Cryptographic processing device and cryptographic processing method

Patent metadata

Field	Value
Publication number	US-9960905-B2
Application number	US-201615058677-A
Country	US
Kind code	B2
Filing date	Mar 2, 2016
Priority date	Mar 10, 2015
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

A cryptographic processing device includes a processor that generates a first encrypted polynomial, a receiver that receives cryptographic information representing a fourth encrypted polynomial, and cryptographic information representing a second random number, the fourth encrypted polynomial including a first operation result that is a result of an operation of a fifth vector and a sixth vector, the first operation result being obtained by a second encrypted polynomial and a third encrypted polynomial, wherein the second encrypted polynomial is obtained based on the first encrypted polynomial, the second random number, and a second polynomial that corresponds to a third vector obtained by adding zero to the second vector, and the third encrypted polynomial is obtained based on the fifth vector obtained by adding zero to a fourth vector. The processor generates a second operation result that is a result of an operation of the second vector and the fourth vector.

First claim

What is claimed is:

1. A cryptographic processing with or in device comprising: a processor that generates a first encrypted polynomial by encrypting a first polynomial that corresponds to a first vector obtained by adding a first random number generated by the cryptographic processing device to a zero vector as a component; a transmitter that transmits, to a terminal, first cryptographic information that represents the first encrypted polynomial; and a receiver that receives, from a calculation device, second cryptographic information that represents a fourth encrypted polynomial, and receives, from the calculation device, third cryptographic information that represents a second random number generated by the terminal, the fourth encrypted polynomial including a first operation result that is a result of an operation of a fifth vector and a sixth vector that is obtained by adding, to a second vector, a result of a multiplication of the first random number by the second random number as a component, the first operation result being obtained by calculating from a second encrypted polynomial and a third encrypted polynomial, wherein the second encrypted polynomial is obtained by adding a result of a multiplication of the first encrypted polynomial by the second random number to a second polynomial that corresponds to a third vector obtained by adding zero to the second vector as a component, and the third encrypted polynomial is obtained by encrypting a third polynomial that corresponds to the fifth vector obtained by adding zero to a fourth vector as a component, wherein the processor decrypts the second cryptographic information and the third cryptographic information, and generates a second operation result that is a result of an operation of the second vector and the fourth vector, on the basis of a result of decrypting the second cryptographic information and a result of decrypting the third cryptographic information, wherein the processor uses the result of the decrypting the second cryptographic information and a result of decrypting the third cryptographic information to prevent replay attacks.

2. The cryptographic processing device according to claim 1 , wherein
the first operation result represents a Hamming distance between the fifth vector and the sixth vector, and
the second operation result represents a Hamming distance between the second vector and the fourth vector.

3. The cryptographic processing device according to claim 1 , wherein
the third cryptographic information represents an encrypted inverse obtained by encrypting an inverse of the second random number, and
the processor calculates the second random number from an inverse of the second random number, the inverse being a result of decrypting the third cryptographic information, and subtracts the result of the multiplication of the first random number by the second random number from the first operation result, so as to obtain the second operation result.

4. A cryptographic processing method comprising: generating, by a cryptographic processing device, a first encrypted polynomial by encrypting a first polynomial that corresponds to a first vector obtained by adding a first random number generated by the cryptographic processing device to a zero vector as a component; transmitting, by the cryptographic processing device, to a terminal, first cryptographic information that represents the first encrypted polynomial; receiving, by the cryptographic processing device, from a calculation device, second cryptographic information that represents a fourth encrypted polynomial, and receiving, by the cryptographic processing device, from the calculation device, third cryptographic information that represents a second random number generated by the terminal, the fourth encrypted polynomial including a first operation result that is a result of an operation of a fifth vector and a sixth vector that is obtained by adding, to a second vector, a result of a multiplication of the first random number by the second random number as a component, the first operation result being obtained by calculating from a second encrypted polynomial and a third encrypted polynomial, wherein the second encrypted polynomial is obtained by adding a result of a multiplication of the first encrypted polynomial by the second random number to a second polynomial that corresponds to a third vector obtained by adding zero to the second vector as a component, and the third encrypted polynomial is obtained by encrypting a third polynomial that corresponds to the fifth vector obtained by adding zero to a fourth vector as a component; decrypting, by the cryptographic processing device, the second cryptographic information and the third cryptographic information; and generating, by the cryptographic processing device, a second operation result that is a result of an operation of the second vector and the fourth vector, on the basis of a result of decrypting the second cryptographic information and a result of decrypting the third cryptographic information, wherein the processor uses the result of the decrypting the second cryptographic information and a result of decrypting the third cryptographic information to prevent replay attacks.

5. The cryptographic processing method according to claim 4 , wherein
the first operation result represents a Hamming distance between the fifth vector and the sixth vector, and
the second operation result represents a Hamming distance between the second vector and the fourth vector.

6. The cryptographic processing method according to claim 4 , wherein
the third cryptographic information represents an encrypted inverse obtained by encrypting an inverse of the second random number, and
the generating the second operation result calculates the second random number from an inverse of the second random number, the inverse being a result of decrypting the third cryptographic information, and subtracts the result of the multiplication of the first random number by the second random number from the first operation result, so as to obtain the second operation result.

7. A non-transitory computer-readable recording medium having stored therein a cryptographic processing program for causing a computer to execute a process, the process comprising: generating a first encrypted polynomial by encrypting a first polynomial that corresponds to a first vector obtained by adding a first random number generated by the computer to a zero vector as a component; transmitting, to a terminal, first cryptographic information that represents the first encrypted polynomial; receiving, from a calculation device, second cryptographic information that represents a fourth encrypted polynomial, and receiving, from the calculation device, third cryptographic information that represents a second random number generated by the terminal, the fourth encrypted polynomial including a first operation result that is a result of an operation of a fifth vector and a sixth vector that is obtained by adding, to a second vector, a result of a multiplication of the first random number by the second random number as a component, the first operation result being obtained by calculating from a second encrypted polynomial and a third encrypted polynomial, wherein the second encrypted polynomial is obtained by adding a result of a multiplication of the first encrypted polynomial by the second random number to a second polynomial that corresponds to a third vector obtained by adding zero to the second vector as a component, and the third encrypted polynomial is obtained by encrypting a third polynomial that corresponds to the fifth vector obtained by adding zero to a fourth vector as a component; decrypting the second cryptographic information and the third cryptographic information; and

Assignees

• Fujitsu Ltd

Inventors

• Yasuda Masaya

Classifications

• H04L9/008 Primary

  involving homomorphic encryption · CPC title

• H04L9/3231

  Biological data, e.g. fingerprint, voice or retina (network architectures or network communication protocols for supporting authentication of entities using biometrical features in a packet data network H04L63/0861) · CPC title

• H04L9/14

  using a plurality of keys or algorithms · CPC title

• H04L2209/24

  Key scheduling, i.e. generating round keys or sub-keys for block encryption · CPC title