I wish to pursue a Ph.D. in computer science with the ultimate goal of becoming a professor, sharing my knowledge through teaching, and doing research at a university. In the year that I have spent as a teaching assistant I have discovered a strong passion for teaching at a university level. I have thrived in the rich intellectual climate of academia and I want to contribute more actively to it. Because of my strong interests in the field of secure systems, I am compelled to pursue further research in this area.

My interests in Computer and Network security span both cryptography and systems research. I have theorized about electronic voting protocols and built web proxies to collect ephemeral authentication cookies on the web and greatly enjoyed both. Currently I am investigating how people can communicate privately and unobservably, particularly when some large, powerful and unscrupulous adversary is attempting to detect and prevent such communication. Such an adversary could ban standard cryptography, forcing the communication itself to be hidden. In these cases, steganography, the hiding of an encrypted message and its extraction at its destination, becomes extremely relevant. A related concept that I am exploring is covert channels, which are communications channels that violate some security policy.

Having been exposed to the covert channel idea in my reading, I was further inspired to work on this topic by attending the 4th International Information Hiding Workshop. At this workshop I was able to exchange ideas with many people as excited about the subject as I was. Through these interactions I became more aware of the relationships between the fields of steganography, covert channels, watermarking, and anonymous systems, as well as some of the social implications of this work in privacy protection, censorship resistance and intellectual property protection.

The covert channel I am developing is based on embedding encrypted data in the timestamp field for TCP. TCP is a great place to hide information because it is so ubiquitous. Though others before me have identified it as a possible covert channel, these schemes were detectable by an adversary who knew what to look for and their implementations were not complete. By using the timestamp field and careful protocol design, I intend to prevent these shortcomings and make this a secure and usable covert channel. So far, the largest challenge in this project is dealing with reliably sending data over an unreliable channel which only sends one bit of ciphertext per packet. However, we have developed a protocol for this situation which can be generalized to other channels. Presently I am working on this with a group of students as a project for my Computer and Network Security class (6.857), and we have submitted our paper to a conference.

My Master's Thesis project also is related to information hiding and unobservable communication. I am working with Prof. Robert Morris on building a system for steganographically embedding data in a series of images such that it is undetectable and robust against compression. The security of steganography rests on the plausibility of sending the cover medium; plausibility is a fundamentally human concept. One could imagine a perfect steganographic system in which one could embed encrypted data in random data and send it around.

In most cases, however, this solution is not practical since sending random data around is not plausible. To circumvent this limitation, I have designed a system based on embedding data in images. The system chooses images whose hashed values coincide with the data I would like to send. This avoids the risk of modifying images and disturbing their statistical properties. The problem becomes more complex when an active adversary is considered who can make any changes they wish without disturbing the way the images look. Currently I have a working design for my project and am beginning to focus on implementation.

Through researching these issues, I hope to contribute to a generalized theory of steganography and information hiding. I know there is a lot of exploration still to be done in this area and I intend to delve deeper into these issues in my Ph.D. work. Steganography fascinates me because it is such an open field. Though it has been practiced for thousands of years, most of steganography's security has been based on security through obscurity. Not only is there no framework for proving the security of any existing schemes, but also there is no method of determining secure parameters for properties such as the capacity of a channel.

Over the past two terms I have had one of the most rewarding experiences of my life teaching Introduction to Algorithms, 6.046. I have devoted the vast majority of my time to planning recitation sections which present material my students have never seen before, coming up with new problems for problem sets and exams and dealing with students' questions and concerns during office hours. Recently, I taught the dynamic programming paradigm in recitation and it was very heady to see students grasp the concepts I was presenting as the class went on. It is a very exciting experience to teach students of high caliber. They have challenged me with questions which have caused my knowledge of the material to grow immensely. The opportunity to continue to teach is a large part of my motivation to attend graduate school.

I am primarily attracted to graduate study at NYU because of the Secure computer systems group and I hope to have the opportunity to work with Professor Mazieres. I was able to play around with SFS when I built a phase tree file system on top of for 6.894 (Distributed Operating Systems Engineering) and I hope to have more opportunity to do so. I would like to explore unobservable means of publishing documents and broadcasting information using steganography and it would be great to be able to develop these ideas with the people working on Tangler and Publius. I am impressed with how strong the program at NYU is and anticipate that the environment on campus must be truly intellectually stimulating, not to mention that of the great city which surrounds it. NYU is establishing itself as a strong force in my field and I would like to contribute to this synergy.