As a new type of wireless mobile networks, Ad Hoc networks do not depend on any fixed infrastructure, and have no centralized control unit and so its computation capabilities are limited by mobile nodes. In this paper, a novel multi-party key agreement scheme with password authentication and sharing password evolvement for Ad Hoc networks is proposed based on ECC (elliptic curves cryptography). One of the functions of passwords is used as sharing information to authenticate the mobile node's

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... ret keys, and the other is used as a symmetrical key to encrypt alternating information between mobile nodes. The freshness and security of passwords are guaranteed by sharing password evolvement every time in mobile node's secret keys authentication and key agreement. Consequently, the computational overheads and the store load of mobile nodes are lessened, moreover, secret keys authentication and information encryption between mobile nodes are provided. The new scheme enjoys many secure properties such as against man-in-the-middle attack, against replay attack, key independence, forward security, etc.