Table 2.

Comparison of CP-ABE schemes with outsourced verification.

CP-ABE Scheme	Ciphertext Size	Support on Outsourcing Server	Outsourcing Results Verification
Hahn scheme [13]	constant-size ciphertext	Provided	Failed to provide
Wei Teng scheme [14]		Failed to provide
Helil scheme [15]	Proportional to the number of attributes	Provided	Failed to provide
Lai scheme [16]			Verify by inserting the MAC authentication code in the cipher text.
Premkamal scheme [17]			Message verification with VK, which can verify ciphertext.
Qin scheme [18]	constant-size ciphertext		The hash value is used to verify the accuracy of outsourcing decrypt.
Jiguo Li scheme [20]			Verify by inserting the MAC authentication code in the cipher text.
Zhidan Li scheme [21]	Proportional to the number of attributes		After partial decoding on 2 servers, verify that the results match.