Kabushiki Kaisha Toshiba

Digital Vision Laboratories Corporation

Hirofumi Muratani

Kenji Ohkuma

Yoshikazu Hanatani

Tomoko Yonemura

Taichi Isogai

Kenichiro Furuta

Atsushi Shimbo

Yuichi Komano

Toru Kambayashi

Shinichi Kawamura

Tomoo Yamakage

Hisashi Yamada

Fumihiko Sano

Hanae Ikeda

Shinichiro Koto

Takashi Ida

Akira Morishita

Satoshi Ito

Ichiro Tomoda

Masafumi Kondo

Toshiya Takahashi

Yasuhiko Shimomura

Shigehiro Asano

Miwako Doi

Tomoya Kodama

Yoshihiro Ohmori

Shuichi Tsujimoto

Seiji Miike

Masahiko Motoyama

Naoki Endo

Jiro Amemiya

Taku Katoh

Tomohisa Hamakawa

Akihiro Muto

Shouzou Isobe

Ben Smyth

Tooru Kambayashi

According to an authentication device is for authenticating the validity of a subject ciphertext generated by encrypting a plaintext using homomorphic encryption. The authentication device includes a commitment generator and a response generator. The commitment generator is configured to generate a commitment from a randomly selected verification value, and transmit the commitment to a verification device for verifying the validity of the subject ciphertext. The response generator is configured to generate a response value generated by computing from an acquired challenge value, the plaintext, and the verification value, and transmit the response value to the verification device. The response generator is configured to generate the response value by a third operation where a result of a first operation using the response value is equal to a result of processing the challenge value, the subject ciphertext, and the commitment by a second operation.

Authentication device, output device, verification device and input device

According to an embodiment, a computing device includes a receiving unit, a calculating unit, a solving unit, a selecting unit, and a determining unit. The receiving unit is configured to receive pieces of input data indicative of elements of a subgroup of a multiplicative group in a finite field and pieces of first additional data for identifying conjugates of the respective pieces of input data. The elements are represented by traces. The calculating unit is configured to calculate a coefficient of an equation based on the pieces of input data. The solving unit is configured to obtain solutions of the equation. The selecting unit is configured to select one of the solutions as a result of computation, based on the first additional data. The determining unit is configured to determine second additional data for identifying a conjugate of the selected result of computation based on the first additional data.

Public key cryptography computing device

According to one embodiment, a decompressing apparatus includes an input unit, a calculating unit, a first selecting unit, and a decompressing unit. The input unit inputs additional data, which is obtained based on trace expression data in which an element in a subgroup of a multiplicative group of a finite field is trace-expressed and affine expression data in which the trace expression data is affine-expressed, and the trace expression data. The calculating unit calculates a plurality of solutions of simultaneous equations derived by the trace expression data. The first selecting unit selects any of a plurality of items of affine expression data in which the element is affine-expressed based on the additional data, the affine expression data being found from the solutions. The decompressing unit decompresses the selected affine expression data to the element.

Decompressing apparatus and compressing apparatus

An arithmetic device includes an input unit inputting data that are elements of a group; a converting unit is configured, when the input data are in a second representation, to convert the input data into a first representation and to perform arithmetic operation on the converted first representation using an operand in the first representation in which at least one subcomponent is a zero element to convert the converted first representation into first converted data expressed in the first representation, and when the input data are in the first representation, to perform arithmetic operation on the input data using the operand in the first representation in which at least one subcomponent is a zero element to convert the input data into second converted data expressed in the first representation; and an operating unit that performs arithmetic processing on the first or the second converted data using secret information.

Arithmetic device, method, and program product

According to one embodiment, a representation converting unit converts a set of n elements (h, h, . . . , h) (h: a member of a finite field F, 0&#x2266;i&#x2266;n&#x2212;1) that is a projective representation of a member g of an n-th degree algebraic torus T(F) (n: positive integer, p: prime number, m: positive integer) into a limited projected representation expressed by a set of n elements (h', h&#x2032;, . . . , h&#x2032;) (h&#x2032;: a member of the finite field F, 0&#x2266;i&#x2266;n&#x2212;1) in which at least one element out of the n elements is a zero element 0 or an identity element 1. An arithmetic unit omits part of Foperation that is arithmetic operation in the finite field Fbased on a fact that an element in the set of n elements (h&#x2032;, h&#x2032;, . . . , h&#x2032;) represented by the limited projective representation is a zero element '0' or an identity element '1' when performing Foperation that is arithmetic operation of a finite field Fin combination with the Foperation.

Arithmetic device

A compressing unit compresses an element on an algebraic torus into affine representation according to a compression map. A determining unit determines whether a target element on the algebraic torus to be compressed is an exceptional point representing an element on the algebraic torus that cannot be compressed by the compression map. The compressing unit generates, when it is determined that the target element is the exceptional point, a processing result including exceptional information indicating that the target element is the exceptional point, and generates, when it is determined that the target element is not the exceptional point, a processing result including affine representation obtained by compressing the target element according to the compression map.

Apparatus for performing data compression processing using algebraic torus

In a computing device that calculates a square of an element in a finite field, a vector representation of the element in the finite field is accepted. The vector representation includes a plurality of elements. The computing device performs a multiplication operation on a base field using the accepted elements, and obtains a multiplication value. The multiplication operation is determined by a condition under which the element in the finite field is placed in an algebraic torus. The computing device performs an addition and subtraction operation using the obtained multiplication value and the accepted elements, and obtains a calculation result of the square of the element. The addition and subtraction operation is determined by the condition. The computing device then outputs the calculation result.

Exponentiation calculation apparatus and method for calculating square root in finite extension field

When converting an affine representation representing a 2r-th degree algebraic torus T(F) (r is a prime number, and q is an integer) to a projective representation representing a quadratic algebraic torus T(F), a representation converting apparatus acquires member (c, c, . . . , c), (cis a member of a finite field F, where 0&#x2266;i&#x2266;r&#x2212;2) of a 2r-th degree algebraic torus T(F) represented by the affine representation. The apparatus performs a multiplication operation on the acquired member. The multiplication operation is determined by a condition under which a member of a quadratic algebraic torus T(F) is included in the 2r-th degree algebraic torus T(F), a modulus and a base of a quadratic extension, and a modulus and a base of an r-th degree extension. The representation converting apparatus then performs an addition and subtraction operation determined by the condition, the moduli, and the bases.

Representation converting apparatus, arithmetic apparatus, representation converting method, and computer program product

An encryption processing unit executes an arithmetic operation decided in advance and outputs an arithmetic result as an element on an algebraic torus. A compressing unit outputs, when the arithmetic result is an exceptional point representing an element on the algebraic torus that cannot be compressed by a compression map for compressing an element on the algebraic torus into affine representation, a compression result obtained by compressing the arithmetic result according to the compression map and outputs, when the arithmetic result is the exceptional point, an element belonging to a specific set decided in advance that does not overlap a set to which a compression result obtained by compressing the arithmetic result, which is not the exceptional point, belongs.

Apparatus and computer program product for performing data compression processing using algebraic torus

A digital watermark embedding apparatus for embedding watermark information into a digital content, obtains a predetermined topological invariant corresponding to the watermark information to be embedded into the digital content, and sets the predetermined topological invariant to the digital content by modifying the digital content into which the watermark information is to be embedded.

Digital watermark embedding apparatus, digital watermark detecting apparatus, digital watermark embedding method, digital watermark detecting method and computer program product

A digital watermark embedding apparatus comprises an acquisition unit configured to acquire a topological invariant as digital watermark information, key information corresponding to the digital watermark information, and a target content in which the digital watermark information is to be embedded, function generation unit configured to generate a topological function corresponding to the topological invariant, a randomizing-function generation unit configured to generate a randomizing function based on the key information, and compute a composite function by composition of the randomizing function and the topological function, and a function-embedding unit configured to embed the composite function in the target content.

Digital watermark embedding apparatus, method and program, and digital watermark detection apparatus, method and program

Residue calculating sections respectively obtain residues which take a plurality of integers as modulus, with respect to a user ID. The plurality of integers are stored in modulus storage sections and are prime to each other. Based on these residues and parameters stored in a coding parameter storage section, component codes constructed by continuous sequences of 1 and 0 using a predetermined number of bits as a unit are respectively generated by component code generating sections. These component codes are concatenated by a concatenating section, thereby to obtain a code to be embedded, which constructs watermark information.

Code generating method and unit thereof, code detecting method and unit thereof, and watermark embedding unit and watermark detecting unit

A digital watermark embedding apparatus comprises below units. A first generation unit generates a plurality of symbol sequences each of which includes a plurality of symbols including ranks, each of the ranks being uniquely numbered among each of the symbol sequences, each of the symbol sequences uniquely corresponding to each of a plurality of identification information items to be embedded as digital watermark information into each of copies of digital contents. A second generation generates a plurality of to-be-embedded codes corresponding to each of the symbols in each of the symbol sequences. An embedding unit embeds the to-be-embedded codes in each of the copies.

Digital watermark embedding apparatus and method, and digital watermark analysis apparatus, method and program

A rendering device to render a contents data comprises a reader, an information acquisition unit and a controller. The reader reads the contents data. The information acquisition unit acquires a copy control information. The controller controls rendering of the contents data while updating the acquired copy control information.

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Kawasaki, Japan

Hirofumi Muratani