JP2013232729A - Authentication device, authentication method, and authentication program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To authenticate a message transmitted from a user terminal.SOLUTION: An authentication device receives a message from a user terminal including a time stamp indicating the time when the user terminal has transmitted the message, on the basis of the received message and authentication information stored in a user information storage unit in association with a user ID corresponding to the user terminal having transmitted the message, performs authentication processing which determines whether the received message matches a message that has been already transmitted from the user terminal corresponding to the user ID, and if the received message does not match the message that has been already transmitted from the user terminal corresponding to the user ID, stores authentication information corresponding to the message in the user information storage unit.

Description

  The present invention relates to a technique for authenticating a message transmitted from a user terminal.

  As a technique for authenticating a message transmitted from a user terminal by a server device, for example, a method using HMAC (Keyed-Hashing for Message Authentication code) in which a one-way hash function is combined with a MAC (Message Authentication Code) is used. Exists. In this method, a common key (Ks) is shared in advance between the user terminal and the server device. The user terminal calculates an HMAC value (H (m, Ks)) that is a hash value based on the original text (m) and the common key (Ks) of the message transmitted to the server device. The user terminal transmits a message (m || H (m, Ks)) including the original text (m) of the message and the HMAC value (H (m, Ks)) to the server device. The server device calculates the HMAC value (H (m, Ks)) based on the original text (m) of the message received from the user terminal and the common key (Ks) shared in advance, and the calculated HMAC value and the user The message is authenticated by determining whether the HMAC value received from the terminal matches. In this way, since a correct HMAC value cannot be generated even if a third party who does not know the common key falsifies the message, it is possible to detect alteration of the message by the third party. However, when a message containing an HMAC value (m || H (m, Ks)) transmitted from the user terminal to the server device is intercepted by a third party, the message that the third party has intercepted is transmitted to the server device. Authentication succeeds when retransmitted to. Such an attack is called a replay attack. In order to prevent such a replay attack, for example, Patent Document 1 describes performing authentication by a challenge / response method. Patent Document 2 describes a method for performing authentication using a sequence number.

JP 2010-193110 A JP 2010-273225 A

  However, in the challenge / response authentication, it is necessary to share random data called nonce in advance between the user terminal and the server device, so that the number of communications is doubled. In the method of performing authentication using a sequence number, the user terminal and the server device must share the sequence number. Therefore, it is necessary to manage the sequence number on the user terminal side and the sequence number is lost. It is not possible to perform secure communication. Therefore, it is desirable that the user terminal and the server device communicate efficiently while preventing a replay attack.

  The present invention has been made in view of such a situation, and provides an authentication device, an authentication method, and an authentication program for authenticating a message transmitted from a user terminal.

  In order to solve the above-described problem, the present invention provides a user ID for identifying a user and a message transmitted from a user terminal corresponding to the user ID matches a message already transmitted from the user terminal corresponding to the user ID. A user information storage unit that stores user information associated with authentication information for determining whether or not, and a message including a time stamp indicating the time when the user terminal transmitted the message from the user terminal The message received by the receiving unit based on the receiving unit, the message received by the receiving unit, and the authentication information stored in the user information storage unit in association with the user ID corresponding to the user terminal that transmitted the message Authentication processing for determining whether the message matches the message already transmitted from the user terminal corresponding to the user ID When the authentication unit and the authentication unit determine that the message received by the receiving unit does not match the message already transmitted from the user terminal corresponding to the user ID, the authentication information corresponding to the message is stored in the user information storage. An authentication information registration unit stored in the unit.

  In the present invention, the authentication information is a time stamp, and the authentication unit uses the first time indicated by the time stamp included in the message received by the reception unit and the user ID corresponding to the user terminal that transmitted the message. The authentication process is performed by comparing the second time indicated by the time stamp which is the authentication information associated with and stored in the user information storage unit.

  Further, according to the present invention, if the first time is later than the second time, the authentication unit does not match the message received by the receiving unit with the message already transmitted from the user terminal corresponding to the user ID. If the first time is not later than the second time, it is determined that the message received by the receiving unit matches the message already transmitted from the user terminal corresponding to the user ID, To do.

  According to the present invention, the authentication information is a signature value based on a parameter included in the message, the receiving unit receives a message including the signature value from the user terminal, and the authentication unit receives the message received by the receiving unit. Is compared with the second signature value that is authentication information stored in the user information storage unit in association with the user ID corresponding to the user terminal that transmitted the message. The authentication process is performed.

  Further, according to the present invention, if the first signature value matches the second signature value, the authentication unit matches the message already received from the user terminal corresponding to the user ID. If the first signature value does not match the second signature value, the message received by the receiving unit is determined not to match the message already transmitted from the user terminal corresponding to the user ID. It is characterized by.

  Further, according to the present invention, the reception unit receives a message including a plurality of operation requests, and the authentication apparatus has already transmitted the message received by the reception unit from the user terminal corresponding to the user ID by the authentication unit. An execution unit that executes processing corresponding to a plurality of operation requests included in the message when it is determined not to match the message is provided.

  Further, the present invention determines a user ID for identifying a user and whether or not a message transmitted from a user terminal corresponding to the user ID matches a message already transmitted from the user terminal corresponding to the user ID. An authentication method of an authentication apparatus comprising a user information storage unit that stores user information associated with authentication information of a user, wherein a message including a time stamp indicating a time at which the user terminal transmits a message is received from the user terminal. The received message corresponds to the user ID based on the receiving step, the received message, and the authentication information stored in the user information storage unit associated with the user ID corresponding to the user terminal that transmitted the message. Authentication process to determine whether the message matches the message already sent from the user terminal And storing authentication information corresponding to the message in the user information storage unit when it is determined that the received message does not match the message already transmitted from the user terminal corresponding to the user ID. An authentication method characterized by the above.

  Further, the present invention determines a user ID for identifying a user and whether or not a message transmitted from a user terminal corresponding to the user ID matches a message already transmitted from the user terminal corresponding to the user ID. Receiving a message including a time stamp indicating a time at which the user terminal transmitted the message from the user terminal, in a computer of the authentication apparatus including a user information storage unit that stores user information associated with the authentication information of And the user terminal whose received message corresponds to the user ID based on the received message and the authentication information associated with the user ID corresponding to the user terminal that transmitted the message and stored in the user information storage unit The authentication process for determining whether or not the message already matches the message sent from And a step of storing authentication information corresponding to the message in the user information storage unit when it is determined that the received message does not match the message already transmitted from the user terminal corresponding to the user ID. It is.

  As described above, according to the present invention, the authentication apparatus receives from the user terminal a message including a time stamp indicating the time when the user terminal transmitted the message, and the received message and the user who transmitted the message. Whether the received message matches the message already transmitted from the user terminal corresponding to the user ID based on the authentication information stored in the user information storage unit in association with the user ID corresponding to the terminal If the received message does not match the message already transmitted from the user terminal corresponding to the user ID, the authentication information corresponding to the message is stored in the user information storage unit. Therefore, the message transmitted from the user terminal can be authenticated.

It is a block diagram which shows the structural example of the cloud system 1 by the 1st Embodiment of this invention. It is a figure which shows the example of data of the user information by the 1st Embodiment of this invention. It is a figure which shows the example of the message by the 1st Embodiment of this invention. It is a figure which shows the example of the operation request | requirement by the 1st Embodiment of this invention. It is a figure which shows the operation example of the cloud system by the 1st Embodiment of this invention. It is a figure which shows the example of the processing result according to the message by the 1st Embodiment of this invention. It is a figure which shows the example of the processing result according to the message by the 1st Embodiment of this invention. It is a figure which shows the example of data of the user information by the 3rd Embodiment of this invention. It is a figure which shows the operation example of the cloud system by the 3rd Embodiment of this invention. It is a figure which shows the example of the processing result according to the message by the 3rd Embodiment of this invention. It is a figure which shows the example of the processing result according to the message by the 3rd Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a block diagram illustrating a configuration of a cloud system 1 according to the present embodiment. The cloud system 1 includes computer devices including a plurality of physical machines 10 (physical machine 10-1, physical machine 10-2, physical machine 10-3,...), A cloud server 20, and a user terminal 30. These computer apparatuses are connected via a network. A plurality of physical machines 10 (physical machine 10-1, physical machine 10-2, physical machine 10-3,...) Have the same configuration, and are “−1” and “−2” unless otherwise distinguished. In the following description, the physical machine 10 is omitted. Here, three physical machines 10 are shown, but any number of physical machines 10 may be connected.

  The physical machine 10 is a computer device including computer resources such as a CPU (Central Processing Unit), a memory, and a disk (HDD: Hard disk drive), and is connected to the user terminal 30 and the cloud server 20 via a network. On the computer resource of the physical machine 10, a virtual machine corresponding to a request from the user terminal 30 is activated and operates.

  In response to a request from the user terminal 30, the cloud server 20 activates and operates a virtual machine on any of the plurality of physical machines 10. The cloud server 20 includes a user information storage unit 21, a communication unit 22, an authentication unit 23, a cloud controller unit 27, and a control unit 28.

  The user information storage unit 21 determines whether a user ID (Identifier) for identifying a user and a message transmitted from the user terminal 30 corresponding to the user ID match a message already transmitted from the user terminal 30. User information associated with authentication information for determination is stored. FIG. 2 is a diagram illustrating a data example of user information stored in the user information storage unit 21. The user information includes information in which the common key (Ks) and the last request time (Tl) are associated with each other for each user ID. The user ID is identification information for identifying the user. The common key (Ks) is a secret key shared in advance between the user identified by the user ID and the cloud server 20. The last request time is a time stamp included in a message transmitted from the user terminal 30 corresponding to the user ID. The time stamp is expressed in a format of “YYYY-MM-DDTHH: MM: SSZ”. In this embodiment, this time stamp is used as authentication information.

  The communication unit 22 receives from the user terminal 30 a message including a time stamp indicating the time when the user terminal 30 transmits the message. FIG. 3 is a diagram illustrating an example of a message that the communication unit 22 receives from the user terminal 30. Here, the example of the message by the GET parameter in the HTTP request is shown. That is, parameters of Operation, MachineTemplate, Count, UserID, Time, and HMAC are added as parameters for URL (https://a.com).

  Operation is a parameter indicating an operation request to the cloud server 20. In this example, “MakeMachines” which is a virtual machine activation request is specified. “MachineTemplate” and “Count” are parameters corresponding to the operation request. FIG. 4 is a diagram illustrating an example of an operation request to the cloud server 20. The operation request includes, for example, MakeKey, which is a request for creating a key pair for SSH (Secure Shell) login to the virtual machine, MakeGroup, which is a request for creating a firewall setting to be assigned to the virtual machine, MakeMachines, which is a request for starting a virtual machine, virtual There are SetIP which is an IP address assignment request to a machine, a virtual machine use request, and the like, which are transmitted from the user terminal 30 to the cloud server 20 together with parameters corresponding to each operation request.

  Returning to FIG. 3, UserID is a user ID that identifies a user corresponding to the user terminal 30 that transmits the message. Time is a time stamp indicating the time when the user terminal 30 transmits a message. The HMAC uses the parameter from the operation request name to the time stamp as the original text (m) of the message, and the original text (m) of the message and the common key (Ks) shared in advance between the cloud server 20 and the user terminal 30. Is a signature value (HMAC value: H (m, Ks)) calculated by a predetermined one-way hash function. A message (Msg (= m || H (m, Ks))) is a parameter in which the original text (m) of such a message and the HMAC value (H (m, Ks)) are concatenated.

The authentication unit 23 includes a first authentication unit 24, a second authentication unit 25, and an authentication information registration unit 26, and authenticates a message transmitted from the user terminal 30.
When the communication unit 22 receives a message from the user terminal 30, the first authentication unit 24 reads the common key (Ks) corresponding to the user ID of the user terminal 30 from the user information storage unit 21, and is included in the message. Based on the original text (m) of the message and the read common key (Ks), an HMAC value is calculated by a predetermined one-way hash function. It is assumed that the one-way hash function algorithm is stored in advance in the storage area of the first authentication unit 24. Then, the calculated HMAC value and the HMAC value included in the message received from the user terminal 30 by the communication unit 22 are compared. If they match, it is determined that authentication is successful, and if they do not match, it is determined that authentication fails.

  The second authentication unit 25 stores the authentication information stored in the user information storage unit 21 in association with the message (Msg) received by the communication unit 22 and the user ID corresponding to the user terminal 30 that transmitted the message. Based on the last request time, the authentication unit determines whether the message received by the communication unit 22 matches the message already transmitted from the user terminal 30 corresponding to the user ID.

  In the present embodiment, the second authentication unit 25 uses the first time indicated by the time stamp (Ts) included in the message received by the communication unit 22 and the user ID corresponding to the user terminal 30 that transmitted the message. The authentication process is performed by comparing the second time indicated by the last request time (Tl) that is the authentication information associated with and stored in the user information storage unit 21. That is, if the first time (Ts) is after the second time (Tl), it is determined that the message received by the communication unit 22 does not match the message already transmitted from the user terminal 30. In this case, the message is a message newly generated based on the new time stamp and the common key corresponding to the user ID, and is likely to be a legitimate message transmitted from a legitimate user. Can be estimated.

  In addition, the second authentication unit 25 determines that the message received by the communication unit 22 is received from the user terminal 30 corresponding to the user ID unless the first time (Ts) is later than the second time (Tl). It is determined that it matches a message that has already been sent. In this case, it can be estimated that there is a high possibility that the message eavesdropped by a third party is a message retransmitted by a replay attack.

  If the second authentication unit 25 determines that the message received by the communication unit 22 does not match the message already transmitted from the user terminal 30 corresponding to the user ID, the authentication information registration unit 26 The included time stamp is stored in the user information storage unit 21 as the last request time.

If the second authentication unit 25 determines that the message received by the communication unit 22 does not match the message already transmitted from the user terminal 30 corresponding to the user ID, the cloud controller unit 27 is included in the message The process according to the operation request to be executed is executed. For example, if the operation request is a virtual machine activation request (Make Machines), the physical machine 10 is activated by the virtual machine specified by the parameter.
The control unit 28 controls each unit included in the cloud server 20.

  The user terminal 30 is connected to the physical machine 10 and the cloud server 20 via a network, and uses the computer resources of the physical machine 10 provided by the cloud system 1. The user terminal 30 includes an input unit such as a keyboard and a mouse, a display unit that is a display, an output unit, a control unit, a storage unit, and the like. The user terminal 30 transmits a computer resource operation request to the cloud server 20 in response to an operation input from the user.

Next, an operation example of the cloud system 1 according to the present embodiment will be described with reference to the drawings. FIG. 5 is a diagram illustrating an operation example of the cloud system 1 according to the present embodiment.
The user terminal 30 generates a message (Msg = m || H (m, Ks)) in response to an input from the user (step S1). The user terminal 30 transmits the generated message (Msg) to the cloud server 20 (step S2). When the communication unit 22 of the cloud server 20 receives the message (Msg) transmitted from the user terminal 30, the control unit 28 transmits an authentication request for the message (Msg) to the authentication unit 23 (step S3). The authentication unit 23 reads user information corresponding to a user ID (UserID) that is a parameter included in the message (Msg) from the user information storage unit 21 (steps S4 and S5). Here, the user information read from the user information storage unit 21 by the authentication unit 23 includes a common key (Ks) and a last request time (Tl).

  The first authentication unit 24 of the authentication unit 23 is a predetermined one based on the original text (m) of the message included in the message (Msg) and the common key (Ks) read from the user information storage unit 21. The HMAC value is calculated using a directional hash function. Then, it is determined whether or not the calculated HMAC value matches the HMAC value included in the message (Msg). Here, if the first authentication unit 24 determines that the calculated HMAC value does not match the HMAC value included in the message (Msg), the first authentication unit 24 determines authentication failure. On the other hand, if it is determined that the calculated HMAC value matches the HMAC value included in the message (Msg), it is determined that the authentication is successful (step S6).

  When the first authentication unit 24 determines that the authentication is successful, the second authentication unit 25 includes the time stamp (Ts) included in the message (Msg) and the last request time read from the user information storage unit 21 in step S5. Compare (Tl). If the time stamp (Ts) is after the last request time (Tl), the second authentication unit 25 determines that the authentication is successful. On the other hand, if the time stamp (Ts) is not after the last request time (Tl), it is determined that the authentication has failed (step S7).

  If it is determined in step S6 and step S7 that the authentication is successful, the authentication information registration unit 26 associates the time stamp (Ts) included in the message (Msg) with the final request time (Tl), and the user information storage unit 21. (Step S8, 9). The authentication unit 23 returns the authentication result in Step S6 and Step S7 (True if the authentication is successful, False if the authentication is unsuccessful) to the control unit 28 (Step S10). If the authentication result by the authentication unit 23 indicates that the authentication is successful, the control unit 28 transmits an operation request included in the message (Msg) to the cloud controller unit 27 (step S11).

  The cloud controller unit 27 executes an operation according to the operation request from the control unit 28 (step S12), and returns a processing result (True if the processing is successful, False if the processing is unsuccessful) (Step S13). If the authentication results in steps S6 and S7 indicate an authentication failure, the control unit 28 transmits the authentication result indicating the authentication failure to the user terminal 30 without performing the processing from step S11 to step S13. . On the other hand, if the authentication results in steps S6 and S7 indicate successful authentication, the processing result received from the cloud controller unit 27 in step S13 is transmitted to the user terminal 30 (step S14).

  FIG. 6 is a diagram illustrating an example of a processing result according to a message transmitted to the cloud server 20 according to the present embodiment. Here, it is assumed that messages indicated by symbols a, b, c, and d are sequentially transmitted to the cloud server 20. In this case, the value “2012-01-01T09: 00: 00Z” is stored at the final request time (Tl) when the message indicated by the symbol a is transmitted. Since the time stamp (Ts) included in the message indicated by the symbol b is “2012-01-01T09: 02: 00Z” and is after the last request time (Tl), it is determined that the authentication is successful. At this time, the value “2012-01-01T09: 02: 00Z”, which is the time stamp of the code b, is stored at the final request time (Tl).

  When the message indicated by symbol a is wiretapped and the message indicated by symbol c is transmitted by a replay attack, the time stamp (Ts) included in this message is “2012-01-01T09: 00: 00Z”. Since it is before the last request time (Tl), it is determined that the authentication has failed. Thereafter, when a message indicated by symbol d is transmitted by a legitimate user, the time stamp (Ts) included in this message is “2012-01-01T09: 03: 00Z”, and the last request time (Tl ) Later, it is determined that the authentication is successful.

  As described above, according to the present embodiment, when the cloud server 20 successfully authenticates the message received from the user terminal 30, the time stamp (Ts) of the message is used as the final request time (Tl). When it is stored in the information storage unit 21 and a new message is received, the time stamp (Ts) of the new message is later than the last request time (Tl) stored in the user information storage unit 21. Only in certain cases, the processing according to the operation request is executed as a successful authentication. Thereby, when there is a replay attack by a third party, it is possible to prevent the processing from being executed as an authentication failure.

  In this way, for example, an operation request that is a virtual machine activation request by a legitimate user is intercepted by a third party, and a large number of virtual machine activation requests are retransmitted to the cloud server 20 by the third party, A replay attack that starts a large number of virtual machines can be prevented. In other words, it is possible to prevent an excessive charge from being made to a legitimate user due to such a replay attack, or an excessive strain on the resources of the cloud server 20 or the physical machine 10. In addition, for example, an operation request that is a virtual machine stop request by a legitimate user is eavesdropped by a third party, and the third party resends the virtual machine stop request to the cloud server 20. A replay attack that unintentionally stops the service provided using the cloud server 20 can be prevented.

  Further, for example, if the communication path between the user terminal 30 and the cloud server 20 is encrypted using SSL (Secure Socket Layer) or the like, wiretapping in the communication path can be prevented. However, if the tool that transmits a message from the user terminal 30 to the cloud server 20 is malware, and the message is transmitted to the third party at the same time as the message is transmitted to the cloud server 20, the message is It can be stolen and replayed. Alternatively, for example, a message transmitted to the cloud server 20 may be stolen by a phishing scam and the message may be stolen and a replay attack may be performed. On the other hand, according to the present embodiment, when a stolen message is retransmitted, the time stamp (Ts) included in the retransmitted message is already stored as the last request time (Tl). If a failure occurs and there is a replay attack, the process can be prevented from being executed.

Further, since the user terminal 30 only needs to transmit a message including the time at its own terminal as a time stamp to the cloud server 20, it is not necessary to manage new information such as a sequence number.
Further, since the user terminal 30 does not need to perform communication such as acquisition of nonce by the challenge / response method, the number of communication does not increase for countermeasures against the replay attack.
In addition, according to the present embodiment, in order to detect a replay attack using a time stamp, the parameter of the message is increased with respect to an existing system that makes an operation request with a message that includes the time stamp, A function for efficiently preventing a replay attack can be implemented without changing the communication sequence.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. Since the configuration of the cloud system 1 according to this embodiment is the same as that of the first embodiment, the characteristic points of this embodiment will be described. According to the first embodiment, a replay attack can be prevented. However, when a plurality of messages are transmitted from the user terminal 30 of a legitimate user to the cloud server 20 at the same time, only the first message is successfully authenticated. Subsequent messages result in authentication failure. For example, in the first embodiment, since the time stamp is stored in seconds, as shown in FIG. 7, when a plurality of messages are transmitted at the same time within one second, the second and subsequent times. The sent message fails authentication. For example, when message transmission processing from the user terminal 30 to the cloud server 20 is automated using a script, a tool, or the like, a plurality of messages may be transmitted within one second. Even if the time stamp format is generated in milliseconds, if a plurality of messages are transmitted within 1 millisecond, authentication fails similarly.

  Therefore, the communication unit 22 according to the present embodiment receives a message including a plurality of operation requests from the user terminal 30. For example, the user terminal 30 transmits, to the cloud server 20, one message in which a message indicating a plurality of operation requests is nested as an item such as “Next”. For example, "https://a.com/?operation=...&Param1=...&Next=" operation = ... & Param1 = ... & Next = "operation = ... & Param1 = ..." " As described above, a nested statement is used, so that a plurality of operation requests are included in one message.

  In this case, the time stamp may be added for each of a plurality of operation requests included in one message, or one time stamp may be added to a plurality of operation requests. When a time stamp is added for each of a plurality of operation requests included in one message, the second authentication unit 25 uses the time stamp (Ts) as long as the message included in the message is processed. The information is not stored in the information storage unit 21. Thereby, the process with respect to the several operation request contained in one message can be performed. Alternatively, when one time stamp is added to a plurality of operation requests, the second authenticating unit 25 performs a comparison process between the time stamp and the last request time only to determine whether or not authentication is possible.

If the second authentication unit 25 determines that the message received by the communication unit 22 does not match the message already transmitted from the user terminal 30 corresponding to the user ID, the cloud controller unit 27 is included in the message A process corresponding to a plurality of operation requests is executed.
In this way, the user terminal 30 transmits a plurality of operation requests to the cloud server 20 within a limited time (for example, 1 second) by including a plurality of operation requests in one message, and executes them. It becomes possible to make it.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. Since the configuration of the cloud system 1 according to this embodiment is the same as that of the first embodiment, the characteristic points of this embodiment will be described. In the first embodiment, a time stamp (Ts) is used as authentication information for authenticating whether the message transmitted from the user terminal 30 matches the message already transmitted from the user terminal 30 corresponding to the user ID. An example of applying is described. On the other hand, in this embodiment, an HMAC value that is a signature value based on a parameter included in a message is applied as authentication information. Since the HMAC value is generated based on the original text (m) of the message including the time stamp (Ts), the replay attack can also be detected by comparing the HMAC value. That is, when the same message is transmitted a plurality of times, since the HMAC value included in the message is the same, the second and subsequent messages associated with the same HMAC value may have been transmitted by a replay attack. Can be estimated to be high.

  FIG. 8 is a diagram illustrating a data example of user information stored in the user information storage unit 21 in the present embodiment. The user information includes information in which a common key (Ks) and a list of HMAC values (H_list) are associated with each other for each user ID. The list of HMAC values (H_list) includes one or more HMAC values received from the user terminal 30 of the user.

  The second authentication unit 25 stores the first HMAC value included in the message received by the communication unit 22 and the user ID corresponding to the user terminal 30 that transmitted the message in the user information storage unit 21. Authentication processing is performed by comparing the second HMAC value, which is authentication information that has been registered. That is, if the first HMAC value matches the second HMAC value, the second authentication unit 25 indicates that the message received by the communication unit 22 has already been transmitted from the user terminal 30 corresponding to the user ID. If the first HMAC value does not match the second HMAC value, the message received by the communication unit 22 does not match the message already transmitted from the user terminal 30 corresponding to the user ID. Is determined.

  FIG. 9 is a diagram illustrating an operation example of the cloud system 1 according to the present embodiment. Steps S20 to S23 are the same as steps S1 to S4 in the first embodiment. The first authentication unit 24 reads user information including a list of HMAC values from the user information storage unit 21 (step S24). The first authentication unit 24 performs the same HMAC authentication process as step S6 in the first embodiment (step S25). The second authentication unit 25 determines whether the HMAC value included in the message (Msg) received from the user terminal 30 is included in the list of HMAC values read from the user information storage unit 21. The second authentication unit 25 determines that the authentication has failed if the HMAC value included in the message (Msg) received from the user terminal 30 is included in the list of HMAC values read from the user information storage unit 21. If the HMAC value included in the message (Msg) received from the user terminal 30 is not included in the list of HMAC values read from the user information storage unit 21, it is determined that the authentication is successful (step S26).

  If it is determined in step S25 and step S26 that the authentication is successful, the authentication information registration unit 26 adds the HMAC value (H (m, Ks)) included in the message (Msg) to the list of HMAC values, and the user information It memorize | stores in the memory | storage part 21 (step S27, 28). The processing from step S29 to step S33 is the same as that from step S10 to step S14 in the first embodiment.

FIG. 10 is a diagram illustrating an example of a processing result according to a message transmitted to the cloud server 20 according to the present embodiment. In this case, the time stamp (Ts) value included in the message indicated by the symbols a, b, c, and d is the same, but the value of Operation is different among the parameters included in the original text (m) of the message. Thereby, since the HMAC values corresponding to the messages indicated by the symbols a, b, c, and d are different values, it is determined that the HMAC value is not included in the list of HMAC values, and authentication is successful.
FIG. 11 is a diagram illustrating another example of the processing result according to the message transmitted to the cloud server 20 according to the present embodiment. Here, since the HMAC value of the message indicated by the symbol a and the HMAC value of the message indicated by the symbol b are different, it is determined that the authentication is successful. Since the HMAC value of the message indicated by symbol c and the HMAC value of the message indicated by symbol a are the same, and the HMAC value of the message indicated by symbol d and the HMAC value of the message indicated by symbol b are the same, authentication failure The process corresponding to the operation request is not executed.

As described above, according to the present embodiment, the cloud server 20 stores the list of HMAC values included in the message transmitted from the user terminal 30 in the user information storage unit 21, and the user server 30 starts a new list. If a message is transmitted, it is determined whether or not the HMAC value included in the message is included in the list of HMAC values stored in the user information storage unit 21. The processing to do is not executed. Thereby, since the HMAC value included in the message by the replay attack is already stored in the user information storage unit 21 of the cloud server 20, the processing corresponding to the message can be prevented from being executed, and the replay attack can be performed. Can be prevented.
According to this, even if the messages have the same time stamp added as compared to the first embodiment, the processing can be executed if other parameters are different.
Note that in this embodiment as well, a plurality of operation requests may be included in one message, as in the second embodiment.

  Note that a program for realizing the function of the processing unit in the present invention is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed to authenticate the message. You may go. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer system” includes a WWW system having a homepage providing environment (or display environment). The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

DESCRIPTION OF SYMBOLS 1 Cloud system 10 Physical machine 20 Cloud server 21 User information storage part 22 Communication part 23 Authentication part 24 1st authentication part 25 2nd authentication part 26 Authentication information registration part 27 Cloud controller part 28 Control part 30 User terminal

Claims (8)

A user ID for identifying the user, and authentication information for determining whether a message transmitted from the user terminal corresponding to the user ID matches a message already transmitted from the user terminal corresponding to the user ID; A user information storage unit that stores user information associated with
A receiving unit for receiving a message including a time stamp indicating a time at which the user terminal transmits the message from the user terminal;
Based on the message received by the receiving unit and the authentication information stored in the user information storage unit in association with the user ID corresponding to the user terminal that transmitted the message, the receiving unit An authentication unit that performs an authentication process for determining whether the message received by the user terminal matches the message already transmitted from the user terminal corresponding to the user ID;
When the authentication unit determines that the message received by the receiving unit does not match the message already transmitted from the user terminal corresponding to the user ID, the authentication information corresponding to the message is changed to the user information. An authentication information registration unit to be stored in the storage unit;
An authentication device comprising: The authentication information is a time stamp,
The authentication unit stores the first time indicated by the time stamp included in the message received by the reception unit and the user ID corresponding to the user terminal that transmitted the message in the user information storage unit. The authentication apparatus according to claim 1, wherein the authentication process is performed by comparing a second time indicated by a time stamp as the authentication information. If the first time is later than the second time, the authentication unit does not match the message already received from the user terminal corresponding to the user ID. If the first time is not later than the second time, the message received by the receiving unit is determined to match the message already transmitted from the user terminal corresponding to the user ID. The authentication device according to claim 2, wherein: The authentication information is a signature value based on a parameter included in the message;
The receiving unit receives a message including the signature value from the user terminal;
The authentication unit is stored in the user information storage unit in association with a first signature value included in the message received by the reception unit and a user ID corresponding to the user terminal that transmitted the message. The authentication apparatus according to claim 1, wherein the authentication process is performed by comparing a second signature value that is the authentication information. If the first signature value matches the second signature value, the authentication unit matches the message already received from the user terminal corresponding to the user ID if the message received by the receiving unit If the first signature value does not match the second signature value, the message received by the receiving unit matches the message already transmitted from the user terminal corresponding to the user ID. The authentication apparatus according to claim 4, wherein it is determined that the authentication is not performed. The receiving unit receives the message including a plurality of operation requests;
The authentication device
If the authentication unit determines that the message received by the receiving unit does not match the message already transmitted from the user terminal corresponding to the user ID, it corresponds to a plurality of operation requests included in the message. The authentication apparatus according to any one of claims 1 to 5, further comprising an execution unit that executes processing. A user ID for identifying the user, and authentication information for determining whether a message transmitted from the user terminal corresponding to the user ID matches a message already transmitted from the user terminal corresponding to the user ID; Is an authentication method of an authentication device including a user information storage unit that stores user information associated with
Receiving from the user terminal a message including a time stamp indicating the time when the user terminal transmitted the message;
Based on the received message and the authentication information stored in the user information storage unit in association with the user ID corresponding to the user terminal that transmitted the message, the received message is the user Performing an authentication process for determining whether or not the message already transmitted from the user terminal corresponding to the ID matches,
If it is determined that the received message does not match the message already transmitted from the user terminal corresponding to the user ID, the authentication information corresponding to the message is stored in the user information storage unit;
An authentication method comprising: A user ID for identifying the user, and authentication information for determining whether a message transmitted from the user terminal corresponding to the user ID matches a message already transmitted from the user terminal corresponding to the user ID; In the computer of the authentication device including a user information storage unit that stores user information associated with
Receiving from the user terminal a message including a time stamp indicating the time when the user terminal transmitted the message;
Based on the received message and the authentication information stored in the user information storage unit in association with the user ID corresponding to the user terminal that transmitted the message, the received message is the user Performing an authentication process for determining whether or not the message already transmitted from the user terminal corresponding to the ID matches,
If it is determined that the received message does not match the message already transmitted from the user terminal corresponding to the user ID, the authentication information corresponding to the message is stored in the user information storage unit;
A program that executes

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