned document "Cryptography and Information Security" (Tsujii and Kasahara, 1
As described in 1986, published by Shokosha Co., Ltd., item 86), RSA cryptography, discrete logarithm, and reciprocal cryptography can also be used in the algorithm of pseudo-random number generation of the present invention.

[Embodiment 8] In Embodiment 7, Embodiment 4,
For communication using the pseudo random number generator 25 capable of setting the processing speed described in 5 and 6 and the encryption device 21 in which the block cipher capable of setting the processing speed described in the first, second and third embodiments is combined. Although the information providing service using the terminal 20 has been described, the encryption realized by combining the pseudo random number generator 25 capable of setting the processing speed described in the fourth, fifth and sixth embodiments and the block cipher having a constant processing speed. The method, the block cipher whose processing speed can be set as described in the first, second, and third embodiments, and the pseudo-random number generator 25 with a constant processing speed.
The present invention also includes an encryption method realized by a combination with.

Here, in particular, a case will be described in which the pseudo-random number sequence generated by the pseudo-random number generator 25 having a constant processing speed is used as the key sequence of the encryption device 21 capable of setting the processing speed described in the first embodiment. . In this embodiment, FIG.
An encryption device 21 that performs encryption (and decryption) according to an algorithm determined by the network, as shown in FIG.
And a pseudo-random number generator 25 that generates a computationally secure pseudo-random number according to an algorithm determined by the network.
A communication terminal 20 including a calculator 40 for converting the pseudo random number output from the pseudo random number generator 25 into a key string of the encryption device 21, a communication interface 22, and an encryption speed setting device 23 is used. As the encryption speed setting device 23, the one shown in FIG. 2 in the first embodiment is used. Thereby, the encryption device 21 can set the processing speed from the outside. The communication interface 22 is the same as that of the first embodiment, and the encryption communication network shown in FIG. 27 is used.

The encrypted communication for providing information between the information providing center and the user A is performed by the same procedure as the procedure shown in the seventh embodiment. However, in the pre-procedure, only "information indicating the processing speed of the encryption device 21" is exchanged via the communication interface 22 instead of "information indicating the processing speed of the encryption device 21 and the processing speed of the pseudo random number generator 25". The point is different.

[Embodiment 9] In Embodiment 7, the encryption speed setting device 23 of FIG. 2 and the generation speed setting device 24 of FIG. 11 were considered as independent devices, but as shown in FIG. It is also possible to provide an information providing service as the speed setting device 28. The speed setting device 28 of FIG. 25 includes v clock generators 28a and selectors 28b. CK _{pi of the} clock generator 28a generates a clock signal p _i . The clock signals p ₁ , p ₂ , ..., P _v generated by each clock generator 28a are input to the selector. There are two outputs of the selector 28b, one of which is used as the operation clock of the encryption device 21, and the other of which is used as the operation clocks of the pseudo random number generator 25 and the calculator 40. The selector 28b is controlled by the information providing center 10 and the user who use the communication terminal 20 according to the speed setting signal,
Two of the three inputs are selected.

[0094]

As described above, according to the present invention, the cryptographic processing speed and the cryptographic strength can be selected, and the fee is charged according to the selected cryptographic processing speed and the cryptographic strength. It is possible to select the security of encryption and its service charge when providing information that has not been considered, or the speed of encryption and its service charge, and obtain a highly flexible fee structure for information providing services. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a communication terminal according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an encryption speed setting device of the encryption device according to the first exemplary embodiment of the present invention.

FIG. 3 is a block diagram of an information providing center according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a database according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a storage device according to a first embodiment of the present invention.

FIG. 6 is a block diagram of a charging device according to the first embodiment of the present invention.

FIG. 7 is a block diagram of a communication terminal according to Embodiments 2 and 3 of the present invention.

FIG. 8 is a block diagram of an encryption device capable of setting an encryption speed according to a second embodiment of the present invention.

FIG. 9 is a block diagram of an encryption device capable of setting an encryption strength and a processing speed according to a third embodiment of the present invention.

FIG. 10 is a block diagram of a pseudo random number generator capable of setting a processing speed by a generation speed setting device according to a fourth embodiment of the present invention.

FIG. 11 is a block diagram of a generation rate setting device according to examples 4 and 7 of the present invention.

FIG. 12 is a block diagram of a square type pseudo random number generator according to a fourth exemplary embodiment of the present invention.

FIG. 13 is a block diagram of an encryption device capable of setting an encryption speed according to Examples 4 and 6 of the present invention.

FIG. 14 is a block diagram of a communication terminal according to a fourth embodiment of the present invention.

FIG. 15 is a block diagram of a pseudo random number generator using PE according to a fifth embodiment of the present invention.

FIG. 16 is a block diagram showing a configuration of PE.

FIG. 17 is a block diagram of an encryption device capable of setting an encryption speed according to embodiments 5 and 6 of the present invention.

FIG. 18 is a block diagram of a communication terminal according to a fifth embodiment of the present invention.

FIG. 19 is a block diagram of a pseudo random number generator capable of setting a generation rate according to a fifth embodiment of the present invention.

FIG. 20 is a block diagram of a square type pseudo random number generator according to Example 6 of the present invention.

FIG. 21 is a block diagram of a communication terminal according to a seventh embodiment of the present invention.

FIG. 22 is a block diagram of an apparatus that performs an encryption method for updating a key at any time.

FIG. 23 is a block diagram of a pseudo random number generator according to Embodiment 7 of the present invention.

FIG. 24 is a block diagram of a communication terminal according to an eighth embodiment of the present invention.

FIG. 25 is a block diagram of a speed setting device according to a ninth embodiment of the present invention.

FIG. 26 is a block diagram of a portable storage device used in each embodiment of the present invention.

FIG. 27 is a block diagram of a cryptographic communication network that realizes an information providing service.

FIG. 28 is a block diagram of a conventional communication terminal.

[Fig. 29] Fig. 29 is a block diagram illustrating processing of a one-step sentence of DES encryption.

[Explanation of symbols]

 10 Information Providing Center 11 Database 12 Charging Device 13 Storage Device 20 Communication Terminal 21 Cryptographic Device 23 Encryption Speed Setting Device 24 Generation Speed Setting Device 25 Pseudo Random Number Generator 28 Speed Setting Device

Claims (8)

[Claims] 1. An encryption transmission means for encrypting and transmitting data, a selection means for selecting an encryption processing speed in the encryption transmission means, and a charging means for charging according to the encryption processing speed selected by the selection means. A cryptographic communication device equipped with. 2. The encryption transmission means has a common secret key unique to both means and a decryption reception means on the receiving side, and performs an encryption process according to a predetermined algorithm and a predetermined operation. A pseudo-random number generator that generates a pseudo-random number sequence by performing the operation, and an arithmetic unit that converts the pseudo-random number sequence output from the pseudo-random number generator into a key sequence of the encryption device, wherein the selection means is the encryption device. A processing speed and / or a generation speed of the pseudo-random number sequence are selected, and the charging means charges according to the encryption processing speed and / or generation speed selected by the selection means. Item 1. The encrypted communication device according to item 1. 3. The cryptographic communication device according to claim 2, wherein a pseudo random number sequence that is computationally secure is used as the pseudo random number sequence generated by the pseudo random number generator. 4. The cryptographic communication device according to claim 2, wherein a square type pseudo random number generator is used as the pseudo random number generator. 5. The cryptographic communication device according to claim 1, wherein the selecting means is a clock selecting means that can select an arbitrary clock from a plurality of clocks having different frequencies. 6. A plurality of processing means for performing a repetitive processing part in the processing performed by the encryption device and / or the pseudo-random number generator, and the selection means selects the number of use of the plurality of processing means. The cryptographic communication device according to claim 2, wherein 7. The cipher according to claim 2, further comprising a processing means for performing a repetitive processing part in the processing performed by the encryption device, and the selecting means selects the number of times the processing means is used. Communication device. 8. A cryptographic communication system capable of variably setting encryption strength while communicating encrypted data via a network, wherein the data transmission side responds to the data reception side according to the encryption strength. An encrypted communication system characterized by charging.