Efficient identity based proxy-signcryption schemes with forward security and public verifiability

Li and Chen proposed an identity based proxy-signcryption scheme which is based on the Libert and Quisquater's identity based signcryption scheme recently. However, we demonstrate that their scheme does not satisfy the strong unforgeability and forward security in the strict sense. Furthermore, establishing a secure channel has much influence on their scheme. Based on the new ID-based signcryption scheme proposed by Chow et al, an efficient forward secure and public verifiable identity based proxy-signcryption scheme without the secure channel is proposed. The proposed scheme overcomes the weakness of Li-Chen scheme. The security and performance of the scheme are also analyzed.