Fuzzy Identity-Based Threshold Key-Insulated Encryption with Ciphertext Policy

To solve the signing key exposure problem in fuzzy identity-based encryption systems with ciphertext policy, we propose a fuzzy identity-based threshold key-insulated encryption scheme with ciphertext policy (FIBTKIE-CP) which is provably secure. Our scheme is key-insulated and strongly key-insulated. Even if temporary private keys for up to N-1 time periods are compromised, an adversary is still unable to obtain this user's temporary private key from the remaining time period. Even if up to k -1 helpers are exposed and all temporary private keys are compromised, the adversary still can not harm the security of the non-exposed periods..