  Cloud-supported Internet of Things (Cloud-IoT) has been broadly deployed in
smart grid systems. The IoT front-ends are responsible for data acquisition and
status supervision, while the substantial amount of data is stored and managed
in the cloud server. Achieving data security and system efficiency in the data
acquisition and transmission process are of great significance and challenging,
because the power grid-related data is sensitive and in huge amount. In this
paper, we present an efficient and secure data acquisition scheme based on
CP-ABE (Ciphertext Policy Attribute Based Encryption). Data acquired from the
terminals will be partitioned into blocks and encrypted with its corresponding
access sub-tree in sequence, thereby the data encryption and data transmission
can be processed in parallel. Furthermore, we protect the information about the
access tree with threshold secret sharing method, which can preserve the data
privacy and integrity from users with the unauthorized sets of attributes. The
formal analysis demonstrates that the proposed scheme can fulfill the security
requirements of the Cloud-supported IoT in smart grid. The numerical analysis
and experimental results indicate that our scheme can effectively reduce the
time cost compared with other popular approaches.
