Algebraic Adversaries in the Universal Composability Framework

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 communi...

Evaluating Security of Voting Schemes in the Universal Composability Framework

In the literature, voting protocols are considered secure if they satisfy requirements such as privacy, accuracy, robustness, etc. It can be time consuming to evaluate a voting protocol with respect to all these requirements and it is not clear that the list of known requirements is complete. Perhaps because of this many papers on electronic voting do not offer any security proof at all. As a s...

Protocol Initialization for the Framework of Universal Composability

Adaptive Universal Composability Framework for Server-Aided Threshold Signature

The threshold signature scheme is a protocol that allows any subset of t parties out of n to generate a signature. Since the t members can cooperate together to compute the secret key, we introduce the server-aided threshold signature, which provides controllability for activating the signing function in a certain enhanced way. In this study, we present a server-aided threshold RSA signature pr...

Lecture 3,4: Universal Composability

3 Proof of the Composition Theorem Let A be any B-limited adversary that interacts with protocol QP in the real-life model. Our goal is to construct a B-limited adversary H that interacts with protocol Q in the f -hybrid model, such that no environment Z can tell the difference between the two interactions. We will construct H via the following three steps. 1. From A we construct an adversary A...