Cryptographic processing system, key generation device, encryption device, decryption device, key delegation device, cryptographic processing method, and cryptographic processing program

Abstract

Hierarchical predicate encryption (HPE) for inner products with enhanced efficiency of operations. A cryptographic processing system includes a key generation device, an encryption device, and a decryption device. The key generation device generates, as a decryption key sk, a vector in which predicate information v{right arrow over ( )}is embedded in a basis vector of a basis B*for each integer t of t=1, . . . , L. The encryption device generates, as a ciphertext ct, a vector in which attribute information x{right arrow over ( )}is embedded in a basis vector of a basis Bfor at least some integer t of t=1, . . . , L. The decryption device performs a pairing operation on the decryption key skgenerated by the key generation device and the ciphertext ct generated by the encryption device, and decrypts the ciphertext ct.