Encryption device, encryption method, and information processing device

摘要

An encryption server receives encrypted data which is encrypted by using a public key of a first user and which is added with auxiliary information calculated using a combination of a secret key and the public key of the first user and data to be encrypted. Then, the encryption server generates re-encrypted data obtained by re-encrypting the encrypted data using the auxiliary information added to the encrypted data, a public key of a second user, and encrypted information related to the secret key of the first user which is encrypted with the public key of the second user.

主权项

1. An encryption device comprising:
a reception unit that receives encrypted data which is encrypted by using a public key of a first user and which is added with auxiliary information calculated using data that has not yet been encrypted and a combination of a secret key and the public key of the first user; and a generation unit that generates re-encrypted data obtained by re-encrypting the encrypted data using the auxiliary information added to the encrypted data, a public key of a second user, and encrypted information related to the secret key of the first user which is encrypted with the public key of the second user, wherein the public key and a common key of the first user and the public key and a common key of the second user are generated by a key parameter including a first parameter that represents a lattice dimension, a second parameter that is an arbitrary prime number, and a third parameter that is an arbitrary prime number smaller than the second parameter, and the second parameter corresponding to the second user is a prime number greater than the second parameter corresponding to the first user.