Abstract: 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.

Abstract: According to one embodiment, a representation converting unit converts a set of n elements (h0, h1, . . . , hn?1) (hi: a member of a finite field Fp^m, 0?i?n?1) that is a projective representation of a member g of an n-th degree algebraic torus Tn(Fp^m) (n: positive integer, p: prime number, m: positive integer) into a limited projected representation expressed by a set of n elements (h?0, h?1, . . . , h?n?1) (h?i: a member of the finite field Fp^m, 0?i?n?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 Fp^m operation that is arithmetic operation in the finite field Fp^m based on a fact that an element in the set of n elements (h?0, h?1, . . . , h?n?1) represented by the limited projective representation is a zero element “0” or an identity element “1” when performing Fp^mn operation that is arithmetic operation of a finite field Fp^mn in combination with the Fp^m operation.

Abstract: 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.

Abstract: 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.

Abstract: When converting an affine representation representing a 2r-th degree algebraic torus T2r(Fq) (r is a prime number, and q is an integer) to a projective representation representing a quadratic algebraic torus T2(Fq^r), a representation converting apparatus acquires member (c0, c1, . . . , cr-2), (ci is a member of a finite field Fq, where 0?i?r?2) of a 2r-th degree algebraic torus T2r(Fq) 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 T2(Fq^r) is included in the 2r-th degree algebraic torus T2r(Fq), 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: According to one embodiment, a representation converting unit converts a set of n elements (h0, h1, . . . , hn?1) (hi: a member of a finite field Fp?m, 0?i?n?1) that is a projective representation of a member g of an n-th degree algebraic torus Tn(Fp?m) (n: positive integer, p: prime number, m: positive integer) into a limited projected representation expressed by a set of n elements (h?0, h?1, . . . , h?n?1) (h?i: a member of the finite field Fp?m, 0?i?n?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 Fp?m operation that is arithmetic operation in the finite field Fp?m based on a fact that an element in the set of n elements (h?0, h?1, . . . , h?n?1) represented by the limited projective representation is a zero element “0” or an identity element “1” when performing Fp?mn operation that is arithmetic operation of a finite field Fp?mn in combination with the Fp?m operation.

Abstract: 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.

Abstract: 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.

Abstract: A parameter generating device includes an input receiving unit that receives a degree n of an algebraic torus T including a group G in which a cryptosystem used in a torus-compressed public key cryptosystem is defined, a size W of a finite field F, and a size S of the group G, an extension-degree determining unit that determines an extension degree m of a finite field Fpm in which the algebraic torus T is defined, a first prime-number search unit that searches for a prime number p, a second prime-number search unit that searches for a prime number q, a test unit that checks whether a multiplication value nm is divisible by the prime number q, a security determining unit that determines that the cryptosystem is secure based on the multiplication value nm, and an output unit that outputs parameters when it is determined that the cryptosystem is secure.

Abstract: An input unit inputs encrypted data that elements of a subgroup and expressed in an affine representation. A transforming unit transforms the inputted encrypted data into projective representation data expressed in a projective representation. A plain data calculating unit subjects the projective representation data to a decrypting process previously defined by a cryptosystem, thereby calculating plain data expressed in the projective representation.

Abstract: When converting an affine representation representing a 2r-th degree algebraic torus T2r(Fq) (r is a prime number, and q is an integer) to a projective representation representing a quadratic algebraic torus T2(Fq?r), a representation converting apparatus acquires member (c0,c1, . . . ,cr?2), (ci is a member of a finite field Fq, where 0?i?r?2) of a 2r-th degree algebraic torus T2r(Fq) 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 T2(Fq?r) is included in the 2r-th degree algebraic torus T2r(Fq), 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.

Abstract: A decrypting apparatus that decrypts encrypted data that has been encrypted first data containing plain data, the encrypted data being represented by using an affine representation F_{p?m}×F_{p?m}?*(where p: a prime number; m: a natural number; and ?: exponentiation) obtains encrypted data represented in a vector format and a secret key corresponding to a public key and judges whether a vector component contained in the encrypted data is the affine representation F_{p?m}×F_{p?m}?*. Further, based on the result of the judging process, the decrypting apparatus maps the vector component onto each of the members of an algebraic torus by forming a decompression map and decrypts the encrypted data mapped onto each of the members of the algebraic torus, by using the secret key, therefore obtains the plain data.

Abstract: 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.

Abstract: In the method of the present invention, one of each pair of photons connected through entanglement is distributed to a transmitting station, relay stations and a receiving station. After the photons reach secure sites, such as the relay stations, a base for detecting photons is determined between adjacent sites, and then photons are detected in each site, which makes it possible to obtain a secret key used for secure information transmission between relay stations using bases coincide with each other every time. Also, in the present invention, a high-quality random number sequence serving as a secret key is automatically generated in a physical manner every time by detecting a superposition state of an entanglement and procedures corresponding to those in which a secret key itself is transmitted in a form of a quantum cryptogram are performed.

Abstract: A microscope includes a photon source which sequentially generates sets of quantum-mechanically entangled photons including at least two photons, a lens which focuses a set of photons, an actuator which varies a relative distance between a focal position of the lens and a specimen with a minute displacement, a detector detecting photons transmitted through or scattered by the specimen, and a counter counting coincidence detections of n-numbers of photons with the detector during a gating time which is set so that a rate that a number of photons detected during thereof belong to a single set of quantum-mechanically entangled photons exceeds a predetermined rate depending on the varied relative distance.

Abstract: In each stage, multiple parallel nonlinear transformation modules each perform local lower-level diffusion, then a diffusion module performs higher-level diffusion over the block width and multiple parallel nonlinear transformation modules each perform local lower-level diffusion. This operation is repeated a predetermined number of times corresponding to the number of stages. Each nonlinear transformation module is formed into the nested SPN structure by arranging alternately nonlinear transformation modules and a diffusion module. The diffusion module performs linear transformation for spreading the state of at least one bit in input data to the preceding nonlinear transformation modules to at least one bit in input data to the succeeding nonlinear transformation modules.

Abstract: An encryption apparatus for block data, comprises a first processing unit randomizing the block data in units of first portions obtained by dividing the block data, and a second processing unit diffusing the block data output from the first processing unit with respect to a second portion of the block data which is wider than the first portion. The first processing unit comprises first nonlinear processing units nonlinearly transforming the block data in units of the first portions. The second processing unit comprises a first linear diffusion processing unit linearly diffusing the second portion of the block data. At least one of the first nonlinear processing units comprises second nonlinear processing units nonlinearly transforming the block data in units of the first portions, and a second linear diffusion processing unit linearly diffusing the second portion of the block data.