Cryptographic system, cryptographic method, and computer readable medium
AssigneeMitsubishi Electric Corporation
InventorsKatsuyuki Takashima, Yutaka Kawai
Life of this patent
Estimating the term…
Abstract
It is an object to provide predicate encryption that can conceal both attribute information being set in a ciphertext and predicate information being set in a decryption key even in a public key setting. An encryption device 200 generates a ciphertext ctx in which attribute information x is set as a basis vector of a basis D. A conversion device 300 converts with conversion information W the basis D of the ciphertext ctx generated by the encryption device 200 to a basis B so as to generate a ciphertext CTx. A decryption device 400 decrypts the ciphertext CTx generated by the conversion device 300 with a token tkv in which predicate information v is set as a coefficient of a basis vector of a basis B* corresponding to the basis B.
Claims12
A cryptographic system for concealment of both attribute information and predicate information in a search query, the system comprising:
- an encryption device that generates a ciphertext ctx in which attribute information x is set as a coefficient of a basis vector of a basis D;
- a conversion device that converts, using conversion information W, the basis D of the ciphertext ctx generated by the encryption device to a basis B so as to generate a ciphertext CTx;
- and
- a decryption device that decrypts the ciphertext CTx generated by the conversion device with a token tkv in which predicate information v is set as a coefficient of a basis vector of a basis B* corresponding to the basis B, determines whether or not the ciphertext condition which is set in the token tkv based on the decryption of the ciphertext CTx, and outputs result of the query based on the determination.
A cryptographic method for concealment of both attribute information and predicate information in a query, the method comprising:
- generating a ciphertext ctx in which attribute information x is set as a coefficient of a basis vector of a basis D, by an encryption device;
- converting, using conversion information W, the basis D of the generated ciphertext ctx to a basis B so as to generate a ciphertext CTx, by a conversion device;
- decrypting the generated ciphertext CTx, with a token tkv in which predicate information v is set as a coefficient of a basis vector of a basis B* corresponding to the basis B, by a decryption device;
- determining whether or not the ciphertext ctx satisfies a condition which is set in the token tkv based on the decryption of the ciphertext CTx;
- and
- outputting a result of the query based on the determination.
A non-transitory computer readable medium, having stored there on a cryptographic program that when executed causes a computer to
- generate a ciphertext ctx in which attribute information x is set as a coefficient of a basis vector of a basis D;
- convert, using conversion information W the basis D of the generated ciphertext ctx to a basis B so as to generate a ciphertext CTx;
- decrypting the generated ciphertext CTx with a token tkv in which predicate information v is set as a coefficient of a basis vector of a basis B* corresponding to the basis B,
- determining whether or not the ciphertext ctx satisfies a condition which is set in the token tkv based on the decryption of the ciphertext CTx;
- and
- outputting a result of the query based on the determination.
Dependencies are inferred from the claim text.