Hybrid Proxy Re-encryption Scheme for Attribute-Based Encryption

In ciphertext policy attribute based encryption (ABE) schemes the sender selects an access structure and generates a ciphertext, which decryptors can get plaintext if he has certain set of secret key associate with his attributes which satisfies the access structure. On the other hand, many organisations already introduced standard identity based encryption (TEE) or public key encryption (PKE) where only a single recipient is specified at the time of encryption. To utilize the above schemes and to simplify the management of user's key, it is valuable to develop a proxy re-encryption schemes between ABE schemes and IBE schemes. In this paper we propose the first proxy re-encryption scheme, which can convert an ABE ciphertext to a ciphertext which is encrypted by IBE scheme. Using new proxy re-encryption scheme, some useful applications can he constructed. Furthermore, we prove the security in the standard model based on decisional bilinear Diffie-Hellman assumption.