Wu, T. Y., Tseng, Y.M., &Yu, C. W. (2011). A two-tower group key exchange protocol for wireless network environments. EURASIP Journal on Wireless Communications and Networking, 2011 (1), 12 It states that third parties, with the exception of the client and AP, cannot know whether two different protocol sessions are initiated by the same user. In other words, the attacker cannot tell the difference between having seen the same WBANs client twice. Zhao [17] discovered that the protocols of Liu et al. are not secure when the verification table is disclosed. In order to improve security and efficiency, Zhao proposed an effective identity-based anonymous authentication system for WBANs. However, Zhao`s scheme cannot offer real anonymity, because the pseudo-identities of the users have a constant value and the adversary could pull the users; Wang and Zhang then proposed a new anonymous authentication scheme for WBANs [18]. The security analysis shows that the proposed system could overcome the weakness of the previous system. During the registration phase of the proposed schema, the client and server perform mutual authentication on the client`s formula and identity.

As the message is transmitted through a secure channel during the registration phase, only the legitimate customer has the knowledge and calculations. The AP and server are authenticated in the same way to prevent the attacker from constantly sending junk information to AP. In the authentication phase, only the requested AP can authenticate the accessing user by verifying the user`s signature, and AP verifies that the formula is accurate. Among them, the secret value and the hash value are generated. Also, is related to , which can only be restored by AP. The client authenticates AP by the authentication code since it relates to , and the session key is kept secret by the client and the AP. Overall, the proposed scheme provides mutual authentication between the client and AP. Tseng, Y.M(2005).

A robust multi-stakeholder key protocol, resistant to malicious participants. The Computer Journal, 48(4), 480-487. Cao, C., Ma, J., &Moon, p. (2007). Detectable and efficient group key exchange protocol. Wuhan University Journal of Natural Sciences, 12 years old, 41-45. The real identity of the requesting customer cannot be disclosed by third parties, including the application provider [25, 26]. As indicated in paragraph 5, the client sends his pseudonym to the server during the registration phase. The server then sends this pseudonym into a secure channel; Ap then stores as a client identity….