JP2011216034A - Electronic file management system and management method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic file management system and method for securely and reliably managing encrypted files while reducing a burden on a client, systematically managing the encrypted files, and seamlessly adding and coupling encrypted files without modifying a standard web browser.SOLUTION: A file of a client 100 is encrypted and is transmitted to a web file server 200. The file remains encrypted even after the encrypted file is stored in the web file server. An encryption key for file encryption is automatically generated and managed for each session between the client and the server. The client is configured by adding an encrypting filter processing part 120 and a redirect driver 130 in addition to existing standard web browser functions.

Description

  The present invention encrypts an electronic file owned by a client and saves it on a Web server, and allows only the third party to whom the client grants the access right to manage and use the electronic file by the client itself and to use the electronic file. The present invention relates to an electronic file management system and a management method.

  As an application that enables a client to manage files and folders on a Web server, there is WebDAV (Web-based Distributed Authoring and Versioning).

  This WebDAV is a protocol defined for the purpose of editing (Authoring) and revision management (Versioning) of Web contents, and uses HTTP (Hypertext Transfer Protocol) for transmitting a file published by a Web server to a Web browser. It is possible to expand and send documents created on the client to the server for publication, obtain a list of files and folders on the server, and copy, move, and delete files and folders.

  For access to these files and folders, user authentication is usually performed using a user name and password, and only authorized users can use WebDAV. In addition, although it can be said that functions such as file transfer are close to FTP (File Transfer Protocol), encryption using SSL (Secure Socket Layer) protocol, proxy, and the like can be used as they are.

  However, WebDAV does not have a function for storing encrypted files. That is, the file itself is not secure when it is stored on the disk in the server. For this reason, there is a risk of leakage, falsification, extraction, etc. when directly accessed on the server side, not via the network.

  As a method for encrypting a file, there are a common key encryption method, a public key encryption method, a combination method of both methods, and a hash function (one-way encryption) method. Various file management systems have been proposed in which files are encrypted and stored in a Web server using these encryption methods to increase file security. For example, in Patent Document 1, when a file server stores a file encrypted with the client's private key and receives an access request to the encrypted file from the client, the file server retrieves the corresponding file based on the file identification information. Search and send to client. Here, a cryptographic management server connected to the client over the network is provided, and this cryptographic management server identifies the client's private key encrypted with the public key of the cryptographic management server and the encrypted file stored in the file server from the client. Information and client identification information, and the client private key is decrypted with the private key of the encryption management server, and the decrypted client private key is encrypted with the client public key to obtain the client identification information and the file identification information. Store in association with.

JP 2005-209181 A

  (1) The conventional file management system has a problem in realizing safe and reliable management of encrypted files.

  For example, tools for managing files are limited to private use. That is, the owner of the file manages the private key or spell phrase for encryption privately on the client, and uses the encryption key or spell phrase for the client for encryption and decryption. Can only be encrypted and decrypted. For this reason, there is no key or spell phrase notification means for permitting third parties access to files stored and managed by the client, and electronic files cannot be used by third parties.

  In addition, there is a system that digitizes the patient's medical record, but in order for other hospitals and doctors to view the patient's electronic medical record and use it for medical care, the patient's personal information is safely and reliably managed. It becomes a problem. Similarly, it becomes a problem when applied to management of employee information files and customer information files.

  In addition, to prevent leakage of encryption keys and spell phrases for file encryption, the client itself stores them, and it becomes a burdensome information management, and management costs (time, expense, hardware, know-how) Also grows.

  (2) A conventional file management system does not have a mechanism for encrypting an electronic file to be shared by an individual or an organization and systematically managing the encrypted file.

  For example, if what was managed in paper, such as asset information, has moved to computerization in the future, there are no mechanisms such as financial significance and ownership location management, asset owner legitimacy management. Moreover, there is no mechanism for inheriting and inheriting an electronically owned file of the owner as an asset other than personal management.

  The object of the present invention is to securely and reliably manage encrypted files with less burden on the client, systematically manage encrypted files, and seamlessly add and modify standard web browsers without modification. To provide an electronic file management system and management method that can be combined.

  In order to solve the above problems, the present invention encrypts a file owned by a client, transmits it to a Web file server, and further encrypts the file itself even when stored in the Web file server. Only the successor authorized by the file owner can decrypt.

  In addition, the encryption key for file encryption is automatically generated and managed for each session between the client and the server, thereby making it unnecessary to remember the encryption key and the spelling phrase.

  In addition to the existing standard Web browser function, the client also provides an encryption filter processing unit and a redirect driver, encrypts the files to be managed, stores them in the Web file server database, and stores the electronic file by the client. By enabling only third parties who have access rights to manage / use and decryption and use of encrypted electronic files, it is possible to seamlessly add / join standard web browsers without modification. To do.

  Therefore, the present invention is characterized by the following electronic file management system and management method.

(Invention of the system)
(1) The electronic file owned by the client is encrypted and stored in the Web file server, and the electronic file can be managed and used by the client itself, and only the third party to whom the client permits the access right can use the electronic file. An electronic file management system,
The client performs an authentication service by communication of an encrypted file with a Web browser that performs TCP / IP communication of a plain text file with the Web file server or another client, and communication with the authentication server. , File analysis, file encryption key generation, file encryption / decryption, public key / private key linkage management, and switching between the Web browser or encryption filter processing unit and the Web file server And a redirect driver that enables TCP / IP communication with the authentication server,
The Web file server includes an SQL server that executes management of writing / reading of an encrypted file to / from a database, and a Web server that enables HTTP communication of a plain text file with the client using TCP / IP. It is characterized by.

  (2) The client and the Web file server include an SSL protocol for encrypting and transmitting / receiving a file for TCP / IP communication on a network.

  (3) The cryptographic filter processing unit performs hybrid authentication of a valid owner / legal successor of the encrypted file by using a public key authentication infrastructure and a fingerprint authentication token held in the individual authentication device. It is characterized by having means to enable startup with success.

(4) When a legitimate owner with individual authentication uses it personally without transferring it to others,
The encryption filter processing unit manages the file encryption key as an encryption pack (P key pack n) with the public key of the valid owner and transmits it to the Web server when the individual authentication of the valid owner succeeds. Means to
The Web server includes means for displaying content by managing the encrypted file and the P key pack n.

(5) When transferring an encrypted file held by a legitimate owner with individual authentication to another client,
The encryption filter processing unit, when succeeding in individual authentication of a valid owner, designates a “legitimate successor” to be transferred by a valid owner of an encrypted file with a certificate authority of the authentication server. The file encryption key is managed as an encryption pack (I key pack m) with the secret key / public key management mechanism executed in cooperation and the public key of the “legitimate successor” obtained from the certificate authority, and to the Web server Means for transmitting,
The Web server includes means for displaying content by managing an encrypted file and the I key pack m.

(Invention of method)
(6) A system configuration that enables network communication between the client, the Web file server, and the authentication server, encrypts an electronic file owned by the client, stores it in the Web file server, and manages the electronic file by the client itself An electronic file management method that allows only a third party whose access rights have been granted by the client and the client to use the electronic file,
The encryption filter processing unit provided in the client encrypts the file Xn owned by the client itself and stores it in the database of the Web file server as a processing procedure (S1) with a common key kn created for each file registration process A step of encrypting Xn, (S2) a step of creating key possession information Ea obtained by encrypting a common key kn with a public key A acquired from an authentication server, and (S3) a file with a private key a previously owned A step of creating a signature Xn of Xn, (S4) a step of creating a cryptographic context C (kn, μ (Xn), S (Xn, a)), and (S5) of the key possession information Ea and the cryptographic context C Rewriting the HTTP packet and sending it to the web file server,
The Web file server includes (S6) creating file management information, and (S7) sending a response message indicating completion of the encrypted file storage process to the client.

(7) The encryption filter processing unit acquires the encrypted file stored by the client itself as a procedure for acquiring the encrypted file.
(S11) The client transmits a data acquisition request for the file Xn with the acquisition permission from the Web browser to the Web file server via the Internet, and the key ownership information Ea and the encryption are transmitted from the Web file server 200 as the data of the requested file. Capturing in the cryptographic filter processing unit in a set of contexts C;
(S12) obtaining encrypted data from the encryption context;
(S13) decrypting the common key kn with a secret key a previously owned;
(S14) decrypting the file Xn with the common key kn;
(S15) verifying the validity of the file Xn decrypted with the public key A and the signature Xn acquired from the authentication server;
(S16) including the step of transferring the decrypted file Xn to the Web browser after correcting the HTTP packet and displaying it.

(8) As an encryption key acquisition processing procedure for transferring a file from the client A to the client B,
When receiving the file transfer request to the client B (S17), the encryption filter processing unit of the client A transmits the designated data of the file owned by the client A to the client B to the management area of the Web file server via the Internet. And having a step to
The Web file server (S18) designating an encryption data area to be managed as file management information of the client A designated in the management area; and (S19) key ownership of the designated file in the encryption data area. A step of passing the key ownership information Ea to the management area of the information Ea and the encryption context C; (S20) in the management area, the key ownership information Ea encrypted with the public key A of the client A is obtained, and this key ownership Transmitting the information Ea to the encryption filter processing unit of the client A via the Internet,
The encryption filter processing unit that has received the key possession information Ea (S21) uses the secret key a to decrypt the common key kn, and (S22) uses the public key B of the client B acquired from the authentication server. The method includes a step of creating key transfer information Eb obtained by encrypting the common key kn.

(9) As an encryption key transfer processing procedure for transferring a file from the client A to the client B,
The encryption filter processing unit of the client A that has acquired the key transfer information Eb encrypted with the public key B (S23) specifies the client B to be transferred and sends the key transfer information Eb to the Web file server via the Internet. A step of transmitting to the management area,
(S24) Key ownership information Ea managed in the encryption data area as file management information of the client A in the management area, and key transfer information encrypted with the public key B in the encryption context C area A step of adding Eb; (S25) file management information to which the key transfer information Eb has been added is created as file management information MB of the client B and stored in the management area 220A; (S26) a response message And transmitting to the encryption filter processing unit of the client A via the Internet.

(10) As a procedure for generating the common key (file encryption key),
The authentication service processing unit of the client A logged on with the account information (S27) owns the secret key a and the public key A in advance, acquires the public key W from the authentication server, and creates an arbitrary challenge code XA. (S28) creating an identifier A of the client A from the challenge code XA; (S29) creating a client challenge 1 in which the challenge code XA is encrypted with the public key W; and (S30) the client. Recording the identifier A of A in the session management information and transmitting it to the authentication server via the Internet,
The authentication unit of the authentication server (S31) decrypts the client challenge 1 with the secret key W and extracts the challenge code XA; and (S32) an identifier from the challenge code XA and the challenge code XW created at random Creating W, and recording the identifier W in session management information,
(S33) creating a server challenge 2 by encrypting the challenge code XW with a public key A (S33); (S34) processing the authentication service process with the server challenge 2, the identifier A, and the identifier W via the Internet Sending to the department,
The authentication service processing unit (S35) decrypts the server challenge 2 with a secret key a, and (S36) creates an identifier W from the challenge code XA and the challenge code XW, and the identifier W received by the identifier W And (S37) registering the confirmed identifier W in session management information, and (S38) creating a common key k from the challenge code XA and the challenge code XW. ,
(S41) creating a common key k from the challenge code XA and challenge code XW; and (S42) transmitting a logon response (with an identifier) to the authentication service processing unit via the Internet. Have
The authentication service processing unit has a step (S43) of transferring to the Web browser as a logon response,
After the generation of the common key (file encryption key), authentication by the authentication service processing unit and the authentication server is transmitted with (S44) identifier information and nonce (plaintext and common key encryption) added, and the receiving side uses the identifier. Are registered in the session management information, and the step of confirming that the plaintext nonce coincides with the decryption of the encrypted nonce.

  As described above, according to the present invention, it is possible to manage the encrypted file safely and reliably with less burden on the client, systematically manage the encrypted file, and further, without modifying the standard Web browser. Can be added and combined seamlessly.

  Specifically, the file owned by the client and the file owner were permitted by encrypting the file owned by the client, sending it to the web file server, and further encrypting the file itself even when stored in the web file server. Only the successor can decrypt.

  In addition, the encryption key for file encryption is automatically generated and managed for each session between the client and the server, thereby making it unnecessary to remember the encryption key and the spelling phrase.

  In addition to the existing standard Web browser function, the client also provides an encryption filter processing unit and a redirect driver, encrypts the files to be managed, stores them in the Web file server database, and stores the electronic file by the client. By enabling only a third party who has permitted access rights to the management / use and the client to decrypt and use the encrypted electronic file, the standard web browser can be added and combined seamlessly without modification.

The block diagram of the electronic file management system which shows embodiment of this invention. The network block diagram of an electronic file management system. File management image by electronic file management system. Detailed view of client processing functions. Detailed view of processing function of Web file server. Explanatory drawing of the basic element used for file management. FIG. 6 is a diagram illustrating a normal file storage processing procedure performed by the client A. FIG. 6 is a flowchart of storage processing procedures for an encrypted file by a client A. FIG. 11 is a flowchart of an acquisition process procedure for an encrypted file stored by the client A itself. The encryption key acquisition process sequence diagram for file transfer to the client B. The encryption key transfer processing procedure figure for file transfer to the client B. FIG. Common key (file encryption key) generation procedure diagram (part 1). Generation procedure diagram of a common key (file encryption key) (part 2). Generation procedure diagram of a common key (file encryption key) (No. 3).

(1) System Configuration and Encrypted File Management FIG. 1 is a configuration diagram of an electronic file management system showing an embodiment of the present invention. In the figure, the electronic file management system stores the encrypted file on the Web file server side and uses the file by an authorized third party through network communication between the client 100 and the Web file server 200 and the authentication server 300. enable. Each unit is composed of a computer resource and software that realizes a desired processing function using the computer resource.

  FIG. 2 shows a network configuration of the electronic file management system. Three clients 100A, 100B, and 100C can be connected to the Internet, and these can communicate between the Web file server 200 and the authentication server 300. Is done.

  The client 100 enables HTTP communication of a plain text file by TCP / IP with another server such as the Web file server 200 by the standard Web browser 110 or another client. In addition to this standard Web browser function, the client 100 is provided with an encryption filter processing unit 120 and a redirect driver 130, encrypts a file to be managed, stores it in the database 210 of the Web file server 200, and performs electronic processing by the client. Manage and use files and allow only third parties authorized by the client to decrypt and use encrypted electronic files.

  This example is shown in FIG. 3, and the client 100A as the file owner encrypts the plaintext data file FA and stores it in the database 210 via the SQL server 220, and only the client 100B with the encrypted file XA as the successor. The client 100B can obtain the original file FA by assigning it to (decrypting is permitted) and decrypting it. Since the access right is not permitted from the client 100A, the client 100C cannot decrypt or use the encrypted electronic file.

  FIG. 4 shows details of the processing functions of the client. The redirect driver 130 switches (redirects) the input source of the file or communication stream to the Web browser 110 or the encryption filter processing unit 120 to enable TCP / IP communication to the Web file server 200, the authentication server 300, and the like. Conversely, a file or communication stream from the Web file server 200 or the authentication server 300 is switched (redirected) to the Web browser 110 or the encryption filter processing unit 120 to enable TCP / IP communication. Such switching (redirection) is performed via a socket 140 by an IP address and a port number in TCP / IP communication. In addition, a file for TCP / IP communication on the network can be encrypted by the SSL protocol 150 and transmitted / received.

  The encryption filter processing unit 120 performs file analysis, file encryption key generation, file encryption / decryption, public key / private key communication in the authentication service by communication of the encrypted file with the Web file server 200 and communication with the authentication server 300. Implement linked management. Further, the cryptographic filter processing unit 120 performs hybrid authentication of the legitimate owner / legitimate successor by using the public key authentication infrastructure and the fingerprint authentication token held in the individual authentication device 160, and the individual authentication succeeds. Start up is possible.

  As shown in FIG. 5, the Web file server 200 manages the writing / reading of data (encrypted file in this embodiment) with respect to the database 210 in the same manner as a general Web file server. Database management system) 220, and the Web server 230 enables HTTP communication by TCP / IP for plain text files with clients. Further, switching between the database 210 by the Web server 230 and the SQL server 220 is performed via a socket 240 based on an IP address and a port number in TCP / IP communication. In addition, a file for TCP / IP communication on the network can be encrypted by the SSL protocol 250 and transmitted / received.

  In addition, the file management using the encryption key by the encryption filter processing unit 120 performs the following processing by a legitimate owner who is individually authenticated by a fingerprint authentication token or the like.

(A) When the rightful owner uses it personally without transferring it to others When the individual authentication succeeds, the rightful possession is made using the public key and secret key implemented in the token (hidden area) in advance. The file encryption key is managed as an encryption pack (hereinafter referred to as P key pack n) with the user's own public key. This P key pack n is a private key pack No. This means n, and the numbering, file name, etc. are appropriately set. These encrypted files and “P key pack n” are simultaneously transmitted to the Web server. On the Web server side, as shown in FIG. 5, the encrypted file 210A and the “P key pack n” 210B are managed by an SQL server or the like, and the contents are displayed.

(B) When transferring to a legitimate successor The legitimate owner of the encrypted file designates the “legitimate successor” to be transferred. This designation is set, for example, in the user interface (assignment designation) of the cryptographic filter processing unit 120. This designation is executed by the secret key / public key management mechanism of the encryption filter processing unit 120 in cooperation with the certificate authority of the authentication server 300. The “legitimate owner” encrypts the file encryption key with the public key of the “legitimate successor” obtained from the certificate authority (hereinafter referred to as I key pack m). This I key pack m is an inheritance key pack no. This means m, and the numbering, file name, etc. are set as appropriate. The encrypted file and “I key pack m” are simultaneously transmitted to the Web server. On the Web server side, as shown in FIG. 5, the encrypted file 210A and the “I key pack m” 210C are managed by an SQL server or the like, and the content is displayed.

  With this mechanism, the concealed file encryption key is transferred to the “legitimate successor. If the“ legitimate owner ”attaches a signature with his / her private key, the“ legitimate successor ” By verifying the signature with the public key of the “legitimate owner”, transfer from the “legitimate owner” can be confirmed.

(2) Encrypted File Management Procedure This procedure will be described with reference to FIGS. First, FIG. 6 shows basic elements used for file management of the electronic file management system, which are represented by the public key A and the secret key a of the client A, and the clients B and C are similarly represented. , C, the common key kn and the file Xn are written as they are. In addition, information obtained by compressing / encrypting the file Xn is expressed by an encryption context C (kn, μ (Xn), S (Xn, a)), and each part symbol is decrypted by the common key kn and disclosed to the client A. This means that the signature is verified with the key A. Key possession (or key transfer) information is expressed as E (A, kn), and the common key kn is encrypted with the public key A, meaning that it can be decrypted with the private key a. . File management information (for client A) is expressed as info (Xn, A), and stored in a file name, key ownership (or key transfer) information, and data storage area location (link (Xn)).

  FIG. 7 shows a normal file storage processing procedure by the client A, a data transmission request is sent from the Web browser 110 to the encryption filter processing unit 120, an HTTP data stream is analyzed by the encryption filter processing unit 120, and the Web is transmitted via the Internet. Data is transmitted to the file server 200 side, and a response message indicating that the data has been received is received from the Web server side (processing is continued and data is transmitted).

  FIG. 8 shows the procedure for storing the encrypted file by the client A. The transmission request of the file Xn is sent from the Web browser 110 to the encryption filter processing unit 120, and the encryption filter processing unit 120 encrypts the file Xn with the common key kn created for each file registration process (S1), and (S2) authentication. Key ownership information Ea obtained by encrypting the common key kn with the public key A acquired from the server, (S3) A signature Xn of the file Xn is created with the private key a previously owned, and (S4) the encryption context C (kn, μ (Xn), S (Xn, a)) is created, and (S5) the key possession information Ea and the HTTP packet of the encryption context C are rewritten and transmitted to the Web file server 200.

  In the Web file server 200, (S6) file management information to be described later is created, and (S7) a response message is transmitted to the client and received by the client A to confirm that the encrypted file storage processing has been completed. To do.

  FIG. 9 shows an acquisition process procedure of the encrypted file stored by the client A itself. (S11-1) The client A transmits a data acquisition request for the file Xn with the acquisition permission from the Web browser 110 to the Web file server 200 via the Internet, and (S11-2) the Web file server as the data of the requested file. 200, the key ownership information Ea and the encryption context C as a set are fetched into the encryption filter processing unit 120, (S12) the encryption data is obtained from the encryption context, and (S13) the common key kn is decrypted with the private key a previously owned. (S14) The file Xn is decrypted with the common key kn, (S15) the validity of the file Xn decrypted with the public key A and the signature Xn acquired from the authentication server 300 is verified, and (S16) the decrypted file Xn Is transferred to the Web browser 110 through the modification of the HTTP packet, and the Web browser 1 To display at 0.

  FIG. 10 shows an encryption key acquisition (get) processing procedure for transferring a file from the client A to the client B. The encryption filter processing unit 120 of the client A (S17-1) receives the file transfer request from the Web browser 110 to the client B. (S17-2) The file owned by the client A to be transferred to the client B (Web file server) Specified data) is transmitted to the management area (for example, the management area of the SQL server 220) 220A of the Web file server 200 via the Internet.

  The Web file server 200 designates an encrypted data area (for example, an encrypted data area of the SQL server 220) 220B managed by the file management information MA of the designated client A in (S18) management area 220A, and (S19) encrypted data. Of the key ownership information Ea and encryption context C of the specified file in the area 220B, the key ownership information Ea is passed to the management area 220A. (S20) In the management area 220A, the key ownership information encrypted with the public key A of the client A Ea is obtained, and this key ownership information Ea is transmitted to the encryption filter processing unit 120 of the client A via the Internet.

  The encryption filter processing unit 120 that has received the key ownership information Ea (S21) decrypts the common key kn with the secret key a, and (S22) uses the public key B of the client B acquired from the authentication server 300 to obtain the common key kn. Encrypt.

  FIG. 11 shows an encryption key transfer process procedure for transferring a file from the client A to the client B. The encryption filter processing unit 120 of the client A that has acquired the key transfer information Eb encrypted with the public key B by the process of FIG. 10 (S23) specifies the client B to be transferred and transmits the key transfer information Eb via the Internet. To the management area 220A of the Web file server 200.

  The Web server 220 (S24) uses the key ownership information Ea managed in the encryption data area 220B as the file management information MA of the client A in the management area 220A and the key transfer information encrypted with the public key B in the encryption context area C. Add Eb. (S25) The file management information to which the key transfer information Eb is added is created as the file management information MB of the client B and stored in the management area 220A. (S26) This is sent as a response message to the client A via the Internet. Is transmitted to the encryption filter processing unit 120, and the encryption filter processing unit 120 receives it.

(3) Procedure for Generating Common Key (File Encryption Key) FIGS. 12 to 14 show a procedure for generating a common key (file encryption key). In FIG. 12, the client A logs on to the authentication service processing unit 120A together with the account information from the Web browser 110. The authentication service processing unit 120A (S27) owns the secret key a and the public key A in advance, acquires the public key W from the authentication server 300, and creates an arbitrary challenge code XA. Further, (S28) an identifier A of the client A is created from the challenge code XA, (S29) a client challenge 1 is created by encrypting the challenge code XA with the public key W, and (S30) session management of the identifier A of the client A Information is recorded and transmitted to the authentication server 300 via the Internet.

  The authentication unit 300A of the authentication server 300 (S31) decrypts the client challenge 1 with the secret key W and extracts the challenge code XA. (S32) creates an identifier W from this and the randomly created challenge code XW. Is recorded in the session management information.

  In FIG. 13, after the processing in FIG. 12, the authentication unit 300A creates (S33) a server challenge 2 in which the challenge code XW is encrypted with the public key A, and (S34) uses this server challenge 2, the identifier A, and the identifier W. It transmits to the authentication service processing unit 120A via the Internet. The authentication service processing unit 120A (S35) decrypts the server challenge 2 with the secret key a, and (S36) creates an identifier W from the challenge code XA and the challenge code XW, and this identifier W is the same as the received identifier W. (S37) The confirmed identifier W is registered in the session management information, and (S38) a common key k is created from the challenge code XA and the challenge code XW.

  The authentication unit 300A also creates a common key k from (S41) challenge code XA and challenge code XW. Thereafter, (S42) a logon response (with an identifier) is transmitted to the authentication service processing unit 120A via the Internet (S43), and the authentication service processing unit 120A transfers the logon response to the Web browser 110 as a logon response.

  In FIG. 14, after the processing of FIG. 13, authentication by the authentication service processing unit 120A and the authentication server 300 is transmitted with (S44) identifier information and nonce (plaintext and common key encryption), and the receiving side has an identifier. Confirm that it is registered in the session management information and that the plaintext nonce matches the decryption of the encrypted nonce.

  A nonce is a character string or number string used to prevent impersonation in authentication using a hash. In the above case, the identifier sent from the authentication server 300A and the server challenge 2 are combined, This is an authentication method by collecting and returning the hash. In this case, as long as a different nonce is used each time, the hash value is different from what has been used so far (with a very high probability), so safety is sufficiently ensured.

DESCRIPTION OF SYMBOLS 100 Client 200 Web file server 300 Authentication server 110 Web browser 120 Encryption filter processing part 130 Redirect driver 140, 240 Socket (Socket)
150, 250 SSL
210 Database 220 SQL Server 230 Database

Claims (10)

Electronic file management that encrypts the electronic files owned by the client and stores them on a Web file server, allowing the client to manage and use the electronic files, and only the third party authorized by the client to use the electronic files A system,
The client performs an authentication service by communication of an encrypted file with a Web browser that performs TCP / IP communication of a plain text file with the Web file server or another client, and communication with the authentication server. , File analysis, file encryption key generation, file encryption / decryption, public key / private key linkage management, and switching between the Web browser or encryption filter processing unit and the Web file server And a redirect driver that enables TCP / IP communication with the authentication server,
The Web file server includes an SQL server that executes management of writing / reading of an encrypted file to / from a database, and a Web server that enables HTTP communication of a plain text file with the client using TCP / IP. An electronic file management system.   2. The electronic file management system according to claim 1, wherein the client and the Web file server are provided with an SSL protocol for encrypting and transmitting / receiving a file for TCP / IP communication over a network.   The cryptographic filter processing unit performs hybrid authentication of a valid owner / legal successor of the encrypted file by using a public key authentication infrastructure and a fingerprint authentication token held in the individual authentication device. The electronic file management system according to claim 1, further comprising means for enabling startup. When a legitimate owner with individual authentication uses it personally without transferring it to others,
The encryption filter processing unit manages the file encryption key as an encryption pack (P key pack n) with the public key of the valid owner and transmits it to the Web server when the individual authentication of the valid owner succeeds. Means to
2. The electronic file management system according to claim 1, wherein the Web server includes means for displaying contents by managing an encrypted file and the P key pack n. When transferring an encrypted file held by a legitimate owner with individual authentication to another client,
The encryption filter processing unit, when succeeding in individual authentication of a valid owner, designates a “legitimate successor” to be transferred by a valid owner of an encrypted file with a certificate authority of the authentication server. The file encryption key is managed as an encryption pack (I key pack m) with the secret key / public key management mechanism executed in cooperation and the public key of the “legitimate successor” obtained from the certificate authority, and to the Web server Means for transmitting,
2. The electronic file management system according to claim 1, wherein the Web server includes means for displaying contents by managing the encrypted file and the I key pack m. A system configuration that enables network communication between a client, a Web file server, and an authentication server, encrypts an electronic file owned by the client, stores it in the Web file server, manages and uses the electronic file by the client itself, and An electronic file management method that allows only a third party authorized by the client to use the electronic file,
The encryption filter processing unit provided in the client encrypts the file Xn owned by the client itself and stores it in the database of the Web file server as a processing procedure (S1) with a common key kn created for each file registration process A step of encrypting Xn, (S2) a step of creating key possession information Ea obtained by encrypting a common key kn with a public key A acquired from an authentication server, and (S3) a file with a private key a previously owned A step of creating a signature Xn of Xn, (S4) a step of creating a cryptographic context C (kn, μ (Xn), S (Xn, a)), and (S5) of the key possession information Ea and the cryptographic context C Rewriting the HTTP packet and sending it to the web file server,
The Web file server includes: (S6) creating file management information; and (S7) sending a response message indicating completion of storage processing of the encrypted file to the client. Method. The encryption filter processing unit, as an acquisition processing procedure of the encrypted file stored by the client itself,
(S11) The client transmits a data acquisition request for the file Xn with the acquisition permission from the Web browser to the Web file server via the Internet, and the key ownership information Ea and the encryption are transmitted from the Web file server 200 as the data of the requested file. Capturing in the cryptographic filter processing unit in a set of contexts C;
(S12) obtaining encrypted data from the encryption context;
(S13) decrypting the common key kn with a secret key a previously owned;
(S14) decrypting the file Xn with the common key kn;
(S15) verifying the validity of the file Xn decrypted with the public key A and the signature Xn acquired from the authentication server;
The electronic file management method according to claim 6, further comprising: (S16) transferring the decrypted file Xn to the Web browser after correcting the HTTP packet and displaying the file. As an encryption key acquisition processing procedure for transferring a file from client A to client B,
When receiving the file transfer request to the client B (S17), the encryption filter processing unit of the client A transmits the designated data of the file owned by the client A to the client B to the management area of the Web file server via the Internet. And having a step to
The Web file server (S18) designating an encryption data area to be managed as file management information of the client A designated in the management area; and (S19) key ownership of the designated file in the encryption data area. A step of passing the key ownership information Ea to the management area of the information Ea and the encryption context C; (S20) in the management area, the key ownership information Ea encrypted with the public key A of the client A is obtained, and this key ownership Transmitting the information Ea to the encryption filter processing unit of the client A via the Internet,
The encryption filter processing unit that has received the key possession information Ea (S21) uses the secret key a to decrypt the common key kn, and (S22) uses the public key B of the client B acquired from the authentication server. 7. The electronic file management method according to claim 6, further comprising the step of creating key transfer information Eb obtained by encrypting the common key kn. As an encryption key transfer processing procedure for transferring a file from client A to client B,
The encryption filter processing unit of the client A that has acquired the key transfer information Eb encrypted with the public key B (S23) specifies the client B to be transferred and sends the key transfer information Eb to the Web file server via the Internet. A step of transmitting to the management area,
(S24) Key ownership information Ea managed in the encryption data area as file management information of the client A in the management area, and key transfer information encrypted with the public key B in the encryption context C area A step of adding Eb; (S25) file management information to which the key transfer information Eb has been added is created as file management information MB of the client B and stored in the management area 220A; (S26) a response message The electronic file management method according to claim 6, further comprising: transmitting to the encryption filter processing unit of the client A via the Internet. As a procedure for generating the common key (file encryption key),
The authentication service processing unit of the client A logged on with the account information (S27) owns the secret key a and the public key A in advance, acquires the public key W from the authentication server, and creates an arbitrary challenge code XA. (S28) creating an identifier A of the client A from the challenge code XA; (S29) creating a client challenge 1 in which the challenge code XA is encrypted with the public key W; and (S30) the client. Recording the identifier A of A in the session management information and transmitting it to the authentication server via the Internet,
The authentication unit of the authentication server (S31) decrypts the client challenge 1 with the secret key W and extracts the challenge code XA; and (S32) an identifier from the challenge code XA and the challenge code XW created at random Creating W, and recording the identifier W in session management information,
(S33) creating a server challenge 2 by encrypting the challenge code XW with a public key A (S33); (S34) processing the authentication service process with the server challenge 2, the identifier A, and the identifier W via the Internet Sending to the department,
The authentication service processing unit (S35) decrypts the server challenge 2 with a secret key a, and (S36) creates an identifier W from the challenge code XA and the challenge code XW, and the identifier W received by the identifier W And (S37) registering the confirmed identifier W in session management information, and (S38) creating a common key k from the challenge code XA and the challenge code XW. ,
(S41) creating a common key k from the challenge code XA and challenge code XW; and (S42) transmitting a logon response (with an identifier) to the authentication service processing unit via the Internet. Have
The authentication service processing unit has a step (S43) of transferring to the Web browser as a logon response,
After the generation of the common key (file encryption key), authentication by the authentication service processing unit and the authentication server is transmitted with (S44) identifier information and nonce (plaintext and common key encryption) added, and the receiving side uses the identifier. 7. The electronic file management method according to claim 6, further comprising a step of confirming that the plaintext nonce is registered with the session management information and that the plaintext nonce coincides with the decryption of the encryption nonce.

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