Proxy re-encryption can achieve decryption permission conversion

while robust threshold proxy re-encryption (TPRE) supports not only secure and flexible conversion control

but also the validity verification of converted ciphertext. An ideal lattices based TPRE was proposed achieving threshold control by Shamir secret sharing and robustness by homomorphic signature technique

which could resist to quantum analysis completely. The new scheme enjoys small ciphertext size

short key share and high calculation speed compared with the similar schemes from standard lattices. Based on the differences between PRE and TPRE security models

attacks on our TPRE can be transformed into corresponding attacks on potential PRE scheme in polynomial time

therefore its security can be reduced to R-LWE (Learning With Errors over Ring) difficult assumption. It provides encryption and cryptographic access control in a decentralized environment

and widely used in scenarios such as file sharing based on blockchain networks and rapid interconnection of multi-domain networks.