Conditional Traceability Clause Samples

Conditional Traceability. In our scheme, the participants (V , D and CC) choose random numbers α , β , r , r and Game G4: G4 is the final game in which by intercepting the messages ▇▇, ▇▇, ▇▇, ▇▇ tries to compute the session key SKi,j = H7(riRj si,j PIDj Ti,j Tcc) with the help of calculation of the ephemeral secrets riRj, si,j, ▇▇∗ and Ci,j. To derive riRj, it is required to get the ephemeral secrets ri and rj. The ephemeral secrets ri and rj are randomly generated by the vehicle Vi and the drone Dj respectively. Therefore, even if knows ▇▇ and Rj, it is hard to calculate the private key. That is, needs to solve the CDH problem within a short run time t to compute the real session key SKi,j shared between Vi and Dj. Thus, we can get the following relationship: |Pr [SCG4 ] − Pr [SCG3 ]| ≤ AdvA (t). (6) At last, all the oracles are simulated by . The adversary is only left to guess the value of c for winning the game after querying Test(V α, Djβ) query. Thus, Pr[SCG ] has the generates dynamic timestamps Ti, Tj, Tcc, Ti,j to compute temporary ciphertext messages. So cannot trace the behavior of the participants, that is, our scheme could provide un- traceability. Besides, when the vehicle misbehaves, the CC can trace its real identity by analyzing its messages. Only CC can decrypt the real identity IDi of the vehicle by computing [IDi, DIDj, PIDj, Ti] = DR∗ (Ci). Therefore the condi- tional traceability of our proposed scheme is guaranteed.