Smart grid puts forward high requirements for the equipment to access authentication, which achieves openness and real-time performance in mart grid. The users’ identities need to protect, in the meanwhile, identity authentication and data encryption should be efficient. According to the characteristics of smart grid, this paper proposed an identity-based aggregation signcryption scheme which combined pseudonymous ID with batch verification. The scheme adopted the pseudonym technology to achieve the user identity anonymity, and adopted the signcryption to complete digital signature and encryption in one time. This paper presented the aggregation signcryption for different multiple users by dynamic equation, which can compromise the security and computation overhead to meet the requirements of smart grid. This scheme can reduce the computational burden of aggregators with security of communication data. Moreover, this scheme solved the difficult problem of the management of pseudonymous ID, and improved the efficiency of the whole system. Therefore, this scheme meets the requirement of real time and high efficiency in smart grid.

Combined electric vehicles with smart grid, Vehicle-to-Grid (V2G) resolve the problem of charging large-scale electric vehicles, and make vehicles as mobile and distributed storage unit accessing to smart grid. V2G requires more efficient authentication protocol to meet fast response and information processing in real-time. Batch authentication can provide large computational savings when several signatures are verified together, which is appropriate for aggregators to verify PHEVs/PEVs. This paper proposes a modified batch authentication protocol based on hybrid cryptography, which takes advantage of public key cryptology to identity authentication and transmit shared session key. Furthermore, the comparison and analysis of the modified with existing batch authentication in V2G are given.