Cryptanalysis of an Efficient and Secure Certificateless Aggregate Signature-Based Authentication Scheme for Vehicular Ad Hoc Networks

Table 4

Comparison of communication overhead.

Scheme	Single signature length	Aggregate signature length	Coalition attack	Types I and II attacks
Kumar et al. [4]	= 2048 bits	bits	No	Yes
Mei et al. [13]	= 2048 bits	= 2048 bits	No	Yes
Xu et al. [14]	= 2048 bits	bits	No	Yes
Thumbur et al. [18]	= 480 bits	= 320n + 160 bits	No	No
Our scheme	= 480 bits	= 320n + 160 bits	Yes	Yes

Note. n: the number of messages.