JP5997588B2 - COMMUNICATION SYSTEM, COMMUNICATION METHOD, COMMUNICATION DEVICE, AND COMMUNICATION PROGRAM - Google Patents

Description

  The present invention relates to a communication system, a communication method, a communication apparatus, and a communication program.

  When a mobile phone, a tablet PC (Personal Computer), and other terminal devices receive provision of various services via a network, authentication via the network may be performed. In this authentication, the terminal device transmits the encrypted authentication information to a server (authentication server) that performs authentication, and the authentication server decrypts the received authentication information. Then, the authentication server determines whether or not the information registered in advance matches the decrypted information, and permits the provision of the service when the information matches.

  If the authentication information is valid for a certain period of time, a third party may intercept the authentication information and analyze the authentication information by trial and error. On the other hand, an invention of an authentication method that changes each time it is used and performs authentication using a one-time password that is authentication information that is valid only once is disclosed (for example, see Patent Document 1). In this authentication method, time synchronization is performed between communicating devices, and a one-time password obtained by encrypting the time with an irreversible algorithm is transmitted as authentication information.

  Incidentally, an application (application program) for using the service may be installed in the terminal device. In this case, there are increasing cases in which cryptographic processing calculation procedures for authentication and key generation procedures are described in an application. On the other hand, an analyst (attacker) can read an application including a key generation procedure, store it in another computer device or the like, and analyze the key generation procedure by reverse engineering. Here, even if the key generation procedure has been analyzed and the analyst has tampered with the app and tried to receive a service illegally, a mechanism that does not operate normally when tampering is detected is embedded in the app. If this is the case, the app is unlikely to work properly. However, if an application is created by a method of assembling a calculation procedure from scratch (referred to as a scratch) without reusing a legitimate application code, the service may be used illegally.

  On the other hand, the invention of the method of communicating by a common key encryption system is disclosed (for example, refer patent document 2). In this method, the first device that performs communication selects an arbitrary fixed key from the fixed key table and generates a new common key by applying a predetermined calculation process. The first device uses the generated common key for encryption and transmits the index information of the fixed key to the second device. The second device includes the same fixed key table as the first device, and selects the fixed key from the fixed key table using the received index information and adds a predetermined calculation to the first device. The same common key is generated and used for decryption.

  Further, an invention of a method for obtaining an encryption key using an algorithm selected based on the identifier of the own device and the identifier of the communication partner is disclosed (for example, see Patent Document 3).

  According to the methods described in Patent Documents 2 and 3, since the key generation procedure is changed by the index information and the identifier, the analyst performs the key by reverse engineering as compared with the case where the key is generated by the same procedure every time. It is difficult to analyze the generation procedure.

JP 2008-1981147 A JP 2012-147341 A Japanese Patent Laid-Open No. 11-032034

  However, in the method described in Patent Literature 1, the authentication information generation procedure may be analyzed. As a result, the method described in Patent Document 1 may not provide sufficient security.

  In addition, if the method described in Patent Document 2 is to have the property of a one-time password (one-time property), it is necessary to change the fixed key to be selected for each communication. In this case, it is necessary to transmit the index information of the fixed key every time encrypted communication is performed, and the amount of communication increases. An increase in the amount of communication leads to an increase in communication costs (communication costs) such as an increase in communication charges, an increase in power consumption, and a consumption of communication bandwidth. Further, when the index information of the fixed key is intercepted, if the communication subject has the same fixed key table, it is possible to perform unauthorized access even if it is not the original communication subject. Therefore, the method described in Patent Document 2 may not provide sufficient security.

  In the method described in Patent Document 3, for example, when communicating with the same communication partner many times, the identifier of the communication subject does not change, so it is difficult to provide a one-time property. Even when communicating with different parties, as in the method described in Patent Document 2, it is necessary to transmit identifiers for each encrypted communication, which increases communication costs and provides sufficient security. It may not be possible.

  As described above, in the conventional communication system and communication method, it is difficult to improve the security while suppressing the communication cost.

  The present invention has been made in view of such circumstances, and an object of the present invention is to improve security while suppressing communication costs.

One embodiment of the present invention is a communication system including a first communication device and a second communication device, wherein the first communication device is configured to perform a plurality of different calculation procedures from the own device and the second communication device. A first communication device-side key generation unit that generates key data by a process including selecting one or more calculation procedures based on a time obtained by rounding a fraction less than a common time with a communication device; An encryption unit that encrypts data using the key data generated by the first communication device-side key generation unit; and a transmission unit that transmits the encrypted data to the second communication device. The second communication device includes a receiving unit that receives the encrypted data from the first communication device, and a plurality of calculation procedures based on a fractional processing time less than the common time. Selecting one or more calculation procedures from A second communication apparatus key generation unit, the second decoder which decodes the encrypted data by using the key data generated by the communication apparatus-side key generating unit for generating key data by processing, An authentication unit that performs authentication by determining whether or not the decrypted data matches the predetermined data, and in the determination by the authentication unit, the decrypted data does not match the predetermined data In this case, the second communication device side key generation unit selects one or more calculation procedures from the plurality of calculation procedures based on a time obtained by shifting a fractional processing time less than the common time by a predetermined amount. And generating the key data generated by the process including the step of using the key data generated by the process including selecting one or more calculation procedures based on the time shifted by the predetermined amount. Te, determines data decoded by said decoding unit again whether matches a predetermined data is a communication system.

Further, according to another aspect of the present invention, the plurality of different calculation procedures may include a calculation procedure having a different combination of logical operations, a calculation procedure having a different number of repeated operations, or a combination of logical operations. Is a communication system in which the calculation procedures are different from each other and the number of repeated calculations is different from each other.
Further, according to another aspect of the present invention, the first communication device outputs a timepiece that outputs time, the time on the second communication device side obtained from the second communication device, and the timepiece outputs the timepiece. A difference calculation unit that calculates a difference from the time and stores the difference in the storage unit, wherein the first communication device side key generation unit adds the time output from the clock and the difference stored in the storage unit The second communication device is a communication system that uses, as the common time, a time output from a clock included in the device.

Another aspect of the present invention is a communication method performed by a communication system including a first communication device and a second communication device, wherein the first communication device is based on a plurality of different calculation procedures. Generating key data by a process including selecting one or more calculation procedures based on a time obtained by rounding a fraction less than a common time between the own apparatus and the second communication apparatus; Data is encrypted using key data generated in the communication device, the encrypted data is transmitted to the second communication device, and the second communication device transmits the encrypted data to the second communication device. Receiving from one communication device, generating key data by a process including selecting one or more calculation procedures based on a time obtained by rounding a fraction less than the common time from the plurality of calculation procedures, In the second communication device The encrypted data is decrypted using the key data generated in step S5, and it is determined whether the decrypted data matches predetermined data. In the determination, the decrypted data is If the data does not match, generated by a process including selecting one or more calculation procedures from the plurality of calculation procedures based on a time obtained by shifting a fractional processing time less than the common time by a predetermined amount Generated using the key data generated by the process including selecting one or more calculation procedures based on the time shifted by the predetermined amount in the second communication device. In this communication method, it is determined again whether the data matches the predetermined data.

According to another aspect of the present invention, there is provided key generation for generating key data by a process including selecting one or more calculation procedures from a plurality of different calculation procedures based on a time obtained by rounding less than a minute. A decryption unit that decrypts encrypted data that is data received from another device using the generated key data, and whether or not the decrypted data matches predetermined data An authentication unit that performs authentication by determining, and in the determination by the authentication unit, if the decrypted data does not match predetermined data, the key generation unit Generating key data generated by a process including selecting one or more calculation procedures based on a time obtained by shifting a fractional processing time less than a minute of the time by a predetermined amount, and the authentication unit Using the key data generated by the process including selecting one or more calculation procedures based on the determined time, it is determined again whether the data decrypted by the decryption unit matches the predetermined data , A communication device.

According to another aspect of the present invention, key data is transmitted to a communication device by a process including selecting one or more calculation procedures based on a time obtained by rounding a fraction less than a time from a plurality of different calculation procedures. Generating the received key data, decrypting the encrypted data that is received from another device, and determining whether the decrypted data matches the predetermined data. In the determination, if the decrypted data does not match the predetermined data, one or more based on a time obtained by shifting the fractional processing time by less than a predetermined amount from the plurality of calculation procedures. Generated key data generated by a process including selecting a calculation procedure, and generated by a process including selecting one or more calculation procedures based on the time shifted by the predetermined amount Data using the decoded data to re-determine whether to match the predetermined data, a communication program.

  According to one embodiment of the present invention, security can be improved while suppressing communication costs.

1 is a system configuration example of a communication system according to a first embodiment of the present invention. 2 is a functional configuration example of a terminal device 1; 3 is a functional configuration example of an authentication server 3. 3 is a functional configuration example of a service server 5. It is an example (the 1) of the flowchart which shows the flow of the process performed by the terminal device 1 and the authentication server 3. It is an example (the 2) which shows the flow of the process performed by the terminal device 1 and the authentication server 3. It is a part of flowchart which shows the flow of a process in case multiple time candidates are set. It is a figure which shows the process performed by the 2nd terminal side key generation part 16 and the 2nd server side key generation part 33 in the format of a code. It is a figure which shows the process performed by the 2nd terminal side key generation part 16 and the 2nd server side key generation part 33 in the format of a code. It is a figure showing a series of instructions which an application performs under a simulation environment in an assembly format. It is a figure which shows the process performed by the 2nd terminal side key generation part 16 and the 2nd server side key generation part 33 in the format of a code.

  Hereinafter, a communication system, a communication method, a communication apparatus, and a communication program according to embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a system configuration example of a communication system according to the first embodiment of the present invention. The communication system includes a terminal device 1, an authentication server 3, and a service server 5. These components are connected by a network 9.

[Configuration of Terminal Device 1]
The terminal device 1 is a mobile phone, a tablet PC, a notebook PC, a desktop PC, or other terminal devices. The authentication server 3 is realized by, for example, one or more server devices. When the terminal device 1 receives a service from the service server 5, the authentication server 3 authenticates the terminal device 1, and permits the service if the authentication result is valid. To do. The service server 5 is realized by, for example, one or more server devices, and provides the terminal device 1 with various services such as mail transmission / reception. The network 9 includes, for example, a mobile phone network such as a 3G (3rd. Generation) network, a communication network such as a Wi-Fi network, and an optical communication network. Although FIG. 1 shows the terminal device 1 as a single device, a plurality of terminal devices 1 may be connected to the authentication server 3 and the service server 5 via the network 9.

  FIG. 2 is a functional configuration example of the terminal device 1. The terminal device 1 includes, for example, an input unit 11, an output unit 12, a communication unit 13, an application execution unit 14, a first terminal side key generation unit 15, a second terminal side key generation unit 16, a clock 17, and an encryption processing unit. 18, an authentication token acquisition unit 19, a difference calculation unit 20, and a storage unit 21.

  The storage unit 21 stores an application ID 21A, an application authentication password 21B, an application authentication password expiration date 21C, time difference information 21D, and the like. The application ID 21A is an identifier that identifies the application. The application authentication password 21B is a password for receiving a service by the application. The application authentication password expiration date 21 </ b> C is the expiration date of the application authentication password set by the authentication server 3. The time difference information 21D will be described later.

  The input unit 11 is, for example, a button, a key, a touch panel, a keyboard, a mouse, or the like, and receives input from the user. The output unit 12 includes, for example, a display device such as an LCD (Liquid Crystal Display), a speaker, and the like. The communication unit 13 transmits and receives data to and from other devices via the network 9. The application execution unit 14 executes an application that uses a service provided from the service server 5.

  The first terminal-side key generation unit 15 generates key data K1 to K3 that the encryption processing unit 18 uses for encryption and decryption. The second terminal-side key generation unit 16 generates key data K4 that the encryption processing unit 18 uses for encryption and decryption. The second terminal-side key generation unit 16 performs a process including selecting one or more calculation procedures based on a common time between the terminal device 1 and the authentication server 3 from a plurality of different calculation procedures. Key data K4 that is common between the terminal device 1 and the authentication server 3 is generated. In the first embodiment, the “time common between the terminal device 1 and the authentication server 3” refers to the clock 34 (the time of the authentication server 3 obtained by adding the time difference information 21D to the time output by the clock 17 ( Estimated time) (described later).

  The encryption processing unit 18 encrypts and decrypts data using the key data generated by the first terminal-side key generation unit 15 and the second terminal-side key generation unit 16. As an encryption algorithm using key data, for example, AES (Advanced Encryption Standard) can be used.

  The authentication token acquisition unit 19 transmits an authentication token payout request to the authentication server 3 at a predetermined timing. Then, the authentication token acquisition unit 19 stores at least a part of the authentication token received from the authentication server 3 and decrypted by the encryption processing unit 18 in the storage unit 21.

  The authentication token includes, for example, time information output from the clock 34 of the authentication server 3 when the authentication token is transmitted, an application authentication password 21B, an application authentication password expiration date 21C, and the like. The expiration date 21C of the application authentication password is determined to be, for example, 3 months. When this expiration date expires, the authentication token acquisition unit 19 controls the communication unit 13 to transmit an authentication token payout request to the authentication server 3.

  The difference calculation unit 20 subtracts the time output by the clock 17 when the authentication token is received from the server time information received from the authentication server 3, generates time difference information 21 </ b> D, and stores it in the storage unit 21. The server time information is time information output by the clock 34 when the authentication server 3 generates an authentication token. The time difference information 21 </ b> D is a time reflecting an error between the clock 17 and the clock 34.

[Configuration of Authentication Server 3]
FIG. 3 is a functional configuration example of the authentication server 3. The authentication server 3 includes, for example, a communication unit 31, a first server side key generation unit 32, a second server side key generation unit 33, a clock 34, an encryption processing unit 35, an authentication token generation unit 36, an authentication unit 37, a storage The unit 38 and the like are provided.

  The arrows shown in FIGS. 2 and 3 exemplify typical information flows in the communication system, and information flows other than those shown in FIGS.

  The storage unit 38 stores an application ID 38A, an application authentication password 38B, an application authentication password expiration date 38C, server time information 38D, terminal identification information 38E, SIM (Subscriber Identity Module) identification information 38F, and the like.

  As the terminal identification information 38E, for example, IMEI (International Mobile Equipment Identity) can be used. As the SIM identification information 38F, for example, a multiple subscriber number (MSN), an integrated circuit card ID (ICCID), a Wi-Fi (registered trademark) password, or the like can be used. It is assumed that the SIM identification information 38F is shared between the terminal device 1 and the authentication server 3 in advance by network authentication, for example.

  The communication unit 31 transmits and receives data to and from other devices via the network 9.

  The first server side key generation unit 32 generates key data K1 and K2 used by the encryption processing unit 35 for encryption and decryption. The second server side key generation unit 33 generates key data K4 used by the encryption processing unit 35 for encryption and decryption. The second server side key generation unit 33 performs a process including selecting one or more calculation procedures based on the time output from the clock 34 from a plurality of different calculation procedures, and the terminal device 1 and the authentication server 3. Key data K4 that is common between the two is generated.

  The encryption processing unit 35 encrypts and decrypts data using the key data generated by the first server side key generation unit 32 and the second server side key generation unit 33. As an encryption algorithm using the key data, for example, AES can be used.

  In response to the authentication token payout request received from the terminal device 1, the authentication token generation unit 36 generates an authentication token and transmits the authentication token to the terminal device 1. The authentication unit 37 authenticates authentication information received from the terminal device 1 by the service server 5 and transmits an authentication result to the service server 5.

  The storage unit 38 stores an application ID 38A, an application authentication password 38B, an application authentication password expiration date 38C, server time information 38D, terminal identification information 38E, SIM identification information 38F, and the like.

[Configuration of Service Server 5]
FIG. 4 is a functional configuration example of the service server 5. The service server 5 includes, for example, a communication unit 51, an authentication request unit 52, a service providing unit 53, and the like.

  The communication unit 51 transmits / receives data to / from other devices via the network 9. The authentication request unit 52 transmits the authentication information received from the terminal device 1 to the authentication server 3 and requests authentication. If the authentication request unit 52 receives an authentication failure from the authentication server 3 in response to the authentication request, the authentication request unit 52 notifies the terminal device 1 to that effect. The service providing unit 53 provides a service to the terminal device 1 when receiving a successful authentication from the authentication server 3 in response to the request for authentication.

  When a plurality of service servers 5 are provided, each service server 5 may provide a different service. For example, the service server 5 can be a mail server, a POP (Post Office Protocol) server, an information providing server, or the like.

[Flowchart (Part 1)]
When the application is instructed by the user tapping the icon of the terminal device 1 or the like, the terminal device 1 and the authentication server 3 use a one-time password by exchanging random numbers as illustrated below. Send and receive information.

  FIG. 5 is an example (part 1) of a flowchart showing a flow of processing executed by the terminal device 1 and the authentication server 3. Each procedure in the flowchart of FIG. 5 is started, for example, when an instruction to start an application is given by the user.

  First, the application execution unit 14 of the terminal device 1 starts an application (step S100), and the authentication token acquisition unit 19 generates a random number R1 (step S102). The random number R1 and the random number R2 to be described later are generated by a pseudo-random number generation algorithm such as Menselne Twister or PRNG (Pseudo Random Number Generator).

  Next, the first terminal-side key generation unit 15 of the terminal device 1 generates key data K1 based on SIM identification information read from a module (not shown) or the like (step S104). Then, the encryption processing unit 18 encrypts the random number R1 using the key data K1 (step S106). The encrypted random number R1 is transmitted to the authentication server 3 (step S108).

  When receiving the encrypted random number R1, the first server-side key generation unit 32 of the authentication server 3 generates key data K1 based on the SIM identification information 38F of the terminal 1 stored in the storage unit 38 (step S1). S110). Then, the encryption processing unit 35 decrypts the encrypted random number R1 using the key data K1 (step S112).

  Next, the authentication token generation unit 36 of the authentication server 3 generates a random number R2 (step S114), and the encryption processing unit 35 encrypts the random number R2 using the key data K1 (step S116). The encrypted random number R2 is transmitted to the terminal device 1 (step S118).

  The encryption processing unit 18 of the terminal device 1 decrypts the encrypted random number R2 using the key data K1 (step S120). Next, the authentication token acquisition unit 19 generates an authentication token payout request (step S122). Next, the first terminal-side key generation unit 15 generates key data K2 based on the random number R1 and the random number R2 (step S124). Then, the encryption processing unit 18 encrypts the terminal identification information of the own device (terminal device 1) and the authentication token payout request read from a module (not shown) using the key data K2 (step S126). The communication unit 13 transmits the encrypted terminal identification information and the authentication token payout request to the authentication server 3 (step S128).

  The first server-side key generation unit 32 of the authentication server 3 generates key data K2 based on the random number R1 and the random number R2 (step S130). Next, the encryption processing unit 35 decrypts the terminal identification information and the authentication token payout request using the key data K2 (step S132). Next, the authentication token generation unit 36 generates an application ID and an authentication token (step S134). The authentication token includes, for example, an application authentication password, an expiration date of the application authentication password, and server time information. The server time information is time information acquired from the clock 34 when generating the authentication token in step S134.

  The authentication token generator 36 uses the information set as described above as application ID 38A, application authentication password 38B, application authentication password expiration date 38C, server time information 38D, terminal identification information 38E, and SIM identification information 38F. The data is stored in the storage unit 38 (step S136). Then, the encryption processing unit 35 encrypts the application ID and the authentication token using the key data K2 (step S138). The communication unit 31 transmits the encrypted application ID and authentication token to the terminal device 1 (step S140).

  The encryption processing unit 18 of the terminal device 1 decrypts the application ID and the authentication token using the key data K2 (step S142). Next, the difference calculation unit 20 subtracts the time output by the clock 17 from the server time information to generate time difference information (step S144).

  Next, the first terminal-side key generation unit 15 of the terminal device 1 generates key data K3 based on the SIM identification information and the terminal identification information (step S146). Using the key data K3, the encryption processing unit 18 encrypts the application ID, the application authentication password, the expiration date information of the application authentication password, and the time difference information (step S148). The encrypted application ID, the application authentication password, the expiration date information of the application authentication password, and the time difference information are the application ID 21A, the application authentication password 21B, the expiration date 21C of the application authentication password, and the time difference information 21D. Stored in the storage unit 21.

[Flowchart (Part 2)]
When the application ID 21A or the like is stored in the storage unit 21 by the procedure of the flowchart illustrated in FIG. 5, the user can receive a service from the application. In this state, for example, when the user makes a service use request by pressing a mail acquisition button or the like, the terminal device 1 and the authentication server 3 perform a key data generation procedure in which a calculation procedure is selected based on time. Key data K4 is generated and encrypted communication is performed.

  FIG. 6 is an example (part 2) of a flowchart showing a flow of processing executed by the terminal device 1 and the authentication server 3. Each procedure in the flowchart of FIG. 6 is started, for example, when a service use request is made by the user.

  First, the first terminal-side key generation unit 15 of the terminal device 1 generates the key data 3 based on the terminal identification information and the SIM identification information of the own device (terminal device 1) (step S200). Next, the encryption processing unit 18 decrypts the application ID 21A, the application authentication password 21B, the application authentication password expiration date 21C, and the time difference information 21D stored in the storage unit 21, using the key data K3 (step S21). S202).

  Next, the application execution unit 14 of the terminal device 1 determines whether or not the expiration date of the application authentication password has expired (step S204). When the expiration date of the application authentication password has expired, for example, the procedure of the flowchart of FIG. 5 is executed (step S206).

  Next, the second terminal-side key generation unit 16 of the terminal device 1 adds the time output by the clock 17 and the time indicated by the difference time information, and the estimated time of the authentication server 3 (the time common to the authentication server 3). Is calculated (step S208). Next, the second terminal-side key generation unit 16 rounds off the minutes less than the added estimated time of the authentication server 3 to a time in minutes (step S210). The rounding process in step S210 may be any process such as (a) rounding down, (b) rounding up, (c) rounding down if less than 30 seconds / rounding up if longer than 30 seconds.

  And the 2nd terminal side key generation part 16 of the terminal device 1 produces | generates key data K4 using the rounded time (step S212). Details of the processing in step S212 will be described later.

  The encryption processing unit 18 of the terminal device 1 encrypts the application authentication password, the terminal identification information, and the SIM identification information using the key data K4 (step S214). The application ID, the application authentication password, the terminal identification information, and the SIM identification information encrypted in step S214 are transmitted to the service server 5 (step S216).

  The authentication request unit 52 of the service server 5 transfers the received application ID, the encrypted application authentication password, the terminal identification information, and the SIM identification information to the authentication server 3 (step S218).

  When the information is transferred from the service server 5, the second server side key generation unit 33 of the authentication server 3 rounds down the second of the time output by the clock 34 to the time in minutes (step S 220). ). As the fraction processing, any processing may be performed, but it is desirable that processing common to the terminal device 1 is performed.

  Next, the second server-side key generation unit 33 of the authentication server 3 generates key data K4 using the rounded time (step S224). The process in step S224 is the same as the process performed by the terminal device 1 as step S212. Therefore, if the “rounded time” in step 224 matches the “rounded time” in S212, the key data K4 generated by both the terminal device 1 and the authentication server 3 match.

  Then, the encryption processing unit 35 of the authentication server 3 decrypts the application authentication password, the terminal identification information, and the SIM identification information using the generated key data K4 (step S226).

  Next, the authentication unit 37 of the authentication server 3 searches the storage unit 38 using the application ID as a key, and acquires the application authentication password 38B, the expiration date 38C of the application authentication password, the terminal identification information 38E, and the SIM identification information 38F. (Step S228). Next, the authentication unit 37 verifies whether or not the expiration date of the application authentication password has expired (step S230). Further, whether the information decrypted in step S226 matches the information acquired from the storage unit 38. Authentication is performed by determining whether or not (step S232). The authentication unit 37 notifies the authentication result to the service server 5 (step S234). The authentication unit 37 performs an authentication token payout process or the like when the expiration date of the application authentication password has expired.

  The service providing unit 53 of the service server 5 determines whether or not the authentication by the authentication server 3 has succeeded (step S236). If the authentication is successful, the service providing unit 53 provides the terminal device 1 with a service (for example, transmission of mail contents) (step S238). In the terminal device 1, the application execution unit 14 causes the output unit 12 to output the service content (step S240).

  Here, the “rounded time” calculated in the terminal device 1 and the “rounded time” calculated in the authentication server 3 are processed in the terminal device 1 and the authentication server 3 before and after switching of minutes. If the communication time becomes longer, there is a possibility of deviation. On the other hand, the authentication server 3 determines that the terminal device 1 is based on a slightly different time such as 1 minute before, 1 minute, 2 minutes before, 2 minutes after the “rounded time” calculated by itself. Considering the possibility of generating K4, a plurality of time candidates may be set as described below.

  FIG. 7 is a part of a flowchart showing a flow of processing when a plurality of time candidates are set. FIG. 7 shows a modification of the processing from step S220 to step S234 in the flowchart of FIG. 6, and omits parts other than the changed part. Moreover, the same step number is attached | subjected about the process which is common between FIG.

  In FIG. 7, when the fraction processing in step S220 is performed, the second server-side key generation unit 33 of the authentication server 3 sets a plurality of time candidates, and first selects the first candidate time candidate (step S222). ). For example, if the rounding process in step S220 is “rounded down” and the time output by the clock 34 is 12:01:25, the second server-side key generation unit 33 uses the rounded time ( 12:01) is the first candidate, the time when 1 minute is added to this (12:02) is the second candidate, and the time when 12 minutes is added (12:03) is the third candidate. As described above, a predetermined number of time candidates are set in order. Not limited to this, the second server-side key generation unit 33 may set a time candidate obtained by subtracting a predetermined number from the time rounded by the fraction processing. Then, the second server-side key generation unit 33 generates key data K4 using the selected time candidate (step S224).

  Thereafter, similarly to FIG. 6, the encryption processing unit 35 decrypts the application authentication password using the key data K4 (step S226), and the authentication unit 37 acquires the application authentication password 38B (step S228). It is verified whether the password for application authentication has expired (step S230), and authentication is performed by determining whether the information decrypted in step S226 matches the information acquired from the storage unit 38 (step S230). Step S232).

  In FIG. 7, when authentication is performed in step S232, the second server-side key generation unit 33 of the authentication server 3 determines whether the authentication is successful (step S250). If the authentication fails, the second server side key generation unit 33 has already selected a predetermined number (for example, three) of time candidates, and determines whether or not a predetermined number of key data K4 has been generated based on this. Determination is made (step S252). If the predetermined number of time candidates have not yet been selected, the second server-side key generation unit 33 selects the next time candidate (step S254) and returns to step S224. As a result, key data K4 is generated based on the newly selected time candidate, and the application authentication password and the like are decrypted. If the predetermined number of time candidates have already been selected, the authentication server 3 proceeds to step S234 and notifies the service server 5 of the authentication failure.

[Key data generation procedure in which calculation procedure is selected based on time]
Hereinafter, the processing of step S212 and step S224 in the flowchart of FIG. 6 or 7 will be described in more detail. Note that the calculation procedure shown below as a specific example is merely an example, and any calculation procedure may be executed as long as the calculation procedure is selected based on time.

The second terminal side key generation unit 16 and the second server side key generation unit 33 use functions defined as follows, for example. “Hash ()” is a function for obtaining a hash value of a value in parentheses. The time information is the “rounded time” generated in step S210 in the second terminal-side key generation unit 16. The time information is the “rounded time” generated in step S220 in the second server-side key generation unit 33, or the time candidate selected in step S222 or step S254 (when executing the flowchart of FIG. 7). ).
x = hash (time information)
y = hash (password for app authentication)
N = Value of the least significant byte of the password for application authentication α = Value of the most significant byte of the password for application authentication

  FIG. 8 and FIG. 9 are diagrams illustrating processing executed by the second terminal-side key generation unit 16 and the second server-side key generation unit 33 in the form of codes. FIG. 8 is a diagram showing main loop processing executed by the second terminal-side key generation unit 16 and the second server-side key generation unit 33, and FIG. 9 shows functions called by the main loop processing. FIG.

  As shown in FIG. 8, the second terminal-side key generation unit 16 and the second server-side key generation unit 33 repeatedly execute N times by selecting and executing any one of the functions func1 to func3 ( (In the figure, (1), (2) and (5) correspond). Which function is selected is determined by the remainder obtained by dividing the parameter α by 3 (corresponding to (3) to (4) in the figure).

  9A shows the contents of the function func1 called by the main loop process, FIG. 9B shows the contents of the function func2, and FIG. 9C shows the contents of the function func3. In FIG. 9, “OR” indicates that a bit string in which the logical sum of each bit of the left and right operands (bit string) of the operator is arranged is obtained, and “AND” indicates that the left and right operands (bit string) of the operator are “XOR” indicates that a bit string in which exclusive OR of each bit of the left and right operands (bit strings) of the operator is arranged is obtained. In FIG. 9, ms is a function for obtaining the most significant bit, and ls is a function for obtaining the least significant bit.

  The parameter α is irrelevant to the value of the most significant byte of the application authentication password, that is, the time information, in the first loop process shown in FIG. 8, but as shown in FIG. 9, in the second and subsequent loop processes. , Based on the contents of “x” reflecting the time information. Therefore, in the second and subsequent loop processing, one of a plurality of different functions (calculation procedures) func1 to func3 is selected based on the time information.

  Then, as a result of N times of loop processing, for example, the bit string “y” finally obtained as the operation result is set in the key data K4.

  In the above example, N for determining the number of loops is set to the value of the least significant byte of the password for application authentication. However, N for determining the number of loops is also set to a value based on time information. It's okay.

  As described above, the communication system 1 according to the present embodiment can improve the security by generating the key data K4 by the process including the selection of the calculation procedure based on the time information.

  As described above, when the application installed in the terminal device 1 describes the encryption processing procedure and the key data generation procedure, the analyst can transfer the application including the installed key data generation procedure to another computer device. It is possible to analyze the key data generation procedure. FIG. 10 is a diagram showing a series of instructions executed by the application in a simulation environment (in the above-mentioned “other computer apparatus”) in an assembly format. The analyst may be able to see the flow of instructions as shown in FIG. Therefore, if the key data generation procedure is always the same, it is easy to determine where the key data generation procedure is, and by taking into account the value stored in the memory as the application is executed, There is a high possibility that the key data generation procedure will be revealed.

  On the other hand, the second terminal-side key generation unit 16 and the second server-side key generation unit 33 of the present embodiment obtain the key data K4 by a process including selection of a calculation procedure based on time information. In order to generate the key data, the key data generation procedure is different every time (except when the key data is generated at the same time and at the same time). Accordingly, the instructions (1) to (10) shown in FIG. 10 are executed in the order of (8) → (4) → (2) → (1) → (7), or (5) → (1 ) → (9) → (3), it is difficult for the analyst to determine where the key data is generated from where. As a result, the communication system 1 of the present embodiment can improve security.

  Further, once the server time information is acquired and the time difference information is stored in the storage unit 21, the terminal device 1 and the authentication server 3 are common to the terminal device 1 and the authentication server 3 based on the respective clocks. Time information can be acquired. For this reason, since it is not necessary to perform a process of transmitting / receiving common time information each time encrypted communication is performed, the communication cost does not increase due to changing the key data generation procedure each time. The acquisition of the server time information itself is executed as a normal process for receiving service provision, and thus does not cause an increase in communication cost.

  Also, sending and receiving time information every time encrypted communication can give the analyst a hint that the time information may be used in the key data generation procedure if the analyst intercepts the sent and received information There is sex. However, since the communication system 1 of the present embodiment does not transmit / receive time information every time encrypted communication is performed, it is possible to prevent a decrease in security.

  As a result, the communication system of this embodiment can improve security while suppressing communication costs.

  Note that the key data generation procedure in which the calculation procedure is selected based on the time may be performed in a scene other than the scene where authentication is performed. For example, it may be performed when the terminal device 1 transmits / receives data to / from the service server 5 or may be performed in other situations.

[Application example of key data generation procedure]
In the above, a simple key data generation procedure using the time information and the application authentication password as input parameters has been exemplified. However, by increasing the input parameters, it is possible to perform encryption with higher security.

  For example, the second terminal side key generation unit 16 and the second server side key generation unit 33 can use terminal identification information, SIM identification information, and the like as input parameters in addition to time information and an application authentication password. . Assume that there are k input parameters y1, y2,..., Yk, for example, and at least one input parameter reflects time information. Then, for example, m different functions func1 to funcm are defined, and the loop processing illustrated in FIG. 11 is executed. FIG. 11 is a diagram illustrating processing executed by the second terminal-side key generation unit 16 and the second server-side key generation unit 33 in the form of a code. The function funcm is conceptually expressed as follows, for example. In each definition formula, f1m, f2m, fkm, and gm are different functions when the argument m is different, and are arbitrary functions (calculation procedures) using data in parentheses as input parameters.

funcm {
y1 = f1m (y1, y2,..., yk, α);
y2 = f2m (y1, y2,..., yk, α);
...
yk = fkm (y1, y2,..., yk, α);
α = gm (y1, y2,..., yk, α);
}

[Summary]
According to the communication system including the terminal device 1 and the authentication server 3 of the present embodiment described above, it is possible to improve security while suppressing communication costs.

  Second Embodiment

  The communication system according to the second embodiment of the present invention will be described below. The clocks 17 and 34 included in the terminal device 1 and the authentication server 3 in the second embodiment are clocks that can acquire a standard time, such as a radio clock. For this reason, in the terminal device 1 which concerns on 2nd Embodiment, it is possible to abbreviate | omit the difference calculating part 20, and it is not necessary to store the time difference information 21D in the memory | storage part 21. FIG.

  In this case, the time output from the clock 17 when the encrypted data is generated by the terminal device 1 and the time output from the clock 34 when the authentication server 3 receives and decrypts the encrypted data match. Probability is high. Further, if fractional processing of less than a minute is performed in both the terminal device 1 and the authentication server 3, the communication time is likely to be within the error range if the communication environment is good. For this reason, the second terminal-side key generation unit 16 and the second server-side key generation unit 33 use the times (or rounded values obtained by rounding off) output from the clocks 17 and 34 as common times, respectively. deal with.

<Hardware configuration>
The terminal device 1, the authentication server 3, and the service server 5 in each embodiment described above have a computer system therein. The “computer system” includes a memory device such as a CPU (Central Processing Unit) and a RAM (Random Access Memory), a storage device such as a ROM (Read Only Memory), an HDD (Hard Disk Drive), and an SSD (Solid State Drive). It includes hardware such as a drive device and a peripheral device in which a medium can be mounted.

  And the application execution part 14, the 1st terminal side key generation part 15, the 2nd terminal side key generation part 16, the encryption process part 18, the authentication token acquisition part 19, the difference calculating part 20, authentication of the terminal device 1 mentioned above The operation process of the first server side key generation unit 32, the second server side key generation unit 33, the encryption processing unit 35, the authentication token generation unit 36, the authentication unit 37, etc. of the server 3 is, for example, in the form of a program. The program is stored in a computer-readable recording medium, and the above processing is performed by the computer system reading and executing this program. Note that the processing of each functional unit need not be performed by executing a program, and some functional units are realized by hardware such as IC (Integrated Circuit) and LSI (Large Scale Integration). Also good.

  The “computer-readable recording medium” refers to a portable medium such as a flexible disk, an optical disk, a magneto-optical disk, a ROM, and a CD-ROM, and a storage device such as an HDD built in the computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included.

  The program may be for realizing a part of the functions described above, and further, the program described above may be realized in combination with a program already recorded in a computer system. good.

  The second terminal side key generation unit 16 in each of the above embodiments is an example of a “first communication device side key generation unit”, and the second server side key generation unit 33 includes “second communication”. It is an example of a “device-side key generation unit”.

<Others>
As mentioned above, although the form for implementing this invention was demonstrated using embodiment, this invention is not limited to such embodiment at all, In the range which does not deviate from the summary of this invention, various deformation | transformation and substitution Other components can be added.

  For example, in the first embodiment, the key data K4 is generated based on the time obtained as a result of the calculation based on the time difference information in the terminal device 1, and the key is based on the time output from the clock 34 of the own device by the authentication server. Although the data K4 is generated, this relationship may be reversed. That is, the authentication server 3 holds the time difference information in advance, the terminal device 1 generates the key data K4 based on the time output from the clock 17, and the authentication server 3 receives the clock when receiving the encrypted data. The key data K4 may be generated based on the time obtained by adding (or subtracting) the time difference information to the time outputted by 34.

DESCRIPTION OF SYMBOLS 1 Terminal device 11 Input part 12 Output part 13 Communication part 14 Application execution part 15 1st terminal side key generation part 16 2nd terminal side key generation part 17 Clock 18 Cryptographic process part 19 Authentication token acquisition part 20 Difference calculation part 21 Storage unit 21A App ID
21B Application authentication password 21C Application authentication password expiration date 21D Time difference information 3 Authentication server 31 Communication unit 32 First server side key generation unit 33 Second server side key generation unit 34 Clock 35 Cryptographic processing unit 36 Authentication token Generation unit 37 Authentication unit 38 Storage unit 38A Application ID
38B Application Authentication Password 38C Application Authentication Password Expiration Date 38D Server Time Information 38E Terminal Identification Information 38F SIM Identification Information 5 Service Server 9 Network

Claims (6)

A communication system comprising a first communication device and a second communication device,
The first communication device is:
Key data by a process including selecting one or more calculation procedures from a plurality of different calculation procedures based on a time obtained by rounding a fraction less than a common time between the own device and the second communication device. A first communication device side key generation unit for generating
An encryption unit that encrypts data using the key data generated by the first communication device side key generation unit;
A transmission unit for transmitting the encrypted data to the second communication device,
The second communication device is:
A receiving unit for receiving the encrypted data from the first communication device;
A second communication device-side key generation unit that generates key data by a process including selecting one or more calculation procedures from the plurality of calculation procedures based on a time obtained by performing fraction processing on less than the common time; ,
A decryption unit for decrypting the encrypted data using the key data generated by the second communication device side key generation unit;
An authentication unit that performs authentication by determining whether or not the decrypted data matches predetermined data;
With
In the determination by the authentication unit, if the decrypted data does not match the predetermined data,
The second communication device side key generation unit selects one or more calculation procedures from the plurality of calculation procedures based on a time obtained by shifting a fractional processing time less than the common time by a predetermined amount. Generate key data generated by the process including,
The authentication unit uses the key data generated by the process including selecting one or more calculation procedures based on the time shifted by the predetermined amount, and the data decrypted by the decryption unit matches the predetermined data Determine again whether or not to
Communications system. The communication system according to claim 1,
The plurality of different arithmetic procedures are arithmetic procedures with different combinations of logical operations, arithmetic procedures with different numbers of repeated operations, or repeated operations with different combinations of logical operations and repeated operations. The number of times is a different calculation procedure.
Communications system. The communication system according to claim 1 or 2,
The first communication device is:
A clock that outputs the time,
A difference calculation unit that calculates a difference between the time on the second communication device acquired from the second communication device and the time output by the timepiece and stores the difference in a storage unit;
The first communication device side key generation unit uses, as the common time, a time obtained by adding the time output from the clock and the difference stored in the storage unit,
The second communication device uses a time output by a clock included in the device as the common time.
Communications system. A communication method performed by a communication system including a first communication device and a second communication device,
The first communication device is
Key data by a process including selecting one or more calculation procedures from a plurality of different calculation procedures based on a time obtained by rounding a fraction less than a common time between the own device and the second communication device. Produces
Encrypting the data using the key data generated in the first communication device;
Sending the encrypted data to the second communication device;
The second communication device is
Receiving the encrypted data from the first communication device;
From the plurality of calculation procedures, generate key data by a process including selecting one or more calculation procedures based on a time obtained by rounding the fraction of the common time.
Decrypting the encrypted data using the key data generated in the second communication device ;
It is determined whether or not the decoded data matches the predetermined data, and in the determination, if the decoded data does not match the predetermined data,
From the plurality of calculation procedures, generate key data generated by a process including selecting one or more calculation procedures based on a time shifted by a predetermined amount from a time when the fractional processing of less than the common time is performed,
Using the key data generated by the process including selecting one or more calculation procedures based on the time shifted by the predetermined amount in the second communication device, the decrypted data matches the predetermined data. Determine again whether or not
Communication method. A key generation unit that generates key data by a process including selecting one or more calculation procedures based on a time obtained by rounding a fraction less than a time from a plurality of different calculation procedures;
A decryption unit for decrypting encrypted data that is data received from another device using the generated key data;
An authentication unit that performs authentication by determining whether or not the decrypted data matches predetermined data,
In the determination by the authentication unit, when the decrypted data does not match the predetermined data,
The key generation unit generates key data generated by a process including selecting one or more calculation procedures from the plurality of calculation procedures based on a time obtained by shifting a time obtained by rounding a fractional part of the time by a predetermined amount. Produces
The authentication unit uses the key data generated by the process including selecting one or more calculation procedures based on the time shifted by the predetermined amount, and the data decrypted by the decryption unit matches the predetermined data Determine again whether or not to
Communication device. In the communication device,
Key data is generated by a process including selecting one or more calculation procedures based on a time obtained by rounding a fraction of a time from a plurality of different calculation procedures,
Using the generated key data, the data received from another device, the encrypted data is decrypted,
In the case where the decrypted data does not match the predetermined data in the determination, it is determined whether or not the decrypted data matches the predetermined data.
From the plurality of calculation procedures, generate key data generated by a process including selecting one or more calculation procedures based on a time shifted by a predetermined amount from the time when the fractional processing of the time is less than a minute,
Using the key data generated by the process including selecting one or more calculation procedures based on the time shifted by the predetermined amount, it is determined again whether or not the decrypted data matches the predetermined data. ,
Communication program.

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