Mitsubishi Electric Corporation

Mitsubishi Electric Research Laboratories, Inc.

Takato Hirano

Yutaka Kawai

Nori Matsuda

Mitsuhiro Hattori

Yoshihiro Koseki

Takashi Ito

Takumi Mori

Satoshi Yasuda

Rina Shimizu

Ye Wang

Yoichi Shibata

Akihiro Miura

Kenichiro Hayasaka

Sachihiro Ichikawa

Tsutomu Sakagami

Kazuhiro Kusunoki

A searchable encryption system includes a registration device including an index generation unit () and an encrypted index generation unit (). The index generation unit () generates a registration keyword index by using a registration keyword, authorized-person attribute information corresponding to an authorized person who has an authority to search for the registration keyword, a user key function to generate a user key corresponding to a searcher, a search query function to generate a search query having the user key incorporated therein, and an index query function to generate an index query having the search query incorporated therein. The encrypted index generation unit () generates an encrypted index by encrypting the registration keyword index by using the index disclosure key.

Searchable encryption system, searchable encryption method, and non-transitory computer-readable recording medium

A registration device () generates ciphertext data using a new data key, generates an encrypted keyword using a new keyword key, and registers a set of the ciphertext data and the encrypted keyword. A search operation device () restores an old data key from the new data key, restores an old keyword key from the new keyword key, and generates a new search query and an old search query, using the new keyword key and the old keyword key, respectively. A data management device () finds an encrypted keyword that matches one of the new search query and the old search query, and outputs an encrypted search result including ciphertext data corresponding to the encrypted keyword that has been found. The search operation device decrypts a plaintext from the ciphertext data included in the encrypted search result, using one of the new data key and the old data key.

Searchable encryption system

A registration device () accepts plaintext, attribute information of a user having an authority of referring to the plaintext, and a registration key for use in generating a user key for generating a search query. The registration device generates aggregate information indicating one or more aggregate values, by aggregating a plurality of attribute values included in the attribute information. The registration device generates generalized information indicating a plurality of generalized values for each aggregate value by generalizing each aggregate value included in the aggregate information. The registration device generates ciphertext data including the plaintext encrypted, by using the plaintext, the attribute information, the generalized information, and the registration key. The registration device registers the ciphertext data in a database.

Registration device, search operation device, and data management device

A registration device () generates an encryption keyword by encrypting a keyword with a registration key, generates an index including the encryption keyword and identification information which identifies a corresponding ciphertext, generates a conversion key from the registration key and a search key, and registers a plurality of ciphertexts, the index, and the conversion key in a server device (). A search device () generates a search query by encrypting a keyword, and transmits the search query to the server device (). The server device () generates a re-encryption keyword by re-encrypting the search query with the registered conversion key, searches the registered index with the re-encryption keyword, acquires, from the index, the identification information if the encryption keyword is obtained as a search result, extracts a ciphertext identified by the identification information from the registered plurality of ciphertexts, and transmits the extracted ciphertext to the search device ().

Registration device, server device, searchable encryption system, and searchable encryption method

An encryption device () generates a ciphertext ct encrypted from information x with using an encryption token etk. A decryption key generation device () generates a decryption key dk from a user secret key sk in which a vector y is set, with using a decryption token dtk corresponding to the encryption token etk. A privacy-preserving analysis device () decrypts the ciphertext ct generated by the encryption device (), by means of the decryption key dk generated by the decryption key generation device (), so as to generate a result of computation over the vector x and the vector y.

Privacy-preserving analysis device, privacy-preserving analysis system, privacy-preserving analysis method, and computer readable medium

A registration apparatus generates a data random number tuple R that is a tuple of random numbers whose quantity is the same as a level quantity L of a hierarchy that a user attribute forms, and that is also a tuple of uniformly random numbers. Also, the registration apparatus accepts a plaintext M and attribute information B. The registration apparatus executes a function F_2 by taking as input a concatenated value of an attribute value of each level j in the attribute information B and a number of each level j, executes a function F_3 by taking as input a function value of the function F_2, calculates an attribute element C_{j, 0, 0} that is an exclusive-or of a function value of the function F_3 and a jth random number of the data random number tuple R, executes a function F_4 by taking as input the plaintext M and an exclusive-or of the data random number tuple R, and generates encrypted data C that includes the attribute element C_{j, 0, 0} and a ciphertext C_{L+1} which is a function value of the function F_4. Then, the registration apparatus registers the encrypted data C in a data management apparatus.

Registration apparatus, search operation apparatus, data management apparatus

A random-number generation unit generates a plurality of random numbers from a plurality of seeds. A data scrambling unit conceals concealment target data which is a concealment target by using the plurality of random numbers generated by the random-number generation unit. A transmission unit transmits concealed data which is the concealment target data concealed by the data scrambling unit to a data analysis device, and transmits any seed among the plurality of seeds to the data analysis device, after transmission of the concealed data to the data analysis device.

Concealment device, data analysis device, and computer readable medium

A data partition unit partitions character string data D into N pieces of element data w, w, . . . , wfrom a front to an end of the character string data D. A partial character string generation unit generates a set A={A, A, . . . , A} and an element A={(w), (ww), . . . , (ww. . . w)} of the set A where i=1, . . . , N, from the element data w, w, . . . , w. A position information assignment unit generates a set B={B, B, . . . , B} and an element B={(i, w, (i, ww), . . . , (i, ww. . . w)} of the set B by associating each of (w), (ww), . . . , (ww. . . w) which are components of the element Awith position information i. An encryption unit encrypts each of (i, w), (i, ww), . . . , (i, ww. . . w) which are components included in the element B.

Encryption device, encryption method, computer readable medium, and storage device

A registration destination determination device () determines which data management device, among a plurality of data management devices (A,B), is to manage registration data, such that, with a data type constituting the registration data as a target type, an appearance frequency distribution of values set for the target type of the registration data managed by each of the plurality of data management devices (A,B) is different from an appearance frequency distribution of values set for the target type of the registration data managed by the whole of the plurality of data management devices (A,B).

Registration destination determination device, searchable encryption system, destination determination method, and computer readable medium

A management apparatus () stores encrypted tags (C(D)) and encrypted data such that they are associated with each other. When a search apparatus () obtains a search keyword (s) for searching for encrypted data stored in the management apparatus (), the search apparatus () calculates deterministic information (t) which is uniquely determined by the search keyword (s), and generates a search query (Q(s)) by performing encryption of a probabilistic encryption scheme on the search keyword (s) using the deterministic information (t). The search apparatus () transmits the search query (Q(s)) to the management apparatus (). When the management apparatus () receives the search query (Q(s)) from the search apparatus (), the management apparatus () determines whether the search keyword (s) obtained by decrypting the search query (Q(s)) matches an associated keyword obtained by decrypting an encrypted tag (c) stored in the management apparatus ().

Secret search system, secret search method, and computer readable medium

An encryption device () includes an encryption unit (), a detection element generation unit (), and a transmission unit (). The encryption unit () encrypts a plain text by using one of a pair of keys to generate an encrypted text into which the plain text has been encrypted and which can be subjected to homomorphic computation. The detection element generation unit () generates a detection element E used to detect a change in the encrypted text by using the one key and the encrypted text. The transmission unit () transmits the encrypted text and the detection element.

Encrypted text conversion device, computer readable medium, and encryption text conversion method

A data search server stores a system ciphertext including a data ciphertext and a keyword ciphertext in each category-specific DB unit for each data category, and stores each category-determination secret key being associated with each category-specific DB unit. A search request receiving unit receives from a data search terminal a search request including a search trapdoor and an index tag. A data searching unit searches for a category-determination secret key with which the index tag is decrypted to the same value as a key-determination value. Using the search trapdoor, the data searching unit performs a search of a Public-key Encryption with Keyword Search scheme on system ciphertexts in a category-specific DB unit associated with this category-determination secret key. A search result transmitting unit transmits to the data search terminal a data ciphertext included in a system ciphertext which has been found as a hit in the search.

Data search device, data search method, computer readable medium storing data search program, data registration device, data registration method, computer readable medium storing data registration program, and information processing device

Using three pieces of element data w, w, and wobtained by partitioning storage data D, an encryption unit generates three sets of a first set Ain which the first to third pieces of element data are sequentially arranged, a second set Ain which the second to third pieces of element data are sequentially arranged, and a third set Acomposed of the third piece of element data. The encryption unit encrypts each piece of element data included in each set with a random number Rby a CBC mode.

Encryption device, search device, computer readable medium, encryption method, and search method

The present invention is provided with an encryption similarity calculation unit to calculate an encryption similarity being a similarity degree between storage data and search data encrypted using a homomorphic encryption, by performing a homomorphic operation on storage encryption data being the storage data encrypted using the homomorphic encryption, and search encryption data being the search data encrypted using the homomorphic encryption, the search data being used in search of the storage data, and an encryption result transmission unit to generate an encryption search result to represent whether or not the similarity degree is not more than a threshold value &#x3b8; by using the encryption similarity, and to transmit the encryption search result to a search device.

Secret search system, management device, secret search method and computer readable medium

In a server apparatus, a data storage part stores a plurality of pieces of encrypted data. An index storage part stores, as an index I, a data structure which is for performing search with using a function H that outputs a unique numeric value in response to an inputted keyword, the data structure having a plurality of storage areas corresponding, in one-to-one relation, to numeric values outputted from the function H, and storing, for a plurality of keywords corresponding to plaintext data, an identifier of encrypted data being post-encryption data of the plaintext data to which each keyword corresponds, in a storage area corresponding to the numeric value outputted from the function H when each keyword is inputted. A search part inputs one of the plurality of keywords to the function H, identifies a storage area corresponding to the numeric value outputted from the function H, from the index I, and acquires encrypted data corresponding to the identifier stored in the identified storage area, from the data storage part.

Server apparatus, search system, terminal apparatus, search method, non-transitory computer readable medium storing server program, and non-transitory computer readable medium storing terminal program

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Tokyo, Japan

Takato Hirano