Identity Based Proxy Re-encryption Based on a Variant of BB1 Identity Based Encryption

In 1998, Blaze, Bleumer, and Strauss proposed a kind of cryptographic primitive called proxy re-encryption. In proxy re-encryption, a proxy can transform a ciphertext computed under Alice's public key into one that can be opened under Bob's decryption key. In this paper, we pay attention to the role of P KG for proxy re-encryption in identity based setting. We find that if we allow the PKG using its master-key in the process of generating re-encryption key for proxy re-encryption in identity based setting, it is easy to construct an identity based proxy re-encryption scheme based on a variant of BBi identity based encryption (IBE), we also prove its security in the standard model.