[Retracted] A Novel Hierarchical Key Assignment Scheme for Data Access Control in IoT

Table 2

Performance comparison between our scheme and Zhou et al.’s scheme.

Scheme	Private information of each user (besides )	Public information of system	Key derivation in dependent key scheme or obtaining encryption key in independent key scheme	Maximal computation and communication costs for rekeying
Zhou et al.’s scheme [32]				,
Our scheme				,

Notations: : number of classes in the access graph . : number of users in the access graph . : computation cost for decryption of a public key encryption scheme. : computation cost of n-multilinear map. : computation cost of modular exponent. : computation cost of XOR operator. : computation cost of hash function.