摘要:
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.
摘要:
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(Fq̂r), 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(Fq̂r) 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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.