This paper explores the critical role of Public Key Infrastructure (PKI) in ensuring the security of electronic transactions, particularly in validating the authenticity of websites in online environments. Traditional Centralised PKIs (CPKIs) relying on Certificate Authorities (CAs) face a significant drawback due to their susceptibility to a single point of failure. To address this concern, Decentralised PKIs (DPKIs) have emerged as an alternative. However, both centralised and decentralised approaches encounter specific challenges. Researchers have made several attempts using blockchain-based PKI, which implements a reward and punishment mechanism to enhance the security of traditional PKI. Most of the attempts are focused on CA-based PKI, which still suffers from the risk of a single point of failure. Inspired by ETHERST, which is a blockchain-based PKI that implements Web of Trust (WoT) with reward and punishment, we introduce ETHERST version 3.0, with improvements in its secure level algorithm that enhances trustworthiness measurement. Comparative simulations between ETHERST version 2.0 and ETHERST version 3.0 reveal the superior performance of the latter in trustworthiness measurement and ensure the higher security of a virtual community. The new simulation algorithm with different node type definitions and assumptions presents results through tables and graphs, showing that ETHERST version 3.0 outperforms ETHERST version 2.0. This research contributes to advancing the field by introducing an innovative PKI solution with enhanced trustworthiness and security features. • Comparison of blockchain-based PKIs which implement reward and punishment mechanism. • Reward and punishment with blockchain-based PKI with an improved new algorithm. • Definition of bad( B ), normal( N ) and good( G ) nodes to improve simulations algorithm.

One of the considerations for the security of searchable symmetric encryption is leakage, defined as the amount of information regarding stored data known to the adversary. Recently, some papers showed that information extracted from leakages, combined with some prior knowledge, enables practical attacks. In this work, we argue in favour on the security of multiserver block-based SSE to resist such attacks, where multiple storage servers are used and the documents are stored in the form of sets of encrypted document blocks. We show that the distribution of documents over keyword subsets in such designs can be used to reduce adversary information gain when conducting such practical attacks on multiserver block-based SSE, therefore offering more resistance to these attacks and achieving higher security guarantees.

ABSTRACT In 2013, Dehkordi and Alimoradi proposed a certificateless identification scheme using supersingular elliptic curves. This proposal came independent of the parallel work of Chin et al. in proposing the first known security models for certificateless identification with provable security. In this paper, we show that there are some design flaws in the Dehkordi–Alimoradi scheme, which lead one to conclude that their scheme is insecure. Copyright © 2014 John Wiley & Sons, Ltd.