  Cloud-based services have become part of our day-to-day software solutions.
The identity authentication process is considered to be the main gateway to
these services. As such, these gates have become increasingly susceptible to
aggressive attackers, who may use Denial of Service (DoS) attacks to close
these gates permanently. There are a number of authentication protocols that
are strong enough to verify identities and protect traditional networked
applications. However, these authentication protocols may themselves introduce
DoS risks when used in cloud-based applications. This risk introduction is due
to the utilization of a heavy verification process that may consume the cloud
resources and disable the application service. In this work, we propose a novel
cloud-based authentication protocol suite that not only is aware of the
internal DoS threats but is also capable of defending against external DoS
attackers. The proposed solution uses a multilevel adaptive technique to
dictate the efforts of the protocol participants. This technique is capable of
identifying a legitimate users requests and placing them at the front of the
authentication process queue. The authentication process was designed in such a
way that the cloud-based servers become footprint-free and completely aware of
the risks of any DoS attack.
