Graduation Year


Document Type




Degree Name

MS in Computer Science (M.S.C.S.)

Degree Granting Department

Engineering Computer Science

Major Professor

Jay Ligatti, Ph.D.

Committee Member

Dmitry Goldgof, Ph.D.

Committee Member

Yao Liu, Ph.D.


Security, access control, authorization


This thesis presents a practical method of authentication utilizing multiple devices. The factors contributing to the practicality of the method are: the utilization of devices already commonly possessed by users and the amenability to being implemented on a wide variety of devices. The term “device” refers to anything able to perform cryptographic operations, store data, and communicate with another such device.

In the method presented herein, multiple devices need to be associated with a single user to provide this user an identity in the system. A public key infrastructure is used to provide this identity. Each of the devices associated with a user possesses a public and private key which allow cryptographic operations to be performed. These operations include signing and encrypting data and will prove the identity of each device. The addition of these identities helps authenticate a single user.

A wide variety of devices qualifies to be used by this authentication method. The minimum requirements are: the storage of data such as a private key, the ability to communicate, and a processor to perform the cryptographic operations. Smart devices possess these requirements and the manufacture of such devices can be realized at a reasonable cost.

This method is malleable and implemented in numerous authentication protocols. This thesis illustrates and explains several instances of these protocols.

The method’s primary novelty is its resistance to theft-based attacks, which results from the utilization of multiple devices to authenticate users. A user associated with multiple devices needs to be in possession of these devices to correctly perform the authentication task. This thesis focuses on the system design of this novel authentication method.