Fig 1.
The architecture of the work.
Table 1.
The main notations and descriptions.
Fig 2.
System model of the ER-CGKA scheme.
Fig 3.
The main procedure of the ER-CGKA scheme.
Fig 4.
The database (DB) stored on CS.
Fig 5.
The process of ER-CGKA.
Fig 6.
The key agreement for new vehicle joining.
Fig 7.
The key agreement for old vehicle leaving.
Fig 8.
The key agreement for key materials update.
Table 2.
Security comparison.
Table 3.
The comparison of computation cost.
Fig 9.
The run time of client.
Fig 10.
The run time of CS.
Table 4.
The comparison of communication overhead.
Fig 11.
The bandwidth requirements.