Modified Ciphertext-Policy Attribute-Based Encryption Scheme with Efficient Revocation for PHR System

Table 5

Communication overhead of attribute revocation.

	DACC	Yang’s; scheme	Ours; (method 1)	Ours; (method 2)
Update parameters for accessors
Update parameters for cloud storage server

Notes. is the number of ciphertexts which is associated with the revoked attribute . is the number of unrevoked accessors. is the length of each update parameter.