Miller, Daniel2010-06-252010-06-252010-06-252010http://hdl.handle.net/10012/5281Real-time media streams are a common application on the Internet today. For many such streams, it is necessary to provide authentication, data integrity, and non-repudiation. Some applications where this type of security may be necessary include voice-over-IP (VoIP) calls, transmission of sensitive data such as medical records or personal information, or financial data that needs to be updated in real-time. It is important to be able to balance the need for security with the constraints of the environment, where data must be delivered in a limited amount of time. This thesis examines and classifies the different types of authentication based on a number of factors, mainly the type of authentication (user or data), the way in which authentication information is transmitted (embedded or appendix), and the secrecy of the authentication information (covert or overt). This thesis then presents a specific real-time communication system, and develops a novel method of achieving data authentication for the system, based on previous work done in the area of hash-chaining authentication schemes. Theoretical and simulated results are presented, showing that the new method, the modified butterfly scheme, outperforms the original method, the butterfly scheme, using the same amount of overhead.enMaster ThesisElectrical and Computer Engineering