Group-based Proxy Re-encryption Scheme Secure Against Chosen Ciphertext Attack

The notion of proxy cryptography is very useful in cases when one user needs to perform sensitive operation without holding the necessary secret key. Recently, proxy reencryption scheme received much attention due to its application in information storing, secure email, etc. In this paper, we propose a proxy re-encryption used to divert ciphertext from one group to another. The scheme is bidirectional and any member can independently decrypt the ciphertexts encrypted to its group. We discuss the security of the proposed scheme and show that our scheme withstands chosen ciphertext attack in standard model.