JP6757988B2 - Information security method and information security system using key synchronization - Google Patents

Description

The present invention relates to an information security technique, and more particularly to a method of security of information that requires confidentiality by using key synchronization.

With the development of electronic commerce, many commerce is being carried out not only offline but also online, and for this reason, confidential personal information such as credit cards is transmitted and used online at any time.

In particular, recently, unlike the existing procedure that requires the authentication procedure of the bank or card company at each payment, if you register the credit card information, you can make an electronic payment without having to perform a separate authentication procedure. The system is coming out. Typical examples are Google Wallet (registered trademark) and Apple Pay (registered trademark).

On the other hand, as a side effect of such simplified electronic commerce, information security problems such as leakage of personal information have emerged greatly, and along with this, various security means have been researched and searched.

As part of such a process, PCI-DSS (Payment Card Industry Data Security) is a security-related standard for the credit card industry to securely protect credit card information and transaction information of card members handled by payment agents of member stores. Standard).

The PCI-DSS clearly states that protective measures must be taken when storing, calculating, and transmitting card information, but it is recognized as a technology that satisfies the requirements stipulated in such PCI-DSS. One of the things that has been done is tokenization technology.

Tokenization technology is a technology that replaces existing credit card information and the like with digital tokens in offline and online commerce. The tokenization technique will be described in more detail with reference to FIG.

FIG. 1 is a configuration diagram showing the configuration of the existing tokenization technology.

Referring to FIG. 1, the terminal of the store, which is the transmission end 10 for transmitting the credit card information, encrypts the credit card information and transmits it to the token server to request the generation of the token (a). In response to such a request, the token server 20 generates a token corresponding to the credit card information, matches the token with the credit card information, stores the token in the token storage 30, and transmits the generated token to the transmission end 10 ( b). The transmission end 10 receives such a token and sends it to the server of the card company which is the reception end 40 (c), and the reception end 40 which receives this requests the token server 20 to decrypt the token in order to confirm the credit card information. (D). The token server 20 decodes the credit card information based on the stored matching information and notifies the receiving end 40 (e).

However, since such an existing tokenization technology is a method of generating a digital token on the token server and restoring it to the original information again, it is necessary to separately handle sensitive confidential information in the process of exchanging data with the token server. It is normal to take the encryption measures of.

In addition, since all confidential information and digital tokens are stored on the token server, security risks are concentrated on the token server, and a high level of security such as authentication and authority management is required for the connection to the token server. There is.

An object of the present invention for solving the above-mentioned problems is to provide an information security method using key synchronization executed on a user terminal.

Another object of the present invention for solving the above-mentioned problems is to provide an information security method using key synchronization executed by a service providing server.

Yet another object of the present invention for solving the above-mentioned problems is to provide an information security method using key synchronization.

The information security method using key sharing according to one aspect of the present invention for achieving the above object is executed by the user terminal, and at the stage of receiving a request for processing confidential information, the key pool of the user terminal (key pool). ) Includes a step of extracting a key for generating a token corresponding to confidential information and a step of using the extracted key to generate a token corresponding to confidential information.

Here, the key pool of the user terminal may store the key issued by the key server.

Here, the key pool of the user terminal may be composed of the key derived by applying the eigenvalue of the user terminal to the key issued to the service providing server linked with the user terminal.

Here, as a stage before or after the stage where the user terminal uses the extracted key to generate a token corresponding to confidential information, the key pool of the user terminal is updated by the extracted key. Further steps can be included.

Here, at the stage of updating the key pool of the user terminal with the extracted key, the extracted key is excluded from the key pool of the user terminal or the presence / absence of extraction is displayed, and the extracted key is selectively extracted. The key generated by using it can be saved in the key pool of the user terminal.

Here, after the stage where the user terminal uses the extracted key to generate the token corresponding to the confidential information, the stage where the generated token and the key-related information are transmitted to the service providing server linked with the user terminal. Further can be included.

The information security method using key synchronization according to another aspect of the present invention for achieving the above object is executed by the service providing server, and is received at the stage of receiving the token and the key-related information from the user terminal. It includes a step of extracting the key by the key-related information from the key pool of the service providing server using the key-related information and a step of recovering the received token to the confidential information by using the extracted key.

Here, in the key pool of the service providing server, the key issued from the key server (keyserver) can be stored.

Here, the key pool of the user terminal may be composed of the key derived by applying the unique value of the user terminal to the key issued to the service providing server.

Here, in the stage of restoring the received token to confidential information using the extracted key, the extracted key and key-related information are used to generate a key synchronized with the user terminal. The received token can be restored to confidential information using the synchronized key.

Here, a step of updating the key pool of the service providing server can be further included as a step before or after the step of restoring the token received by using the extracted key to the confidential information.

In the information security method using key synchronization according to another aspect of the present invention for achieving the above object, the key server issues a key to a user terminal and a service providing server, and the user terminal is a confidential information. At the stage of extracting the key for token generation corresponding to confidential information from the key pool of the user terminal in response to the processing request, the user terminal uses the extracted key to generate the token corresponding to the confidential information. The stage, the stage where the user terminal transmits the generated token and key-related information to the service providing server, the stage where the service providing server uses the transmitted key-related information to extract the key from the key pool of the service providing server, And the service providing server includes the step of recovering the confidential information from the token transmitted from the user terminal by using the key extracted from the key pool of the service providing server.

Here, the key pool of the user terminal may be composed of the key derived by applying the unique value of the user terminal to the key issued to the service providing server.

Here, as a stage before or after the stage where the user terminal uses the extracted key to generate a token corresponding to confidential information, the user terminal uses the key extracted from the key pool of the user terminal. It can further include the step of updating the key pool of the personal terminal.

Here, the stage of updating the key pool of the user terminal is generated by excluding the extracted key from the key pool of the user terminal or displaying the presence / absence of extraction and using the selectively extracted key. The key can be saved in the key pool of the user terminal.

Here, at the stage where the service providing server recovers the confidential information from the token transmitted from the user terminal by using the key extracted from the key pool of the service providing server, the extracted key and the key-related information are used. It can be used to generate a key that is synchronized with the user terminal and restore the received token using the synchronized key.

Here, before or after the stage where the service providing server recovers confidential information from the transmitted token by using the key extracted from the service providing server's key pool, the service providing server is the service providing server. It can include additional steps to update the key pool.

When the information security method using the key synchronization according to the present invention as described above is used, tokens are generated and decrypted at the transmitting and receiving ends without going through the token server, so that the security risk can be dispersed. it can.

In addition, even if the key is exposed on the key server, tokens are exchanged only at the transmission / reception end, so confidential information is not exposed, and the key pool can be replaced to repair and inspect equipment relatively easily. There is.

In addition, key synchronization eliminates the need to transfer the key itself except when the key is issued. For this reason, even if key-related information is leaked during the transmission process from the user terminal to the service providing server, the key cannot be known without the key pool, making it easier to deal with security issues during the transmission process. can do.

A block diagram showing the configuration of existing tokenization technology. The block diagram which shows the information security method using the key synchronization which concerns on embodiment of this invention. FIG. 3 is a configuration diagram for explaining a transmitting end device and a receiving end device that execute an information security method using key synchronization according to an embodiment of the present invention. The flowchart which shows the information security method using the key synchronization executed in the user terminal which concerns on embodiment of this invention. The flowchart which shows the information security method using the key synchronization executed in the service providing server which concerns on embodiment of this invention. The sequence diagram which shows the information security method using the key synchronization which concerns on embodiment of this invention.

Although the present invention can be modified in various ways and can have various examples, specific examples will be illustrated in the drawings and described in detail in detail. However, this is not intended to limit the invention to any particular embodiment, but should be understood to include all modifications, equivalents or alternatives contained within the ideas and technical scope of the invention. When each drawing is described, similar reference numerals are given to similar components for description.

Terms such as first, second, A, and B can be used to describe a variety of components, but the components are not limited by the terms. The term is used only to distinguish one component from the other. For example, without departing from the scope of rights of the present invention, the first component can be named as the second component, and similarly, the second component can be named as the first component. The terms and / or include any combination of a plurality of related described items or a plurality of related described items.

When it is mentioned that one component is "connected" or "connected" to another component, it may be directly connected or connected to another component. It should be understood that there may be other components in between. On the other hand, when it is mentioned that one component is "directly linked" or "directly connected" to another component, it should be understood that there is no other component in between.

The terms used in this application are used solely to describe a particular embodiment and are not intended to limit the invention. A singular expression includes multiple expressions unless it means that they are explicitly different in context. In this application, terms such as "including" or "having" seek to specify the existence of features, numbers, stages, actions, components, parts or combinations thereof described herein. It should be understood that it does not preclude the existence or addability of one or more other features or numbers, stages, actions, components, parts or combinations thereof.

Unless otherwise defined, all terms used herein include technical or scientific terms and have the same meaning as commonly understood by those with ordinary knowledge in the technical field to which the invention belongs. Have. Terms such as those defined in commonly used dictionaries should be construed to have meanings consistent with those in the context of the relevant technology and are ideal or excessive unless expressly defined in this application. Is not interpreted as a formal meaning.

Hereinafter, a detailed description will be given with reference to the drawings attached with preferred embodiments according to the present invention.

FIG. 2 is a configuration diagram showing a configuration for an information security method using key synchronization.

With reference to FIG. 2, the present invention may include a transmitting end 100, a key server 200, and a receiving end 300.

First, the user terminal, which is the transmitting terminal 100, plays a role of generating a token from confidential information by utilizing the key issued from the key server 200 and transmitting the token and key-related information to the receiving terminal 300. Here, the user terminal may mean a smartphone or tablet PC, a laptop computer, a computer, a smart home appliance, a POS terminal, or a device that provides an IoT service on which a card payment app is driven, but is limited thereto. It may be a variety of communication devices that require the handling of confidential information.

Further, the key server 200 is a server device capable of short-distance or long-distance communication using a wireless network, generates and stores a key, and issues the generated key to the transmitting end 100 and the receiving end 300. can do.

The service providing server of the receiving end 300 may be, but is not limited to, various server devices connected to a wireless network such as a server of a credit card company and an online server providing an IoT service, but the transmitting end is not limited to this. It is possible to receive token and key related information from 100, interpret the token based on this, and confirm confidential information.

For example, the transmitting end 100 may be a card payment machine owned by a card member store, and the receiving end 300 may be a server of a card company that performs card payment.

Specifically, the business owner of the card member store can use the transmission end 100 to make a payment according to the customer's payment request. In such a process, it is necessary to collect the customer's payment information including the card number and notify the server of the card company.

When a payment request comes in order to execute this, the transmitting end 100 generates a token by using one of the keys issued in advance (a) from the key server 200 and the customer's payment information to create a key pool. Update (b). After that, the token is transmitted to the receiving end 300 together with the key-related information used for generating the token (c). After receiving the key-related information and the token, the receiving end 300 extracts the key from the key pool by utilizing the key-related information. Using the key extracted in this way, the token can be restored to the customer's payment information again and the key pool can be updated (d), and the card company can perform the payment business using the restored payment information. ..

FIG. 3 is a configuration diagram for explaining a device at a transmitting end and a receiving end that executes an information security method using key synchronization according to an embodiment of the present invention.

The roles of the transmitting end 100 and the receiving end 300 will be described in more detail with reference to FIG.

The transmission end 100 may include a key pool 110, a key extraction unit 120, and a token generation unit 130.

The key pool 110 can be a kind of storage composed of one or more keys transmitted from the key server 200. Further, when the key is extracted, the key pool 110 can update the key information for saving the new key by reflecting the extracted information. The specific update process will be described in detail later.

The key extraction unit 120 can extract the key used when generating the token from the key pool 110. The key extracted in this way is used to generate a token in the token generator.

The token generation unit 130 can generate a token corresponding to the confidential information by using the key extracted by the key extraction unit. Here, the token is an alternative means of confidential information, and even if it is leaked to the outside, the confidential information is not known, so it becomes meaningless information.

In this way, each information about the key extracted by the key extraction unit 120, that is, the key-related information and the token generated by the token generation unit 130 are transmitted to the receiving end 300.

The receiving end 300 may include a key pool 310, a key extracting unit 320, and an information restoring unit 330.

The key pool 310 is a kind of storage composed of the keys transmitted from the key server 200, and can share a common key with the key pool 110 at the transmission end 100, but has different keys from each other. You can also do it. The key information can be updated in the same manner as at the transmission end 100.

The key extraction unit 320 plays a role of extracting a key from the key pool 310 by using the key-related information transmitted by the transmission end 100, and similarly executes a function equivalent to that of the key extraction unit 120 at the transmission end 100. ..

The information restoration unit 330 can restore confidential information by using the token received at the transmission end 100 and the key extracted by the key extraction unit.

FIG. 4 is a flowchart of an information security method using key synchronization performed on the user terminal.

Referring to FIG. 4, the user terminal first receives the confidential information processing request (S110).

Confidential information can also mean personal information that requires confidentiality, such as the user's credit card number, account number, financial information, medical records, criminal records, credential records, stock transactions and lending records. It is not limited to this. Here, the request for processing confidential information may be requested by, for example, an application driven by the user terminal by the user's electronic commerce, or may be requested by a card terminal in the offline sales floor, but is limited to this. is not.

Here, the user terminal can have an eigenvalue that can be distinguished from other user terminals, but the eigenvalue is the only one that is distinguished from the user terminal's identification code (ID) and other user terminals. Can mean the symbol possessed by. It is also possible to have a key pool ID and a transmission counter. The ID of the key pool is a unique identification code of the key pool that the user terminal has to distinguish it from other user terminals, and the transmission counter may mean a number or a symbol used for key synchronization.

A key for generating a token corresponding to confidential information is extracted from the key pool of the user terminal (S120). Here, the key pool can store the key issued by the key server. At this time, the meaning issued from the key server does not necessarily mean that the key is received directly from the key server, and the key issued by the key server may be held at the time of manufacturing the user terminal. , The key may be stored in the key pool of the user terminal through a separate issuance process after manufacturing.

In addition, the key server can give a certain expiration date to the issued key to improve security, prevent the already issued key from being used after the expiration date, and issue a new key. You can also do it.

Here, the key pool of the user terminal may be composed of the key derived by applying the unique value of the user terminal to the key issued to the service providing server. Here, various encryption algorithms can be used as the method for deriving the key, and specifically, for example, a TDEA (Triple data encryption algorithm) encryption algorithm can be applied.

By using such a configuration, even if the service providing server and the user terminal have different key pools, the service providing server uses the key extracted from its own key pool and the user terminal issues the key from the key server. It is possible to derive the received key. That is, the key used by the service providing server can be synchronized with the key of the user terminal.

Therefore, it reduces the difficulty of the user terminal and the service providing server constantly synchronizing the key pool with each other, and reduces the problem that the user providing server has to maintain and manage a separate key pool for each user terminal. be able to. Further, unlike the service providing server, the user terminal can be used as it is without extracting a key from its own key pool and performing a separate calculation, so that the load on the user terminal is not large.

However, it is not always necessary to have such a configuration, and it does not mean that the key server provides the same key to the user terminal and the service providing server.

In addition, the process in which the key server issues the key and transmits the key to the user terminal and the service providing server can be performed by adopting a secure channel or data encryption in order to prevent the risk of key leakage.

Here, the keys required for token generation may be extracted from the key pool in a preset order, or the keys saved earlier may be extracted. It is also possible to extract the key corresponding to the transmission counter by using the transmission counter of the user terminal. At this time, the transmission counter is a number that increases by one each time the key is used to generate the token, and serves to distinguish the currently used key from the key stored in the key pool, and is a service providing server. It can be used as a means of synchronizing the key with the service providing server by being transmitted together when transmitting the token to.

However, this is just an example, and a variety of other means can be used to synchronize the key with the service provider.

The extracted key is used to generate a token corresponding to the confidential information (S130). Here, for example, a random number generator (RNG; Random Number Generator) or an encryption method (encryption) using a key may be applied to the token generation. However, even in this case, it goes without saying that the confidential information is not known from the token, and the different confidential information must be generated by different tokens, and it is preferable that two or more confidential information do not exist in the same token.

It is also advantageous to generate sensitive information attributes, that is, tokens that have the same attributes as the length and type of data for compatibility with existing systems. For such same attribute maintenance, specifically, for example, an attribute maintenance encryption method (FRE; Format Preserving Encryption) can be applied.

The key pool can be updated with the extracted key before or after the stage (S130) in which the user terminal uses the extracted key to generate a token corresponding to the confidential information.

Here, the method of updating the key pool can exclude the extracted key from the key pool or display the presence or absence of extraction, and the key generated by using the selectively extracted key is used as the key pool. Can be saved in. Here, various methods can be used to generate the key using the extracted key. For example, one-way encryption or a hash function can be used, and the transmission possessed by the user terminal in advance. You can use the counter together. At this time, the generated key is a key to be used in the next transmission, is stored in the key pool, and can be stored so that the transmission counters correspond to each other.

To explain more specifically with an example, it is also possible to generate a key by unidirectionally encrypting the extracted key as many times as the number of transmission counters. In such a configuration, the service providing server sets the transmission counter. It can be used to derive the key used by the user terminal.

Further, when generating the key, the number of keys in the key pool of the user terminal after the key extraction may be less than or equal to the preset number, or it can be generated at each update.

In this way, when the user terminal is configured to directly generate and use the key, it is possible to reduce the difficulty of receiving the key from the key server and synchronizing with the service providing server.

However, it is not always necessary to follow this method, and it is possible to update by receiving the key issued from the key server in the key pool of the service providing server and the corresponding key.

In addition, the token and key-related information generated after the token is generated (S130) can be transmitted to the service providing server (S140). Here, the key-related information can include information on the location and method from which the key used for extraction and token generation can be confirmed or derived from the key pool, for example, an eigenvalue or a service providing server held by the user terminal. Can include a synchronization symbol to derive the synchronization key with.

FIG. 5 is a flowchart of an information security method using key synchronization executed by the service providing server.

Referring to FIG. 5, the service providing server first receives the token and key-related information from the user terminal (S210). Here, the key-related information can include information on the location and method from which the key used for extraction and token generation can be confirmed or derived from the key pool, for example, an eigenvalue or a service providing server held by the user terminal. Can include a synchronization symbol to derive the synchronization key with.

The key is extracted from the key pool of the service providing server using the received key-related information (S220). Here, the key pool of the service providing server can store the key issued by the key server.

Here, a secure channel or data encryption can be adopted when the key of the key server is issued.

Also, at this time, in the key pool setting of the service providing server, a sufficient number of keys must be included so that one key does not tokenize or detokenizaion two or more confidential information. Is advantageous.

Here, the method of extracting the key can extract the key corresponding to the key pool of the user terminal by using the key-related information. Specifically, it is possible to obtain the eigenvalue of the user terminal from the key-related information and extract the corresponding key. Corresponding can mean a case where the unique value of the user terminal can be applied to the extracted key and the corresponding user terminal can derive the key issued from the key server.

The token received by using the extracted key is restored to confidential information (S230). Specifically, the extracted key and the key-related information are used to generate a key synchronized with the user terminal, and the synchronized key is used to confidential the received token. It can be restored to information.

For example, first, the eigenvalue of the user terminal (for example, the identification code of the user terminal) is obtained from the key-related information, and this value is applied to the extracted key for conversion. Through such conversion, the user terminal can obtain the key issued by the key server. Here, various encryption algorithms can be used as the conversion method, and specifically, for example, the TDEA encryption algorithm can be applied.

However, if the user terminal uses the key issued by the key server as it is, it can be restored as it is, but if the key is generated and used by yourself, the key used for tokenization is unknown. .. Therefore, the information used by the user terminal for generating the key can be obtained through the key-related information, and the key used by the user terminal for tokenization can be derived by using this information. Specifically, after extracting a synchronization symbol such as a transmission counter from the key-related information, the key used by the user terminal is obtained by using the same method as the method in which the user terminal generated the key in the above. Can be derived.

In addition, the key pool can be updated before or after the stage (S230) of restoring the received token to confidential information using the extracted key (S240).

Here, when the update is made, if the expiration date of the extracted key has passed, or if the transmission counter in the received key-related information exceeds a certain number of times, there is a security risk in the user terminal or service providing server. May be detected.

Further, in such a case, the update method may request the key server to issue a key, issue the key to the service providing server, and issue a new key to the user terminal again.

FIG. 6 is a sequence diagram relating to an information security method using key synchronization, which is executed by interacting with a key server, a user terminal, and a service providing server.

The overall interaction relationship between the key server, the user terminal, and the service providing server will be described with reference to FIG.

First, the key server issues a key to the user terminal and the service providing server (S300-1, S300-2). As a result, the user terminal and the service providing server have a key pool composed of the issued keys (S310-1, S310-2).

Here, the key pool of the user terminal may be composed of the key derived by applying the eigenvalue of the user terminal to the key issued to the service providing server.

When a request for processing confidential information is generated at the user terminal, the user terminal extracts a key for generating a token corresponding to the confidential information from the key pool of the user terminal (S320).

The user terminal uses the extracted key to generate a token corresponding to the confidential information (S330).

Further, before or after the token generation (S330), the user terminal can update the key pool of the user terminal with the key extracted from the key pool of the user terminal (S340). Here, the extracted key is excluded from the key pool of the user terminal or the presence / absence of extraction is displayed, and the key generated by using the selectively extracted key is saved in the key pool of the user terminal. be able to.

The user terminal transmits the generated token and key-related information to the service providing server (S350).

The service providing server extracts the key from the key pool set in the service providing server by using the key-related information transmitted (S360).

The service providing server recovers confidential information from the token transmitted from the user terminal by using the key extracted from the key pool set in the service providing server (S370). More specifically, the extracted key and the key-related information are used to generate a key synchronized with the user terminal, and the synchronized key is used to restore the received token. Can be done.

The key pool of the service providing server can be updated before or after the stage of recovering the confidential information (S370) (S380).

According to the embodiment of the present invention described above, the service providing server can recover the confidential information from the transmitted token by using the key extracted from the key pool set in the service providing server. Since tokens are generated and decrypted at the transmitting and receiving ends without going through the token server, security risks can be distributed.

In addition, even if the key is exposed on the key server, tokens are exchanged only at the transmission / reception end, so confidential information is not exposed, and the key pool can be replaced to repair and inspect equipment relatively easily. There is.

Further, due to key synchronization, transmission of the key itself is unnecessary except when the key is issued. For this reason, even if the key-related information is leaked in the transmission process from the user terminal to the service providing server, since the key is not known, it is possible to more easily deal with the security problem in the transmission process.

The configurations of the user terminal of the transmitting terminal 100, the key server 200, and the service providing server of the receiving terminal 300 according to the above-described embodiment of the present invention have been described by enumerating them in each configuration unit for convenience of explanation. At least two of them can be combined into one component, or one component can be divided into multiple components to perform functions, and such grooved parts can be integrated and separated. The example is also included in the scope of rights of the present invention as long as it does not deviate from the essence of the present invention.

Further, the operation of the service providing server of the user terminal of the transmitting terminal 100, the key server 200, and the receiving terminal 300 according to the embodiment of the present invention shall be embodied in a computer-readable program or code on a computer-readable recording medium. Is possible. Computer-readable recording media include all types of recording devices in which data that can be read by a computer system is stored. In addition, a computer-readable recording medium can be distributed to a computer system connected to a network, and a computer-readable program or code can be stored and executed in a distributed manner.

Although the above description has been made with reference to preferred embodiments of the present invention, skilled artisans in the art will use the present invention within the scope of the ideas and areas of the invention described in the claims below. You can see that it can be modified and changed in various ways.

10: User terminal 20: Token server 30: Token storage 40: Service providing server 100: Transmission terminal 110: Key pool 120: Key extraction unit 130: Token generation unit 200: Key server 300: Reception terminal 310: Key pool 320 : Key extraction unit 330: Information restoration unit

Claims (5)

In the information security method executed by the user terminal,
At the stage of receiving a request to process confidential information,
The stage of extracting the key stored in the key pool of the user terminal and
At the stage of generating a token corresponding to the confidential information using the extracted key, and
Including the step of transmitting the token and key related information to the service providing server.
In the key pool of the user terminal, the second key derived by applying the eigenvalue of the user terminal to the first key is initially stored.
The first key is a key issued by the key server to the service providing server.
As a stage before or after the stage of generating the token
The stage of generating the third key by encrypting the second key using a transmission counter, and
Including the step of updating the key pool of the user terminal by storing the third key in the key pool of the user terminal.
The transmission counter is a number that increases each time the token is generated and transmitted.
An information security method in which the key-related information includes a transmission counter and unique values of the user terminal. The stage of generating the third key is
The information security method according to claim 1, wherein the second key is unidirectionally encrypted for the number of times of the transmission counter to generate the third key. The stage of updating the key pool of the user terminal is
The information according to claim 1, further comprising a step of excluding the key extracted from the key pool of the user terminal from the key pool of the user terminal or displaying the presence or absence of extraction. Security method. In the information security method for sending and receiving confidential information between the user terminal and the service providing server,
When the key server issues the key to the user terminal and the service providing server,
The stage where the user terminal extracts the key stored in the key pool of the user terminal in response to a request for processing confidential information, and
A step in which the user terminal uses a key extracted from the key pool of the user terminal to generate a token corresponding to the confidential information.
At the stage where the user terminal transmits the token and key-related information to the service providing server,
When the service providing server receives the token and the key-related information from the user terminal,
When the service providing server extracts the first key from the key pool of the service providing server,
A step in which the service providing server applies the key-related information to the first key to generate a key synchronized with the user terminal.
The service providing server includes a step of recovering the received token as confidential information by using the synchronized key.
In the key pool of the user terminal, the second key derived by applying the eigenvalue of the user terminal to the first key is initially stored.
The key-related information includes the eigenvalue of the user terminal and a transmission counter.
The transmission counter is a number that increases by one each time the token is generated and transmitted from the user terminal.
As a stage before or after the stage of generating the token
The stage where the user terminal generates the third key by encrypting the second key using a transmission counter, and
Including a step of updating the key pool of the user terminal by storing the third key in the key pool of the user terminal.
The stage of generating the synchronized key is
The stage of deriving the second key by applying the eigenvalue of the user terminal to the first key, and
An information security method including a step of unidirectionally encrypting the derived second key for the number of times of the transmission counter to generate the synchronized key. The stage of updating the key pool of the user terminal is
The information security method according to claim 4 , wherein the key extracted from the key pool of the user terminal is excluded from the key pool of the user terminal, or the presence or absence of extraction is displayed.