The use of randomness is prevalent in computer science, from achieving efficient algorithms to ensuring the security of cryptographic systems. This project studied the fundamental questions of the power and limitations of randomness (such as coin flips) in computation. Especially, a major goal is to understand the form of randomness which has enough quality to be used reliably in the extremely wide computing applications.
The major tool in studying the above question is randomness extractor, which is an algorithm that converts low quality random sources into very high quality random bits. This project has vastly advanced our knowledge of randomness extractors. Specifically, significant progress has been achieved towards long standing major open problems, resulting in near optimal constructions of randomness extractors for independent weak random sources, a model that has been studied for over 30 years since the beginning of this area. The project has also led to new and improved extractors for more general models beyond independent sources, such as random sources that are generated with limited resources, sources with limited dependence, and sources arising from bounded collusion leakage.
Another important outcome from this project is the significantly improved understanding of using randomness to achieve security. In this line, the project has led to vastly improved and near optimal constructions of privacy amplification protocols, solving a major open problem of 25 years; and non malleable error correcting codes which can handle a much broader class of attacks that can tamper with the entire codeword. The privacy amplification protocols are widely used in symmetric key cryptography, such as quantum key distribution; the non malleable codes provide extraordinary security protection for data storage.
A third major outcome falls in the direction of constructing error correcting codes for edit errors, which include insertions and deletions and happen frequently in practice. Such errors generalize standard symbol modifications and have been studied for decades since the beginning of information theory, yet without much progress on their corresponding codes. The project has led to substantial progress that achieved near optimal parameters in several different settings. This for the first time brings our understanding of codes for edit errors close to our understanding of codes for standard symbol modifications.
The results from this project have been summarized in more than 15 peer reviewed scientific papers, appearing in top theoretical computer science conferences such as Annual Symposium on Foundations of Computer Science (FOCS), Annual ACM Symposium on the Theory of Computing (STOC), ACM-SIAM Symposium on Discrete Algorithms (SODA), International Colloquium on Automata, Languages and Programming (ICALP) and International Cryptology Conference (Crypto).
Several results from this project have been integrated into the PI's classes, and disseminated through workshops and seminars. The project has supported three PhD students, all of whom have produced high quality research papers that have been published or are under review in top theoretical computer science conferences. The students have also had opportunities to give presentations at conferences and workshops, as well as giving lectures in the PI's classes. One student has graduated and obtained a tenure track assistant professor position in academia, with the other two on the right track towards their degrees.
Last Modified: 08/31/2020
Modified by: Xin Li