US 9,871,652 B2 · Cryptographic processing method and cryptographic processing device

Abstract

A computer generates a third encrypted polynomial that corresponds to a result of encrypting a third polynomial by use of a result of multiplying a first encrypted polynomial by a second encrypted polynomial, and outputs cryptographic information that represents the third encrypted polynomial. The first encrypted polynomial is a polynomial obtained by encrypting a first polynomial that corresponds to a first vector, and the second encrypted polynomial is a polynomial obtained by encrypting a second polynomial that corresponds to a second vector. The third polynomial includes a first term that has a coefficient based on an inner product of the first vector and the second vector and a second term other than the first term, in which a coefficient of the second term is masked.

Claims15

Dependent claims

A cryptographic processing method comprising:

generating a third encrypted polynomial that corresponds to a result of encrypting a third polynomial by a computer, by use of a result of multiplying a first encrypted polynomial obtained by encrypting a first polynomial that corresponds to a first vector by a second encrypted polynomial obtained by encrypting a second polynomial that corresponds to a second vector, the third polynomial including a first term that has a coefficient based on an inner product of the first vector and the second vector and a second term other than the first term, wherein the computer masks a coefficient of the second term by performing cryptographic masking on the result of multiplying the first encrypted polynomial by the second encrypted polynomial;
and
outputting cryptographic information that represents the third encrypted polynomial.

A cryptographic processing device comprising:

a memory;
and
a processor coupled to the memory and that generates a third encrypted polynomial that corresponds to a result of encrypting a third polynomial by use of a result of multiplying a first encrypted polynomial obtained by encrypting a first polynomial that corresponds to a first vector by a second encrypted polynomial obtained by encrypting a second polynomial that corresponds to a second vector, the third polynomial including a first term that has a coefficient based on an inner product of the first vector and the second vector and a second term other than the first term, wherein the processor masks a coefficient of the second term by performing cryptographic masking on the result of multiplying the first encrypted polynomial by the second encrypted polynomial;
and
a communication interface coupled to the memory and the processor and that outputs cryptographic information that represents the third encrypted polynomial.

2 more elements

A non-transitory computer-readable recording medium having stored therein a cryptographic processing program that causes a computer to execute a process comprising:

generating a third encrypted polynomial that corresponds to a result of encrypting a third polynomial by use of a result of multiplying a first encrypted polynomial obtained by encrypting a first polynomial that corresponds to a first vector by a second encrypted polynomial obtained by encrypting a second polynomial that corresponds to a second vector, the third polynomial including a first term that has a coefficient based on an inner product of the first vector and the second vector and a second term other than the first term, wherein the computer masks a coefficient of the second term by performing cryptographic masking on the result of multiplying the first encrypted polynomial by the second encrypted polynomial;
and
outputting cryptographic information that represents the third encrypted polynomial.

Dependencies are inferred from the claim text.

Cryptographic processing method and cryptographic processing device

Life of this patent

Cryptographic processing method and cryptographic processing device

Life of this patent

Abstract

Claims15