Privacy Protection of Social Networks Based on Classified Attribute Encryption

Algorithm 2

File re-encryption.

	Input: access structure tree, new encryption key, ciphertext CT
	Output: CT′
(1)	//Calculate the encrypted , C′.
(2)	= CT · ;
(3)	C′ = ;
(4)	;
(5)	;
(6)	CT′ = {T′, , C, , };