Graduation Year


Document Type




Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Computer Science and Engineering

Major Professor

Yao Liu, Ph.D.

Committee Member

Jay Ligatti, Ph.D.

Committee Member

Xinming Ou, Ph.D.

Committee Member

Kaiqi Xiong, Ph.D.

Committee Member

Qiong Zhang, Ph.D.


authentication, online services, System security


This dissertation includes three approaches we have been designed to tackle threats and challenges in network, software, and mobile security. The first approach demonstrates a new class of content masking attacks against the Adobe PDF standard, causing documents to appear to humans dissimilar to the underlying content extracted by information-based services. The second work protects sensitive data in binaries from being corrupted by cyber attackers. The last work proposes a mechanism which utilizes the unique walking patterns inherent to humans and differentiate our work from other walking behavior studies by using it as first-order authentication and developing matching methods fast enough to act as an actual anti-theft system.