A Fine-Grained Certificateless Conditional Proxy Broadcast Re-Encryption Scheme Without Pairing

Proxy re-encryption allows a semi-trusted proxy to convert the ciphertext of the data owner into the ciphertext of the target user. The certificateless proxy re-encryption eliminates the need for public key certificate in traditional public-key cryptography and key-escrow problem in identity-based cryptography, which makes it more convenient to apply. However, the existing certificateless proxy re-encryption schemes cannot support one-to-many conversion and flexible control on convert conditions. In this paper, we propose a fine-grained certificateless conditional proxy broadcast re-encryption scheme without pairing. In our scheme, the data owner can delegate the decryption rights of the ciphertext that meets certain conditions to the target users, and the data owner can revoke the delegate rights. At the same time, no pairing is used, which makes the scheme more efficient. Finally, we show that the security of the scheme for chosen-ciphertext attacks in the random oracle model