Tham khảo tài liệu 'mobile ad hoc networks applications part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 166 Mobile Ad-Hoc Networks Applications Off-line trusted third party models A progress trust negotiation scheme was introduced by Verma Verma et al 2001 . It is a hierarchical trust model where authentication is preformed locally but an off-line trusted third party performs trust management tasks like the issuing of certificates. The off-line trusted third party also manages the certificate revocation process. This scheme is extended through a localized trust management scheme proposed by Davis Davis 2004 . Davis attempts to localize Verma s solution. The only trust management task that is not implemented locally is the issuing of the certificates. Fig. 5. Key Management Solutions a. System Overview Each node possesses its own private key and the trusted third party s public key. The maintenance of these keys is the responsibility of each node. Trust is established when the trustor provides the trustee with a certificate that has not expired or has not been revoked and the trustee can verify it with the trusted third party s public key possessed by the trustee . Furthermore to realize certificate revocation each node must possess two certificate tables a status and profile table. The profile table illustrated in Figure 6 describes the conduct or behaviour of each node. The status table describes the status of the certificate . revoked or valid. These two tables are maintained locally by the nodes themselves with the purpose of maintaining consistent profiles. Trust Establishment in Mobile Ad Hoc Networks Key Management 167 Davis s scheme is a fully distributed scheme. It requires that a node broadcasts its certificates and its profile table to all the nodes in the network. It also requires that each node s profile table be kept updated and distributed with synchronization of data content. The profile table contains information from which the user node may define if a certificate can be trusted or of it must be revoked. Node i s profile table stores three .
