Verifiable Secret Sharing

Robust threshold digital signature schemes are group signature schemes aiming to depart from the classical one person signer schemes. The term 'robust' means that such schemes can tolerate errors attempted by malicious adversary and the term 'threshold' means that given a total of n players, no coalition of players with cardinality less than or equal the threshold value can perform the signature while any coalition of players exceeding the threshold value can perform the signature correctly. The contributions in this paper are two fold. First, we propose a new verifiable secret sharing scheme (VSS) other than Feldman's (1987) and Pedersen's (1992) schemes suitable to protect elliptic curve secret keys. The proposed scheme utilizes a strong one way function provided by the elliptic curve cryptography based on a different type of group mathematics. Next, we employ the elliptic curve VSS to propose a robust threshold elliptic curve digital signature scheme that can withstand an n/2 eavesdropping, n/3 halting and an n/4 malicious adversary. The scheme is able to tolerate n/3 malicious adversary with the cost of higher complexity

A publicly verifiable secret sharing (PVSS) scheme is a ver- ifiable secret sharing scheme with the property that the validity of the shares distributed by the dealer can be verified by any party; hence veri- fication is not limited to the respective participants receiving the shares. We present a new construction for PVSS schemes, which compared to previous solutions by

Widespread utilization of mobile ad hoc networks (MANETs), which communicate via broadcast wireless channels without any sort of infrastructure, raises security concerns. Introduction of identity-based cryptography (IBC) shed some light to security problems of MANETs. Key management (KM) plays significant role in network security. Although many proposals are suggested for identity based KM, they usually assume a trusted set of nodes during network initialization, which is not the case in many real world applications. In this paper, a novel identity based KM method is proposed which utilizes Pedersen’s verifiable secret sharing method. By distributing shared secret and key generation role among network nodes, proposed method provides high levels of availability and scalability, while eliminating single point of failure. The proposed method provides a mechanism to check the validity of secret shares, which are generated by network nodes. To illustrate the effectiveness and capabilities of proposed methods, they are simulated and compared with the performance of the existing methods.

In this paper, we propose a novel (2,2)(2,2) verifiable secret sharing (VSS) scheme, which not only protects a secret image but also allows users to verify the restored secret image in the revealing and verifying phase, for all binary, grayscale and color images. Error diffusion and image clustering techniques are adopted to achieve our objective. Experimental results and discussions show that the proposed scheme, with its smaller shadow size and lower computational complexity, obviously outperforms previous VSS schemes designed either with or without the cheating prevention mechanism. Moreover, the use of a halftone logo gives an efficient solution to verifying whether the restored secret image is correct by using a halftone logo.

Federated Leaning is an emerging approach to manage cooperation between a group of agents for the solution of Machine Learning tasks, with the goal of improving each agent’s performance without disclosing any data. In this paper we present a novel algorithmic architecture that tackle this problem in the particular case of Anomaly Detection (or classification or rare events), a setting where typical applications often comprise data with sensible information, but where the scarcity of anomalous examples encourages collaboration. We show how Random Forests can be used as a tool for the development of accurate classifiers with an effective insight-sharing mechanism that does not break the data integrity. Moreover, we explain how the new architecture can be readily integrated in a blockchain infrastructure to ensure the verifiable and auditable execution of the algorithm. Furthermore, we discuss how this work may set the basis for a more general approach for the design of federated ensem...

The unique characteristics and constraints of MANET have made the traditional approach to security inadequate. With this view in mind decentralized group key management is taken into consideration. A novel structure of the node is proposed and each entity holds a secret share SS i of each node in cluster is controlled by its cluster head, the policy enforcer decides for the working of intelligent agent, which is assigned to do the management, which allows two or more parties to derive shared key as a function of information associated with the protocol and so no party can predetermine the resulting value. Group membership certificate is used for group authentication and by the use threshold key scheme secret data is transferred. The SS i of each node is calculated by use of Polynomial interpolation and cluster head key by modular arithmetic, and information is carried by the policy based agents named intelligent agents.

The round complexity of interactive protocols is one of their most important complexity measures. In this work we prove that existing lower bounds for the round complexity of VSS can be circumvented by introducing a negligible probability of error in the reconstruction phase. Previous results show matching lower and upper bounds of three rounds for VSS, with n = 3t + 1, where the reconstruction of the secrets always succeeds, i.e. with probability 1. In contrast we show that with a negligible probability of error in the reconstruction phase: There exists an efficient 2-round VSS protocol for n = 3t + 1. If we assume that the adversary is non-rushing then we can achieve a 1-round reconstruction phase. There exists an efficient 1-round VSS for t = 1 and n > 3. We prove that our results are optimal both in resilience and number of sharing rounds by showing: There does not exist a 2-round WSS (and hence VSS) for n ≤ 3t. There does not exist a 1-round VSS protocol for t ≥ 2 and n ≥ 4.