| 摘要 |
An encryption device (200) outputs a ciphertext (ct) including a ciphertext (c) in which one of pieces of attribute information (x, v) is set, and a ciphertext (c~) in which one of pieces of attribute information (y, z) is set. A decryption device (300) outputs a re-encryption key (rk) including a decryption key (k*rk) generated by converting a decryption key (k*) in which the other of the pieces of attribute information (x, v) is set using conversion information (W1, t), a decryption key (k~*rk) in which the other of the pieces of attribute information (y, z) is set, and encryption conversion information (ψrk) in which one of mutually corresponding pieces of attribute information (x', v') is set and the conversion information (W1, t) is encrypted. A re-encryption device (400) outputs a re-ciphertext (rct) including a ciphertext (crenc) generated by setting one of pieces of additional information (H, Θ) in the ciphertext (ct), and a decryption key (k*renc) generated by setting the other of the pieces of additional information (H, Θ) in the re-encryption key (rk). |
