Error-Free Message Transmission in the Universal Composability Framework

This thesis introduces models for error-prone communication channels and functionalities for error-free communication in the Universal Composability framework. Realizing these functionalities enables protocols to make use of cryptographic errorcorrecting schemes which are more powerful than classical codes. First, we define new ideal functionalities TrCLOSE and FCWT to model error-prone communication channels. Then, we define four different ideal functionalities for errorfree message transmission, each providing successively stronger message delivery guarantees. Using ideal message certification, we give protocols which realize three of these functionalities for error rates up to 1/2. Finally, we prove that the fourth functionality, which models error-free data storage, is not realizable if the error rate exceeds 1/4. Thesis Supervisor: Ronald L. Rivest Title: Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science Thesis Supervisor: Chris Peikert Title: Thesis Co-Supervisor