Anonymous Authentication Protocols For Audio And Video Communication Over Wireless Roaming Networks

With the development and maturity of wirless and mobile communication technology, the large-scale interconnection of heterogeneous networks has been a trend. As the wireless signal is transmitted through the public environment, roaming communication especially audio and video communication across wireless networks faces many problems such as security and performance. Design of authentication and key agreement (AKA) protocol to protect users' privacy when roaming in foreign networks has become an important element of security research, especially user anonymity of audio and video communication across roaming networks. Most existing AKA protocols require user's home server to be involved when user roams to a foreign network, resulting in many message flows, which makes AKA difficult to realize in low-bandwidth wireless networks. Therefore, this study will focus on the design of secure and efficient anonymous authentication protocols without the need for home server in the mobile audio and video communications.Digital signature is the main content of authentication system. It provides the important technology of authentication, integrity and non-repudiation. Special digital signature which fully meets the needs of special purpose is an important research direction. Group signature and proxy signature are two special digital signatures, and ticket is a special-purpose digital signature. They have a very wide range of applications in real life. Due to limited time and space, this paper mainly focused on anonymous authentication protocols based on special signatures, and achieved the following results:1. Based on group signature, four improvements which have better performance than Yang GM protocol are proposed for heterogeneous roaming networks. Although group signature can provide strongly anonymous authentication, it consumes computation of mobile nodes, so four improvements making use of authentication context transfer protocol (ACTP) to simplify the re-authentication process are proposed. The first one uses symmetric encryption to get good performance, but its security is low; the second one uses a message authentication code (MAC) value to maintain high performance as well as moderate security, but without formal design, its formal proof of security remains to be proved; the third one formally designs the protocol based on CK model to improve security, though it imposes more burden on the mobile terminals than the former, it needs less message flows; the last one is formally designed making use of elliptic curve public key cryptography (ECC) to improve performance, so not only its safety is assured, but also its performance is better than the third one.2. Based on proxy signature, three anonymous authentication protocols fit for wireless roaming networks are proposed. One of them is an improvement of an anonymous authentication protocol based on partial delegation, the other two are new protocols based on delegation by warrant. By comparison analysis, the performance of anonymous authentication protocol based on proxy signature is better than that based on group signature, but the anonymity of the former is weaker than that of the latter, so the former is appropriate for environments which the terminal has limited computing power but anonymity intensity is not critical.3. Based on ticket, a practical anonymous authentication protocol for mobile networks is proposed. The protocol has the following advantages: it is formally designed using CK model, so it is secure (SK-secure); the ticket, which can be used repeatedly, is issued without the participation of visited server; the roaming authentication phase does not require the involvement of home server, so fewer rounds of interaction, which means few message flows are needed. Analysis shows that the protocol has high security, user anonymity and efficiency for mobile networks, so it is suitable for large-scale and practical application.