Software Watermarking is the process of transforming a program into a functionally equivalent “marked” program in such a way that it is computationally hard to remove the mark without destroying functionality. Barak, Goldreich, Impagliazzo, Rudich, Sahai, Vadhan and Yang (CRYPTO 2001) defined software watermarking and showed that the existence of indistinguishability obfuscation implies that so...

This dissertation deals with three most important as well as fundamental problems in secure distributed computing, namely Verifiable Secret Sharing (VSS), Byzantine Agreement (BA) and Multiparty Computation (MPC). VSS is a two phase protocol (Sharing and Reconstruction) carried out among n parties in the presence of a centralized adversary who can corrupt up to t parties. Informally, the goal o...

Article history: Received 15 September 2008 Received in revised form 16 February 2009 Accepted 20 April 2009

We propose a cryptosystem that has an inherent key escrow mechanism. This leads us to propose a session based public verifiable key escrow system that greatly improves the amount of key material the escrow servers has to keep in order to decrypt an encryption. In our scheme the servers will only have a single secret sharing, as opposed to a single key from every escrowed player. This is done wh...

A , (m  ) n threshold secret sharing scheme is a method for distributing a secret amongst a group of participants. In a , (m  ) n threshold secret sharing scheme any m participants recover the secret, but no ) 1 (  m participants can [6]. Each of participants is allocated a share of the secret. The secret can only be reconstructed when the shares are combined together [2]. In this paper, we ...

We first explain the notion of secret sharing and also threshold schemes, which can be implemented with the Shamir’s secret sharing. Subsequently, we review social secret sharing [6,10] and its trust function. In a secret sharing scheme, a secret is shared among a group of players who can later recover the secret. We review the construction of a social secret sharing scheme and its application ...

In this paper, we propose a verifiable (t,n)-threshold multi-secret sharing scheme, based on one-dimensional cellular automata where the number of secrets is not restricted by n or t. We show that our scheme can be used to solve an open problem proposed recently in Alvarez et al. (2008) [G. Alvarez, L. Hernández Encinas, A. Martín del Rey, A multisecret sharing scheme for color images based on ...

Distributed key generation (DKG) has been studied extensively in the cryptographic literature. However, it has never been examined outside of the synchronous setting, and the known DKG protocols cannot guarantee safety or liveness over the Internet. In this work, we present the first realistic DKG protocol for use over the Internet. We propose a practical system model for the Internet and defin...