ENCRYPTION SYSTEM, RE-ENCRYPTION KEY GENERATION DEVICE, RE-ENCRYPTION DEVICE, ENCRYPTION METHOD AND ENCRYPTION PROGRAM

摘要

It is an object to implement a functional proxy re-encryption scheme. A decryption device 300 transmits to a re-encryption device 400 a decryption key k *rk which is generated by converting, using conversion information W 1 , a decryption key k * in which is set one of attribute information x and attribute information v corresponding to each other, and encrypted conversion information È rk which is generated by encrypting the conversion information W 1 with one of attribute information x' and attribute information v' corresponding to each other being set. The re-encryption device 400 generates a re-encrypted ciphertext CT, constituted by a ciphertext c renc which is generated by setting at least one of additional information H and additional information ˜ corresponding to each other in a ciphertext c enc in which is set the other one of the attribute information x and the attribute information v, and a decryption key k *renc which is generated by setting at least the other one of the additional information H and the additional information ˜ in the decryption key k *rk .