An ID-Based Certified E-mail Protocol Suitable for Wireless Mobile Environments

Certified e-mail protocol is a fair exchange of a message for a receipt between two potentially mistrusting parties over the network. A number of certified e-mail protocols have been studied in recent years. However, most of those protocols employ certificate-based cryptography and full trusted third party, which may not be suitable for wireless networks with limited resources such as power, computation and bandwidth. In this work, we propose an improved identity-based (or ID-based) signcryption & re-encryption scheme. Based on this scheme, we develop a novel certified e-mail protocol in the ID-based settings that employ an off-line semi-trusted third party (STTP) for wireless networks. By avoiding the complicated computation from the public key authentication in the certificate-based cryptography, the proposed scheme can simplify the management of the certification process and reduce communication cost in the system. Our detailed elaboration and analysis shows that the proposed approach is dynamic, lightweight and scalable.