Nec Corporation

Other

Sekisui Kagaku Kogyo Kabushiki Kaisha

Satoshi Obana

Toshinori Araki

Toshiyuki Isshiki

Kengo Mori

Jun Furukawa

Isamu Teranishi

Akihiro Tanaka

Kazue Sako

Yoshiharu Miura

Satoshi Shiroza

Tenji Sakata

Setsuo Komemushi

Mitsuo Okazaki

In a system with registration data, in a data registration phase, encrypted data is calculated by encrypting input data to be concealed by using a secret key and secret information, registration data is generated based on the encrypted data and verification key, and the registration data is stored as a registration template in a storage unit together with an identifier for uniquely identifying the registration data. In an encrypted text verification phase, a data verifying request is generated in which input data to be verified has been encrypted by using a random number and secret information, the registration template stored in the storage unit and the data verifying request are matched verified to produce a determined result, a verified result including a part or all of the registration template corresponding to the determined result is produced, and data is restored based on the verified result to produce a restored result.

Encrypted text verification system, method and recording medium

In a data registration phase, encrypted data is calculated by encrypting input data to be concealed by using a secret key, registration data is generated based on the encrypted data and a verification key, and the registration data is stored as a registration template in a storage unit together with an identifier for uniquely identifying the registration data. In an encrypted text verification phase, a data verifying request is generated in which input data to be verified has been encrypted by using a random number, the registration template stored in the storage unit and the data verifying request are verified to produce a determined result, a verified result including a part or all of the registration template corresponding to the determined result is produced, and data is restored based on the verified result to produce a restored result.

Encrypted text verification system, method, and recording medium

The present invention makes it possible, in encrypted data verification, to avoid the leaking of information related to the original plaintext, thereby ensuring safety. The system of the present invention is provided with: means (in FIG.) for generating first and second auxiliary data for verifying whether or not the Hamming distance of a plaintext between a first encrypted data in which input data is encrypted and is recorded in a storage device, and a second encrypted data obtained by encrypting input data of a target to be checked is equal to or less than a predetermined value; and means (andin FIG.) for taking the difference between the first encrypted data recorded in the storage device, and the second encrypted data, and determining, using the first and second auxiliary data, whether or not the Hamming distance of the plaintext corresponding to the difference between the first encrypted data and the second encrypted data is equal to or less than the predetermined value.

Encrypted data verification system, method and recording medium

Provided a database apparatus comprising a control means to execute data access control on a database, wherein the control means, receiving a database operation command from a user apparatus, comprises, regarding data and/or metadata to be handled associated with the database operation command, means for executing database operation or computation on encrypted data and/or encrypted metadata as is in ciphertext and means for executing database operation or computation on plaintext data and/or plaintext metadata, and the control means sends a processing result to the user apparatus.

Database apparatus, method, and program

A user apparatus connected to database apparatus via network comprises: unit that manages key information in order to encrypt and decrypt; storage unit that stores security configuration information of data and/or metadata; application response unit that determines whether or not encryption is necessary for database operation command, and if encryption is necessary, selects encryption algorithm corresponding to data and/or metadata, performs encryption, and transmits result to database control unit to cause database control unit to execute database operation, if encryption is not necessary, transmits database operation command to database control unit to cause database control unit to execute database operation, and receives processing result transmitted by database control unit, and if decryption or conversion of data and/or metadata of processing result is necessary, performs necessary decryption or conversion, and returns response to database operation command; and security configuration unit that configures security information of data stored in database.

Database encryption system, method, and program

Secret information is encoded/distributed into distributed information according to access structure, a random number sequence corresponding to number of pieces into which the secret information is distributed is generated by randomly selecting polynomial coefficients, the coefficients are encoded/distributed into random number information according to access structure, a hash function whose hash values correspond to the random number sequence is generated, keys for which the hash function applies are selected so as to individually set data for checking whether restored secret information is being manipulated as number of pieces of check data corresponding to number of pieces into which the secret information is distributed, the distributed information is read, the secret information is restored; the random number information is read, the random number sequence is restored, the check data is read, and the restored secret information is judged as not being manipulated when the read check data satisfies the hash function.

Secret information distribution system, secret information distribution method and program

A verification device, upon the input of any k items of shared information among n items of shared information and 't': generates as subsets all combinations that select r items of shared information among the k items of shared information received as input where r satisfies r&#x2267;t+2; for each of the subsets, uses the cheater-identification information belonging to the subset to judge whether dishonest shared information is included in the subset; and based on the judgment results, generates and supplies as output a cheater set indicating dishonest shared information among the k items of shared information.

Verification device, secret information restoration device, verification method, program, and secret sharing system

A share generation apparatus () generates check data corresponding to a secret and random number, shares and encodes the secret and random number in accordance with a predetermined access structure, and stores them in storage devices (to). A reconstruction apparatus () reads out the shared/encoded secret and random number from the storage devices corresponding to members of the access structure, and reconstructs them. If the check data correspond to the reconstructed secret and random number, it is determined that the reconstructed secret is correct. If not, it is determined that cheating has occurred. Cheating of forging some shares by referring to (n&#x2212;1) shares can be detected regardless of a distribution used to select a secret.

Share generation apparatus, reconstruction apparatus, verification apparatus, and secret sharing system

There is disclosed a system for identifying falsified secret information shares included in k secret information shares used to recover secret information according to a (k,n)-threshold secret sharing scheme, and producing falsified secret information shares of reduced size. A shared information generating apparatus generates cheater identifying information Ai(i=1, 2, . . . , n) using n secret information shares Vi generated according to the (k,n)-threshold secret sharing scheme and random polynomials. A recovering apparatus detects cheated secret information shares using the arbitrary k secret information shares and k cheater identifying information, and recovers the secret information from the k secret information shares if it detects no cheated secret information shares.

Shared information generating apparatus and recovering apparatus

A system for disabling an unauthorized person includes an encryption device () and a decryption device (). The encryption device () stores distribution member set data, a random number, and a public key, the distribution member set data being information on members who are permitted to decrypt a cyphertext, and generates and distributes, when a shared key is input, an error-containing cyphertext which is a cyphertext containing the shared key, the distribution member set data, and error information different for each of the members, and an error correction cyphertext which is a cyphertext of the error information. The decryption device () is connected to the encryption device, stores the public key and a secret key corresponding to the own device, determines, upon reception of the error-containing cyphertext and the error correction cyphertext from the encryption device, whether the own device is included in the distribution member set data, decrypts, if the own device is included in the distribution member set data, the error-containing cyphertext and the error correction cyphertext with the public key and the secret key, and removes the error information from the decrypted error-containing cyphertext to output the shared key.

System for disabling unauthorized person, encryption device, encryption method, and program

Check data corresponding to distributed confidential information is generated, and the confidential information and check data are distribution-coded. When the confidential information is restored, the confidential information and check data are restored and it is determined whether or not the restored check data correspond to the restored confidential information. If the data correspond to the information, the information is determined to be correct and is output. If not, the information is judged to be false (i.e., tampered distributed information), and a symbol indicating that falsity has been detected is output.

Distributed information generator and restoring device

An input data enlarging unit () derives a first enlargement unit output and a second enlargement unit output that are uniquely specified by input data () to output the same. The first enlargement unit output and the second enlargement unit output are elements of output data set B which forms a group. An &#x3b5;&#x2212;&#x394; hash function calculation unit () receives as input the first enlargement unit output to calculate an h&#x394; function which is specified by hash-function-specifying data () and an element of the H&#x394; function set. The function set H&#x394; is such that the number of h&#x3b5;H &#x394; which satisfies h(x)&#x2212;h(y)=d for an arbitrary element d of the output data set B and two different elements x and y of the output data set B is equal to or smaller than |H&#x394;|&#xb7;&#x3b5;. An adding unit () adds together the result of calculation of the function H&#x394; and the second enlargement unit output to output a result of the addition.

Universal-hash-function-family calculation unit and shared-key generation system

A signature calculation system includes: a mobile agent for calculating a digital signature of the owner of the mobile agent; a base host of the mobile agent from which the mobile agent starts moving in a network; and remote hosts in the network which can be visited by the mobile agent. In the base host in which the mobile agent is activated, a secret key #of the owner of the mobile agent is partitioned and distributed into cipher texts (partial signature auxiliary data) that can be restored only when calculations by use of secret keys of k remote hosts are executed, and data including the cipher texts are stored in the mobile agent. A remote host visited by the mobile agent arbitrarily presents signature target data. If the mobile agent determined to write a digital signature for the signature target data, the mobile agent stores the signature target data and moves to the next remote host. Thereafter, each remote host visited by the mobile agent calculates a partial signature by use of the data stored in the mobile agent and a secret key of the remote host. After the mobile agent visited k remote hosts since the presentation of the signature target data, the mobile agent returns to the remote host that presented the signature target data, at which the digital signature for the signature target data by use of the secret key of the owner of the mobile agent is obtained from the partial signatures calculated by the k remote hosts.

Signature calculation system by use of mobile agent

A zero-knowledge proving system includes a proving mechanism for proving equality or inequality of two discrete logarithms and a verifying mechanism for verifying said equality or inequality. The proving mechanism stores public information including a designated operation scheme, two input numbers &#x3b1; and &#x3b2;, and two predetermined bases g and h, private information x which is a discrete logarithm of &#x3b1; to the base g. After converting &#x3b1;, &#x3b2; and h to produce &#x3b1;', &#x3b2;&#x2032; and &#x3b3;&#x2032; as follows: &#x3b1;&#x2032;=&#x3b1;; &#x3b2;&#x2032;=&#x3b2;; and &#x3b3;&#x2032;=h, the equality of a log&#x3b1;&#x2032; and log&#x3b2;&#x2032; and the equality of log&#x3b1;&#x2032; and log&#x3b3;&#x2032; are proved. The verifying mechanism verifies the equality of a log&#x3b1;&#x2032; and log&#x3b2;&#x2032; and the equality of log&#x3b1;&#x2032; and log&#x3b3;&#x2032;. Then, the received &#x3b2;&#x2032; and &#x3b3;&#x2032; are checked to determine the equality or inequality thereof, and it is determined whether the proof is acceptable, depending on the verification and the check results.

Growing community of inventors

Tokyo, Japan

Satoshi Obana