New Identity Based Encryption And Its Proxy Re-encryption

Identity based encryption (IBE) has received great attention since Boneh and Franklin’s breakthrough work on bilinear group based IBE [4]. Till now, many IBE schemes relying on bilinear groups with different properties have been proposed [5, 25, 29, 14]. However, one part of the user’s private key in all these IBE schemes is constructed as y = f(msk), where msk is the master key and y is an element in the underlying bilinear group G. In this paper, we propose a new IBE: one part of the private key is y = f(msk), where msk is the master key and y is an element in Z∗ p . Here p is the underlying bilinear group’s prime order. By using some novel techniques, we prove this new IBE is semantic secure under the selective identity chosen plaintext attacks (INDsID-CPA) in the standard model. Based on this IBE scheme, we construct an IND-ID-CCA secure identity based proxy re-encryption (IBPRE) scheme which is master secret secure and efficient for the proxy compared with other IND-ID-CCA (IBPRE) schemes.