JP2004112571A - Mobile communication device, encryption system, mobile communication method, and encryption method - Google Patents

Abstract

An object of the present invention is to increase availability, flexibility, and feasibility.
A predetermined mobile communication device, a storage server for temporarily storing user data transmitted from the mobile communication device and providing a service related to the user data, the mobile communication device, and the storage server The mobile communication device includes a first key storage unit, a second key storage unit, and a storage request. And a key transmission unit, wherein the output device includes a decryption processing unit, and outputs the decrypted user data in a predetermined output form.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mobile communication device, an encryption system, a mobile communication method, and an encryption method. For example, an MMK terminal decrypts and outputs stored data using a public key transmitted by a mobile phone through local communication. It is suitable for application in cases.
[0002]
[Prior art]
Conventionally, information requiring confidentiality (confidentiality information) such as personal information is transmitted over a network in a state of being encrypted with a predetermined encryption key or stored in a communication device.
[0003]
By encrypting with the encryption key, only the person having the decryption key corresponding to the encryption key can decrypt (or decrypt) the confidentiality information. The information will not be known.
[0004]
[Problems to be solved by the invention]
By the way, the decryption key (for example, an SSL session key (common key)) is usually stored inside a mobile phone or the like equipped with a Web browser, and the mobile phone is not encrypted. When information is received, the information is decrypted with a decryption key.
[0005]
However, for example, when an MMK terminal that is distributed and arranged in a wide area and shared by an unspecified number of users is used for outputting the confidentiality information, the decryption key is provided in the mobile phone, and the encrypted data is stored in the MMK terminal. As described above, a contradiction may occur that the decryption key that defines the decryption operation does not match the information processing device that has the encrypted confidential information that is the target of the decryption operation. .
[0006]
When a mismatch occurs between the information processing apparatuses that store the decryption key and the encrypted confidentiality information, the confidentiality information in the encrypted state is transmitted from the MMK terminal to the mobile phone in order to match them. However, in order to perform this transmission, it is necessary to equip the MMK terminal and the mobile phone with a communication interface for that, and to provide the mobile phone with storage resources sufficient to store the confidentiality information. is there.
[0007]
Even if a communication interface can be prepared, in practice, the storage resources of the mobile phone often do not always have a sufficient capacity. Also, in general, when certain original data is encrypted, the data size after the encryption may be larger than the size of the original data, and it is difficult for the mobile phone to store the confidential information in an encrypted state. However, the feasibility of such a system configuration is reduced.
[0008]
If the mobile phone does not have an output function (for example, a print function) that can appropriately output the confidentiality information according to the user's request and exists only on the MMK terminal side, such a communication interface is used. Even if the confidential information exists and is transmitted to the mobile phone and stored, and the confidential information can be decrypted on the mobile phone side, the decrypted plaintext confidential information cannot be output properly. Problems, low availability and lack of flexibility.
[0009]
Such a problem can also occur when the mobile phone is replaced with a low mobility communication terminal such as a personal computer.
[0010]
[Means for Solving the Problems]
In order to solve this problem, in the mobile communication device of the first invention (for example, the mobile phone 16), a key storage unit (for example, a mobile secret key PV6) for storing a predetermined decryption key (for example, a mobile secret key PV6). Includes a key file F3), a key transmitting unit (for example, a communication unit 30) for reading out and transmitting the decryption key from the key storage unit, and a predetermined decryption device (for example, the MMK terminal 14). By transmitting the decryption key, the encrypted data (for example, the encrypted data ED1) stored in the decryption device is decrypted.
[0011]
Further, in the cryptographic system of the second invention, a predetermined mobile communication device and a storage server for temporarily storing user data transmitted from the mobile communication device and providing a service related to the user data (as an example) Virtual print server 13) and an output device (for example, MMK terminal 14) for outputting the user data in a predetermined output form (for example, printout) in cooperation with the mobile communication device and the storage server. In the encryption system provided, the mobile communication device includes a first key storage unit storing a predetermined encryption key (for example, a mobile public key PB6), and a decryption key (for example, a key) corresponding to the encryption key. A second key storage unit storing the mobile secret key PV6), and a storage unit for encrypting the user data with the encryption key and transmitting the encrypted user data to the storage server for storage. A second unit (for example, the control unit 31) and the encrypted user data (for example, the encrypted data ED1) stored in the storage server are transmitted to the output device. A key transmitting unit that reads the decryption key from the key storage unit and transmits the decrypted key to the output device, wherein the output device uses the decryption key received from the key transmitting unit to encrypt user data. And a decoding processing unit (for example, the control unit 51) for decoding the user data, and outputs the decoded user data (for example, the original data D1) in the output form.
[0012]
Further, in the cryptographic system of the third invention, a predetermined mobile communication device and a storage server for temporarily storing user data transmitted from the mobile communication device and providing a service related to the user data, An output device that outputs the user data in a predetermined output form in cooperation with the mobile communication device and the storage server, wherein the mobile communication device includes a first storage device storing a predetermined encryption key. Key storage unit, a second key storage unit storing a decryption key corresponding to the encryption key, and transmitting the user data to the storage server after encrypting the user data with the encryption key. A storage request unit, and when the encrypted user data stored in the storage server is transmitted to the output device, reads out the decryption key from the second key storage unit, and Characterized in that it comprises a key transmission unit for transmitting the force device.
[0013]
Furthermore, in the mobile communication method of the fourth invention, in the mobile communication method using the mobile communication device provided with the key storage unit and the key transmission unit, a predetermined decryption key is stored in the key storage unit, The key transmission unit reads the decryption key from the key storage unit and transmits the decryption key to a predetermined decryption device. When the decryption device receives the decryption key, the decryption device uses the decryption key to perform the decryption. And decrypting the encrypted data stored in the encryption device.
[0014]
Further, in the encryption method of the fifth invention, a predetermined mobile communication device, a storage server for temporarily storing user data transmitted from the mobile communication device and providing a service related to the user data, In an encryption method related to an output device that outputs the user data in a predetermined output form in cooperation with a mobile communication device and the storage server, the mobile communication device stores a predetermined encryption key in a first key storage unit. In addition, a decryption key corresponding to the encryption key is stored in a second key storage unit, and the storage request unit encrypts the user data with the encryption key and transmits the user data to the storage server. When the encrypted user data stored in the storage server is transmitted to the output device, the key transmitting unit reads the decryption key from the second key storage unit. In the output device, the decryption processing unit decrypts the encrypted user data using the decryption key received from the key transmission unit, and transmits the decrypted user data to the output device. The data is output in the output mode.
[0015]
With such a configuration, the mobile communication device can be used for delivering the decryption key.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(A) Embodiment
Hereinafter, embodiments of a mobile communication device, an encryption system, a mobile communication method, and an encryption method according to the present invention will be described.
[0017]
(A-1) Configuration of the embodiment
FIG. 1 shows an overall configuration example of a communication system 10 according to the present embodiment.
[0018]
In FIG. 1, a communication system 10 includes a network 11, a mobile phone network 12, a virtual print server 13, an MMK terminal 14, a gateway (GW) 15, and a mobile phone 16. Reference numeral 17 denotes a dedicated line provided as needed.
[0019]
The network 11 may be a LAN (local area network) or the like, but is assumed to be the Internet in this case. The mobile phone network 12 is a network operated by a mobile phone operator to accommodate the mobile phone 16. The mobile phone network 12 and the Internet 11 are connected via a gateway 15. All communication when browsing a Web site on the Internet 11 or exchanging e-mail with the Internet 11 from the mobile phone 16 passes through the gateway 15.
[0020]
Since the dedicated line 17 is an alternative to the Internet 11, only the server (the virtual print server 13 in this case) connected to the gateway 15 by the dedicated line 17 is connected to the dedicated line 17 without passing through the Internet 11. It communicates with the mobile phone 16 in the mobile phone network 12 via the mobile phone.
[0021]
Since it is physically impossible for a third party on the Internet 11 to access the dedicated line 17 by using a personal computer or the like, unlike the Internet 11, which has a high risk of data tapping, falsification, and spoofing. On the dedicated line 17, high security can be physically secured.
[0022]
The virtual print server 13 and the MMK terminal 14 provide similar services to a large number of users (one of them U1 who carries the mobile phone 16). The description will proceed with an example in which the service is used.
[0023]
The virtual print server 13 is a server that provides various services necessary for the user U1 to finally print out a desired document from the MMK terminal 14. Although the services that the virtual print server 13 can provide are various, here, the simplest storage service is taken as an example.
[0024]
The storage service provides a storage area (storage) arranged on the Internet 11 to members of the virtual print server 13 (including the user U1). Since this storage area is a part of storage resources mounted on the virtual print server 13 on the Internet 11, it can be accessed from anywhere, for example, from any MMK terminal 14 that is distributed in a wide area. It is also possible to access.
[0025]
FIG. 4 shows an example of the internal configuration of the virtual print server 13.
[0026]
(A-1-1) Example of internal configuration of virtual print server
4, the virtual print server 13 includes a communication unit 40, a control unit 41, and a storage unit 42.
[0027]
The communication unit 40 may basically provide an interface as a Web server (or an FTP server) to the mobile phone 16 and the MMK terminal 14 that have accessed.
[0028]
The control unit 41 corresponds to a CPU (Central Processing Unit) of the virtual print server 13 in terms of hardware, and an OS (Operating System), a DBMS (Database Management System), a Web server, a CGI program ( CGI script (including a CGI script).
[0029]
The storage unit 42 is a storage resource such as a RAM (random access memory) and a hard disk in terms of hardware, and includes a database and various files in terms of software.
[0030]
The storage unit 42 stores files such as a user management file F21 and an encrypted data file F22.
[0031]
The user management file F21 is a file for managing users who have registered as members in the virtual print server 13. Therefore, the minimum amount of personal information to be certified as a member is registered in this user management file F21. For example, information such as a user (member) name, an e-mail address, a user ID, and a password corresponds to this.
[0032]
Since the user U1 is also a member of the virtual print server 13, the personal information is registered in the user management file F21.
[0033]
The encrypted data file F22 stores data (that is, encrypted data ED1) encrypted on the mobile phone 16 by a public key (mobile public key) PB6 described later of the mobile phone 16 and transmitted to the virtual print server 13. This file is generated for temporary storage. The encrypted data file F22 is stored in a storage area provided to the user U1 by the storage service.
[0034]
On the other hand, FIG. 2 shows an example of the internal configuration of a mobile phone 16 that communicates with the virtual print server 13 via the Internet 11 and communicates with the MMK terminal 14 and a communication terminal (not shown) using local communication.
[0035]
(A-1-2) Internal configuration example of mobile phone
2, the mobile phone 16 includes a communication unit 30, a control unit 31, a storage unit 32, an operation unit 33, and a display unit 34.
[0036]
Since the communication unit 30 corresponds to the communication unit 40, the control unit 31 corresponds to the control unit 41, and the storage unit 32 corresponds to the storage unit 42, the detailed description thereof will be omitted.
[0037]
Note that, unlike the control unit 41 on the virtual print server 13 side, this control unit 31 does not include a Web server or a CGI program, but instead includes various programs such as a Web browser mailer.
[0038]
The communication unit 30 has functions for voice communication as a basic telephone, browses a Web page via the Internet 11 (or via a dedicated line 17), performs file transfer, and transmits e-mail. It has a function of transmitting and receiving data, and further has a function of performing local communication with the MMK terminal 14. The local communication of the present embodiment is used to transmit a secret key (mobile secret key) PV6 of the mobile phone 16 from the mobile phone 16 to the MMK terminal 14.
[0039]
The means by which the mobile phone 16 communicates with the MMK terminal 14 may be via the Internet 11 such as e-mail, for example. Local communication in which the MMK terminal 14 and the mobile phone 16 communicate with each other on a one-to-one basis is performed.
[0040]
Local communication is broadly divided into a wired system and a wireless system. In the wired system, the MMK terminal 14 and the mobile phone 16 are directly connected one-to-one with a cable or the like for communication (terminals other than the mobile phone 16 and the MMK terminal 14 are not connected to this cable). The system communicates without using the cable or the like. Some wireless systems use infrared rays and others use radio waves.
[0041]
From the viewpoint of ensuring confidentiality of communication, a wired system is preferable, but from the viewpoint of ease of use, a wireless system that does not require attachment of a connector is superior. Among wireless systems, those that use infrared rays that can communicate only within the range of visibility are less risky to be intercepted and have better confidentiality than those that use radio waves where it is unclear how far they can reach by diffraction. It can be said that there is.
[0042]
If the cable or the infrared ray is utilized in this way, even if the portable secret key PV6 is transmitted in plaintext, the confidentiality can be physically secured during the communication process. Therefore, it is necessary to logically guarantee the confidentiality using the encryption. Although it is low in nature, if necessary, local communication or encryption may be performed. For example, in the case of wireless local communication using the radio waves, there is a risk of being intercepted, so it can be said that encryption is preferable.
[0043]
In order to perform each local communication, two terminals (in this case, the mobile phone 16 and the MMK terminal 14) that communicate with each other are connected to a communication interface corresponding to the local communication (for example, in the case of local communication using infrared rays, , Infrared ports, etc.).
[0044]
When encryption is performed, a public key (MMK public key) PB4 of the MMK terminal 14 can be used as an encryption key. The MMK public key PB4 may be transmitted from the MMK terminal 14 to the mobile phone 16 in plain text by local communication. In a public key cryptosystem described later used in the present embodiment, it is difficult to obtain a corresponding private key from a public key (here, it is difficult to obtain an MMK private key PV4 from an MMK public key PB4). This is because the need to keep the public key PB4 secret is low.
[0045]
Next, the storage unit 32 differs from the storage unit 42 in the files stored.
[0046]
That is, the storage unit 32 stores each file such as the PIM file F1, the key files F2 and F3, the encrypted data file F4, and the original data file F5.
[0047]
Some mobile phones are equipped with PIM (Personal Information Management) software, but when the mobile phone 16 is such a mobile phone, the PIM file F1 may exist.
[0048]
The PIM software is, for example, software for managing personal information such as an address book and a telephone directory, and generates a PIM file F1 for managing a large number of personal information. Whether or not to use such PIM software on the mobile phone 16 is up to the user U1. If the PIM software is not used, the PIM file F1 does not exist, but the user U1 already uses the PIM software, In the case where the PIM file F1 containing a large number of personal information is stored in the storage unit 32, the personal information can be used in this embodiment as necessary.
[0049]
The key files F2 and F3 are files for storing keys used for encryption and decryption.
[0050]
The type of the key differs depending on the encryption method to be used, but in the present embodiment, one of the encryption methods belonging to the public key system is frequently used. This public key cryptosystem is based on security because it is difficult to factor a large number (product n = pq of large prime numbers p and q (each of p and q is 100 digits or more as an example)). Things. This difficulty is caused by the fact that, when a third party attacks data encrypted with the public key or the secret key, for example, the most efficient and least computational factorization algorithm is executed on a computer with the fastest processing speed. Even if it is executed, the difficulty is such that it takes an unrealistically long time (for example, tens of thousands of years) to obtain the solution (that is, to be able to decrypt the encryption). Even if it could be decrypted tens of thousands of years later, it has virtually no meaning to this third party nor to the user U1, so it can be said that the decryption is practically impossible.
[0051]
Note that decryption means that a third party who is not a legitimate recipient attacks the encrypted data using a prime factorization algorithm or the like to obtain plaintext data or a plaintext encryption key. This means that an authorized recipient processes encrypted data using a decryption key (public key or private key) to obtain plaintext data.
[0052]
When encryption and decryption are performed as a protocol below the application layer of the OSI reference model (for example, when the protocol is performed in the transport layer), the communication unit 30 executes the application as an application subject. In such a case, the control unit 31 is the execution subject.
[0053]
In the present embodiment, a pair of mobile public key PB6 and mobile secret key PV6 are generated in advance on the mobile phone 16 using a predetermined key generation program, and for example, the mobile public key PB6 is stored in a key file F2, It is assumed that the secret key PV6 is stored in the key file F3.
[0054]
The original data file F5 is a file for storing original data D1 created and edited by the user U1 on the mobile phone 16, for example. As the original data D1, personal information in the PIM file F1 can be used.
[0055]
The encrypted data file F4 is a file for storing the encrypted data ED1 obtained by encrypting the original data D1 in the original data file F5 with the portable public key PB6.
[0056]
When the encrypted print data ED1 extracted from the encrypted data file F4 is transmitted from the mobile phone 16 to the virtual print server 13, the virtual print server 13 receiving the encrypted data ED1 stores the encrypted data ED1 in the storage unit 42. The encrypted data file F22 is generated on the virtual print server 13 side.
[0057]
Therefore, while temporarily stored in the virtual print server 13, the encrypted data ED1 is always in an encrypted state. In addition, since this encryption is performed using the portable public key PB6, it can be actually decrypted (decrypted) only by using the portable private key PV6 stored in the portable telephone 16.
[0058]
For this reason, the encrypted data file F22 is disclosed on the Internet 11 due to a management error of the system administrator or the like on the virtual print server 13 side, or the encrypted data file F22 is attacked through a security hole of the Web site. Even if the encrypted data file F22 is acquired by a third party, the contents of the original data D1 will not be known to the third party.
[0059]
Further, even a system administrator or a network administrator of the virtual print server 13 can access the encrypted data file F22 with administrator authority (normally, if the administrator has authority, can read and write all files in the virtual print server 13). However, since it can be decoded, the content of the original data D1 cannot be known. This is because the system administrator or the network administrator cannot obtain or generate the mobile secret key PV6. Considering that there are many cases where such legitimate system administrators and network administrators are involved in the leakage in actual personal information leakage cases, the key is concealed from these persons and the original data D1 is concealed. The need to do so is not small.
[0060]
The operation unit 33 is a part operated by the user U1 to transmit an instruction to the mobile phone 16, and for example, a plurality of small mechanical push buttons (keys) are arranged.
[0061]
The display unit 34 is a portion corresponding to a display device that displays a screen according to the function of the Web browser or the like, and allows the user U1 to browse a Web page provided by the Web server of the virtual print server 13.
[0062]
Finally, FIG. 3 shows an example of the internal configuration of the MMK terminal 14. The MMK terminal 14 is an information processing device that is arranged at a high density in a place where many people gather, such as a convenience store or a station, and there are those that have a built-in printer function and those that use an external printer function. In any case, a printer function can be provided to an unspecified number of users (for example, U1).
[0063]
(A-1-3) Example of internal configuration of MMK terminal
3, the MMK terminal 14 includes a communication unit 50, a control unit 51, a storage unit 52, an operation unit 53, a display unit 54, a printing unit 55, and a secret key corresponding unit 56. .
[0064]
Among them, the communication unit 50 corresponds to the communication unit 30, the control unit 51 corresponds to the control unit 31, the storage unit 52 corresponds to the storage unit 32, the operation unit 53 corresponds to the operation unit 33, Since the display unit 54 corresponds to the display unit 34, a detailed description thereof is omitted.
[0065]
The communication unit 50 communicates with the virtual print server 13 via the Internet 11 (or the dedicated line 17) when the document including the personal information is printed out, and also communicates with the mobile phone 16 using the local communication. connect.
[0066]
The storage unit 52 stores files such as an encrypted data file F11 and a secret key file F12 as the processing proceeds.
[0067]
The encrypted data file F11 is a file generated to store the encrypted data ED1.
[0068]
The secret key file F12 is a file generated to store the portable secret key PV6 supplied from the portable telephone 16 by the local communication.
[0069]
In general, it is desirable that the secret key not be transmitted to the outside of the original managed component (in the case of the mobile secret key PV6, the mobile phone 16), but in the present embodiment, the plaintext mobile secret key is used as described later. The PV1 is at least temporarily stored in the secret key file F12 and stored on the MMK terminal 14. This is necessary storage for decrypting the encrypted data ED1 supplied from the virtual print server 13.
[0070]
If the use form of the portable secret key PV1 is a one-time type that becomes invalid only once when it is used for decryption on the MMK terminal 14, it may be left as it is, but it is used repeatedly ( (Or may be used repeatedly), it is necessary to ensure that the MMK terminal 14 cannot be reused.
[0071]
It is the secret key corresponding unit 56 that makes the portable secret key PV6 on the MMK terminal 14 unusable.
[0072]
The secret key corresponding unit 56 makes the portable secret key PV6 in the secret key file F12 unusable by, for example, physically deleting or overwriting.
[0073]
In a general information processing apparatus, there is no logically valid data in the area where the data to be deleted (here, the mobile secret key PV6) is stored even if the deletion operation is simply performed. In many cases, data is physically stored simply by treating it as an area, but in such a case, the data can be read out by a special tool and reused by a third party Sex remains. To cope with this, the secret key corresponding unit 56 physically deletes or overwrites the data (portable secret key PV6) after being used for decryption to make it completely unusable. .
[0074]
As a method for making it unusable, encryption can be used in addition to physical erasure or overwriting. This encryption is for encrypting the portable secret key PV6 on the MMK terminal 14 so that a third party cannot decrypt it. As an example, encryption may be performed using the mobile public key PB6.
[0075]
Note that, in the case of the one-time type, such a process for making the data unusable is unnecessary, but the key generation program on the mobile phone 16 transmits the new encrypted data ED1 to the virtual print server 13. , A new mobile public key (corresponding to PB6) and a mobile secret key (corresponding to PV6) must be generated.
[0076]
Hereinafter, the operation of the present embodiment having the above configuration will be described with reference to the flowchart of FIG.
[0077]
Although the flowchart of FIG. 5 includes the steps of S10 to S21, it can be subdivided into three partial flows.
[0078]
That is, a storage registration flow configured by steps S10 to S14, a registration data acquisition flow configured by S15 to S17, and a print output flow configured by S18 to S21.
[0079]
(A-2) Operation of the embodiment
The user U1 operates the mobile phone 16 to generate original data D1 including highly confidential information such as personal information using the PIM file F1 and the like, and store the generated original data D1 in the original data file F5 (S10). .
[0080]
Next, a pair of the mobile public key PB6 and the mobile secret key PV6 are generated using the key generation program, and the mobile public key PB6 is stored in the key file F2 and the mobile secret key PV6 is stored in the key file F3 (S11).
[0081]
Then, the original data D1 extracted from the original data file F5 is encrypted with the portable public key PB2 extracted from the key file F2, and the encryption result is stored in the encrypted data file F4 as the encrypted data ED1 (S12).
[0082]
Thereafter, when the user U1 accesses the virtual print server 13 using a Web browser or the like of the mobile phone 16, the virtual print server 13 provides a Web page (form) for log-in. Then, the user logs in by inputting a user ID and a password via the server, and transmits the encrypted data ED1 extracted from the encrypted data file F4 to the virtual print server 13 (S13).
[0083]
The communication between the virtual print server 13 and the mobile phone 16 including this transmission uses the dedicated line 17 when the dedicated line 17 is provided, and uses the Internet 11 when the dedicated line 17 is not provided. However, since the gateway 15 determines which one to use, the user U1 does not need to be aware of the existence of the dedicated line 17.
[0084]
On the other hand, the virtual print server 13 receiving the encrypted data ED1 stores and stores the encrypted data ED1 in the encrypted data file F22 (S14). After the storage, the virtual print server 13 enters a standby state waiting for the user U1 to access using an arbitrary MMK terminal 14.
[0085]
This standby state may be continued without limitation until the user U1 accesses, but since a limited storage resource of the storage unit 42 of the virtual print server 13 is consumed, a predetermined state is set. (For example, one week), and if there is no access even after the expiration date, the encrypted data ED1 may be automatically deleted.
[0086]
Note that the order of steps S10 to S13 does not necessarily have to be as shown. For example, it is possible to generate the original data D1 after logging in, or to generate the mobile public key PB6 and the mobile secret key PV6 before generating the original data D1.
[0087]
The step S15 following the step S14 can be started at any time by the user U1 who carries the mobile phone 16 by using a desired MMK terminal 14 from among a large number of MMK terminals distributed in a wide area.
[0088]
That is, when the user U1 accesses the virtual print server 13 using the MMK terminal 14, the virtual print server 13 provides a login Web page (form) or the like as in step S13. The user logs in via the Web page and requests transmission of the encrypted data ED1 (S15). Since the user U1 enters the user ID and the password having the same values as those entered in the login in step S13 in the login in step S15, the virtual print server 13 performs appropriate session management and performs many other operations. The encrypted data ED1 (encrypted data file F22) supplied by the user U1 can be specified from among many encrypted data that can be simultaneously stored in the storage unit 42 in response to a request from the user.
[0089]
When the virtual print server 13 transmits the specified encrypted data ED1 to the MMK terminal 14 (S16), the MMK terminal 14 receives the data via the Internet 11 and stores it in the encrypted data file F11 (S17).
[0090]
The timing for determining whether or not to shift from step S17 to the next step S18 may be left to the operation of the user U1, but the storage resources of the MMK terminal 14 are limited to encrypted data. Since the state has been consumed by the file F11, the MMK terminal 14 and the mobile phone 16 perform local communication and automatically transfer the mobile secret key from the mobile phone 16 to the MMK terminal 14 so that the state can be eliminated as soon as possible. It is good to make it transmit PV6.
[0091]
If it is used repeatedly thereafter, the plaintext mobile secret key PV6 must never be obtained by a third party, and thus high confidentiality is required in this transmission. In the case of using the wired method or the infrared ray as the local communication, the confidentiality is physically secured, and in the case of using the radio wave, encryption is performed.
[0092]
If, for example, the MMK public key PB4 is used in this encryption, it is necessary to transmit the MMK public key PB4 from the MMK terminal 14 to the mobile phone 16 before transmitting the mobile secret key PV6. The transmission of the MMK public key PB4 to the mobile phone 16 can be performed in plain text using local communication.
[0093]
The MMK terminal 14 receives the transmission of the mobile secret key PV6 from the mobile phone 16, and if the mobile secret key PV6 is encrypted with the MMK public key PB4, decrypts it with the MMK secret key PV4 and returns it to plain text. If not, the encrypted data ED1 in the encrypted data file F11 is decrypted using the portable secret key PV6 as it is (S19). By this decoding, the original data D1 is obtained on the MMK terminal 14.
[0094]
Next, the portable secret key PV6 is set in the non-reusable state described above (S20), and the original data D1 returned to the plain text is printed out using the printing unit 55 of the MMK terminal 14 (S21).
[0095]
Here, the order of the step S20 and the step S21 may be reversed. However, in a case where the portable secret key PV6 on the MMK terminal 14 is in a state where the portable secret key PV6 cannot be reused in response to the manual operation of the user U1, the user U1 When the user forgets to perform the manual operation or when the MMK terminal 14 breaks down immediately after printing out, the probability that the plaintext portable secret key PV6 remains as it is on the MMK terminal 14 is increased. , The order shown is preferred. In the order shown in the figure, the portable secret key PV2 cannot be printed out unless the portable secret key PV2 is in a non-reusable state.
[0096]
Thus, for example, the probability that the maintenance worker of the MMK terminal 14 obtains the plaintext portable secret key PV6 can be reduced.
[0097]
As described above, in the present embodiment, when there is no communication interface for transmitting the encrypted data ED1 from the MMK terminal 14 to the mobile phone 16, or when the mobile phone 16 does not have a printing function (generally, the mobile phone 16 does not have a printing function). Even if the telephone does not have a print function), the original data D1 can be printed out from the MMK terminal 14, and the user U1 can obtain a print result at a desired place.
[0098]
The mobile phone 16 of the present embodiment functions as a delivery means of a key (mobile secret key PV6) for decrypting the encrypted data ED1 stored in the MMK terminal 14 on the MMK terminal 14, and is viewed from the user U1. In this case, the behavior of carrying the mobile phone 16 is equivalent to the key delivery, so that it looks as if the mobile phone 16 is substantially a key.
[0099]
(A-3) Effects of the embodiment
As described above, according to the present embodiment, it is possible to flexibly respond to the request of the user (for example, U1), and to provide a highly available system.
[0100]
Also, in the present embodiment, the mobile phone (16) having only a small storage capacity does not need to store the original data (D1) and its encrypted data (ED1), which may have a large data size. It can be said that the feasibility is high.
[0101]
(B) Other embodiments
Regardless of the above embodiment, a server (storage server) that provides a storage service is prepared separately from the virtual print server 13, and the storage service is provided in cooperation with the virtual print server 13 and the storage server. It doesn't matter. Further, the storage of the encrypted data in the virtual print server 13 (or the storage server) is not necessarily limited to temporary storage, but may be permanent.
[0102]
The above-described key generation program may be supplied from the virtual print server 13 to the mobile phone 16 via the mobile phone network 12 via the Internet 11 or the dedicated line 17.
[0103]
In the above embodiment, the confidentiality of the original data D1 is ensured by the portable secret key PV6, but it is desirable to detect spoofing and falsification as necessary. This is because not only data eavesdropping but also spoofing and falsification can be performed on the Internet 11. Even if encryption using the mobile public key PB6 is sufficient to ensure data confidentiality, the method of detecting spoofing and falsification is based on the transmission of the encrypted data ED1 from the mobile phone 16 to the virtual print server 13, and It is necessary to execute the transmission of the encrypted data ED1 from the virtual print server 13 to the MMK terminal 14 for each section.
[0104]
As a method of detecting spoofing, for example, the following method can be used.
[0105]
That is, when the encrypted data ED1 is transmitted from the mobile phone 16 to the virtual print server 13, the encrypted data ED1 is further encrypted on the mobile phone 16 with the mobile secret key PV6 and received. The virtual print server 13 decrypts with the portable public key PB6 (however, the result of the decryption is not plain text (original data D1), but is still encrypted with the portable public key PB6 (that is, the encrypted data ED1 is not used). )). Then, when transmitting the encrypted data ED1 from the virtual print server 13 to the MMK terminal 14, the encrypted data ED1 is further encrypted on the virtual print server 13 with the secret key (server secret key) of the virtual print server 13 and received. Then, the MMK terminal 14 may perform decryption using the public key (server public key) of the virtual print server 13 (the result of the decryption is the encrypted data ED1).
[0106]
After this decryption, if the result of decryption with the portable secret key PV6 is a normal plaintext, it is found that the relay route of the plaintext data (D1) is normal, and there is no spoofing. You can confirm that. That is, it is possible to confirm that the data D1 is transmitted by the user U1 from the mobile phone 16 and reaches the MMK terminal 14 via the virtual print server 13.
[0107]
The mobile public key PB6 used for decryption on the virtual print server 13 and the server public key used for decryption on the MMK terminal 14 are distributed to the virtual print server 13 and the MMK terminal 14 in advance. Good to put.
[0108]
On the other hand, as a method of detecting the alteration, for example, the following method can be used.
[0109]
That is, the hash value (digest), which is the result of calculating the plaintext original data D1 with a predetermined hash function, is passed on the relay route with the hash value (digest) added to the encrypted data ED1, and the final MMK terminal 14 When a decryption result (if there is no falsification, the decryption result is equal to the original data D1) is obtained, a hash value of the decryption result is obtained using a hash function stored in the MMK terminal 14 in advance. If the hash value obtained in step (1) and the hash value added to and transmitted to the encrypted data ED1 match, it is determined that there is no tampering, and if they do not match, it is determined that there is tampering. It goes without saying that the hash value added to the encrypted data ED1 may be added after being encrypted.
[0110]
However, as in the above embodiment, when the source of the original data D1 and the user who receives the printout result are the same user U1, if the original data D1 is a simple document (for example, a document having a small number of characters), the user U1 itself However, since the presence or absence of tampering can be easily confirmed visually, the necessity of detecting tampering is small.
[0111]
In the case where the original data D1 is a document for which it is not easy to visually confirm whether there is falsification, or when a user (other than U1) different from the transmission source of the original data D1 receives the printout result (in this case, lending the mobile phone 16) , Or sharing of the mobile secret key PV6 between a plurality of users is required), it is desirable that the presence or absence of tampering can be confirmed using the hash value or the like.
[0112]
In the case where the dedicated line 17 is used, as long as the transmission path between the mobile phone 16 and the virtual print server 13 is concerned, there is no risk of eavesdropping, spoofing, and tampering, and the encryption is performed as described above. The process of further encrypting the data ED1 with the portable secret key PV6 and decrypting the data ED1 with the portable public key PB6 in the virtual print server 13 which has received the data ED1 can be omitted.
[0113]
In view of the low processing capability of a mobile phone as an information processing device and the lack of an environment in which an arbitrary program can be executed, a mobile phone other than the mobile phone 16 accommodated in the mobile phone network 12 can eavesdrop or spoof. This is because there is almost no possibility of tampering.
[0114]
The form of output of the original data D1 from the MMK terminal 14 is not limited to the above-described print output. For example, a screen display output may be used. Since MMK terminals usually have a display screen that is much larger than mobile phones, it is possible to display detailed images, which are difficult to see with mobile phones, in more detail and more faithfully. It is.
[0115]
Note that the mobile phone (16) used in the above embodiment can be replaced with another mobile communication terminal. For example, it can be replaced with a PDA or a PHS terminal.
[0116]
Further, the mobile phone (16) can be replaced with a communication terminal that has mobility but does not have portability.
[0117]
In the above embodiment, the original data D1 is encrypted on the mobile phone 16, but this encryption may be performed by components other than the mobile phone 16.
[0118]
For example, when the dedicated line 17 is provided, the plaintext original data D1 is transmitted from the mobile phone 16 to the virtual print server 13 via the dedicated line 17, and encryption is performed on the virtual print server 13. You may. The decryption key (private key) corresponding to the encryption key (for example, public key) used for the encryption may be delivered to the mobile phone 16 via the dedicated line 17 in plain text, for example.
[0119]
When the Internet 11 is used instead of the dedicated line 17, the original data D1 is encrypted on the mobile phone 16 using the server public key, and the encrypted data is transmitted to the virtual print server 13 via the Internet 11 to perform virtual printing. The server 13 decrypts the original data D1 using the server secret key, encrypts the original data D1 using a predetermined encryption key, and encrypts the decryption key corresponding to the encryption key with the server secret key. Then, when the data is transmitted to the mobile phone 16 via the Internet 11 and received, the mobile phone 16 can decrypt the data using the server public key to obtain the decryption key in plain text.
[0120]
The processing after the mobile phone 16 obtains the plaintext decryption key may be the same as in the above embodiment.
[0121]
The MMK terminal (14) used in the above embodiment can be replaced with another type of communication terminal.
[0122]
Further, the public key cryptosystem can be replaced with another cryptosystem. For example, a common key cryptosystem can be used.
[0123]
In the above description, the present invention is implemented mainly by software, but the present invention can also be implemented by hardware.
[0124]
【The invention's effect】
As described above, according to the present invention, availability, flexibility, and feasibility are high.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an overall configuration example of a communication system according to an embodiment.
FIG. 2 is a schematic diagram illustrating an example of an internal configuration of a mobile phone used in the embodiment.
FIG. 3 is a schematic diagram showing an example of an internal configuration of an MMK terminal used in the embodiment.
FIG. 4 is a schematic diagram illustrating an example of an internal configuration of a virtual print server used in the embodiment.
FIG. 5 is a flowchart illustrating an operation example of the embodiment.
[Explanation of symbols]
10 communication system, 11 network, 12 mobile phone network, 13 virtual print server, 14 MMK terminal, 15 gateway, 16 mobile phone, 30, 40, 50 communication unit, 31, 41, 51 Control unit, 32, 42, 52 storage unit, 55 printing unit, 56 private key corresponding unit, PB4 MMK public key, PV4 MMK private key, PB6 mobile public key, PV6 mobile private key.

Claims (9)

A key storage unit storing a predetermined decryption key,
A key transmission unit that reads the decryption key from the key storage unit and transmits the decryption key,
A mobile communication device for transmitting encrypted data to a predetermined decryption device to decrypt data in an encrypted state stored in the decryption device. The mobile communication device according to claim 1,
A mobile communication device, wherein a secret key in a public key cryptosystem is used as the decryption key, and after decryption, the secret key on the decryption device is made unreusable. A predetermined mobile communication device, a storage server that temporarily stores user data transmitted from the mobile communication device and provides a service related to the user data, and cooperates with the mobile communication device and the storage server. An output device for outputting the user data in a predetermined output form,
The mobile communication device,
A first key storage unit storing a predetermined encryption key,
A second key storage unit storing a decryption key corresponding to the encryption key,
A storage request unit for encrypting the user data with the encryption key and transmitting the user data to the storage server for storage;
A key transmitting unit that reads out the decryption key from the second key storage unit and transmits the decrypted key to the output device when the encrypted user data stored in the storage server is transmitted to the output device; With
The output device,
Using the decryption key received from the key transmission unit, a decryption processing unit that decrypts the encrypted user data, and outputs the decrypted user data in the output form Cryptographic system. The encryption system according to claim 3,
As the encryption key, a public key in a public key cryptosystem is used, and as the decryption key, a secret key corresponding to the public key is used. After decryption, the secret key on the output device is used. A non-reusable state. A predetermined mobile communication device and a storage server for temporarily storing user data transmitted from the mobile communication device and providing a service related to the user data are linked with the mobile communication device and the storage server. And an output device that outputs the user data in a predetermined output form.
The mobile communication device,
A first key storage unit storing a predetermined encryption key,
A second key storage unit storing a decryption key corresponding to the encryption key,
A storage request unit for encrypting the user data with the encryption key and transmitting the user data to the storage server for storage;
A key transmitting unit that reads out the decryption key from the second key storage unit and transmits the decrypted key to the output device when the encrypted user data stored in the storage server is transmitted to the output device; And a cryptographic system comprising: In a mobile communication method using a mobile communication device including a key storage unit and a key transmission unit,
A predetermined decryption key is stored in the key storage unit,
The key transmission unit reads the decryption key from the key storage unit and transmits the decryption key to a predetermined decryption device;
The mobile communication method, characterized in that the decryption device, upon receiving the decryption key, uses the decryption key to decrypt data in an encrypted state stored in the decryption device. . The mobile communication method according to claim 6,
A mobile communication method, wherein a secret key in a public key cryptosystem is used as the decryption key, and after decryption, the secret key on the decryption device is made unreusable. A predetermined mobile communication device, a storage server that temporarily stores user data transmitted from the mobile communication device and provides a service related to the user data, and cooperates with the mobile communication device and the storage server. A cryptographic method for an output device that outputs the user data in a predetermined output form,
In the mobile communication device,
A predetermined encryption key is stored in a first key storage unit, and a decryption key corresponding to the encryption key is stored in a second key storage unit.
A storage request unit, which encrypts the user data with the encryption key and transmits the user data to the storage server for storage;
When the encrypted user data stored in the storage server is transmitted to the output device, the key transmission unit reads the decryption key from the second key storage unit and sends the decryption key to the output device. Send,
In the output device,
Using the decryption key received from the key transmission unit, a decryption processing unit decrypts the encrypted user data, and outputs the decrypted user data in the output form. Encryption method. The encryption method according to claim 8,
As the encryption key, a public key in a public key cryptosystem is used, and as the decryption key, a secret key corresponding to the public key is used. After decryption, the secret key on the output device is used. An encryption method characterized by making a non-reusable state.

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