A² Chain: A Blockchain-Based Decentralized Authentication Scheme for 5G-Enabled IoT

Table 7

Comparison of time cost cryptographic operations in authentication.

Scheme	User	Server
A^2 Chain	+  + 2 +  + 2  + 2	+  +2 + +2+2
ES^3A [25]	6 + 3 + 3 +	3 + 8 + 4
CPAL [27]	16 + 7	10 + 7
LCCH [54]	30^1 + 8 + 8	23 + 6 + 5
E-AUA [55]	2 +3 +	2 + 2 +

¹ indicates the exponentiation in , and the meanings of other symbols are similar to the above definition.