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.

The public key encryption with keyword search (PEKS) scheme is a cryptographic primitive introduced to securely store and allow specific searches within encrypted data. Traditional encryption prioritises confidentiality but complicates search operations, requiring decryption before searches can be conducted. PEKS scheme addresses this limitation by enabling authorised users to search for specific keywords within encrypted data without compromising the underlying encryption. This facilitates efficient and secure data retrieval without the need to decrypt the entire dataset. However, PEKS is susceptible to the keyword guessing attack (KGA), exploiting the deterministic nature of the PEKS trapdoor so the adversary can correctly guess the keyword encrypted in a trapdoor. To enhance PEKS security to counter KGA, various schemes have been proposed. A notable one is public key authenticated encryption with keyword search (PAEKS). PAEKS combines authentication and encryption with keyword-bas ed search functionalities, ensuring data source authentication, encrypted information security, and keyword-based searches. This approach offers a more robust and secure alternative to traditional PEKS. However, many existing PAEKS schemes rely on computationally exhaustive bilinear pairing. In this paper, we propose a PAEKS scheme based on k-resilient identity-based encryption without bilinear pairing. By using the provable security approach, we show that our proposed PAEKS scheme satisfies keyword privacy and trapdoor privacy. Furthermore, we also present a performance evaluation of our proposed PAEKS scheme with other related PAEKS schemes and show the efficiency of our proposed scheme.

In this paper, we propose an efficient identity-based identification (IBI) scheme provably secure against impersonation under active and concurrent attacks in the standard model. Based on the proposed IBI scheme and two-tier signature technique, we construct an efficient IBS scheme that is provably secure against strong existential forgery under chosen message attack in the standard model. The security for our proposed IBI and IBS schemes are based on the established q-SDH assumption. The comparison analysis shows that our proposed schemes outperform some state-of-the-art schemes which are also provably secure in the standard model.

Encryption is primarily used to ensure the confidentiality of information transmitted over an insecure wireless channel. However, an encrypted signal may be received with some errors due to noise and interference in the wireless channel. To alleviate these errors in the received encrypted signal, Zibideh and Matalgah proposed two different versions of key‐based coded permutation cipher (KBCPC) aimed to improve the error performance and security of the transmission in the wireless channel. These two versions were designed based on the modified data encryption standard (M‐DES) and provide different levels of security. This study presents a divide‐and‐conquer attack on both M‐DES and KBCPC by exploiting the function that extends the length of output. Their analysis shows that these two ciphers can only provide 56‐bit level of security instead of the claimed 136‐bit and 173.67‐bit level of security for different versions. The authors' analysis is further verified through experiments. More importantly, their attack can be easily adapted to other schemes with a different encryption design but the same coding technique used in M‐DES or KBCPC.

Duan proposed the first certificateless undeniable signature scheme in 2008. Later in 2012, Zhao and Ye proffered an efficient scheme which enjoys from a pairing-free sign algorithm. In this paper, we prove the insecurity of their efficient scheme by mounting two attacks on its invisibility and non-impersonation. In addition, we propose an improved scheme that addresses both of the above attacks while providing better flexibility and additional features for the signer.

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.

ABSTRACT The Galois/Counter Mode of operations (GCM) is constructed by combining the counter mode encryption and the authentication component (i.e., GTAG) to provide both privacy and authenticity. GTAG can be used as a stand‐alone message authentication code. In this paper, we analyze the security of GTAG and GCM with respect to the forgery and distinguishing attacks. More precisely, We generalize the set of weak key classes proposed by Saarinen in FSE 2012 to include all subsets of nonzero keys. Hence, we remove the condition on the smoothness of 2n − 1, where n denotes the block size, for the existence of weak key classes. By considering powers of suitable field elements and linearized polynomials, we further exploit some specific weak key classes to present a universal forgery attack on GTAG. By invoking the birthday paradox arguments, we show that a chosen message attack can be used to distinguish GTAG from a random function. To relax the assumptions required in the universal forgery attack, we show that we can utilize the uniqueness of the counter mode encryption to launch a known ciphertext attack against GCM itself when the initial vector is restricted to 96 bits. The first three attacks can be applied to other Wegman–Carter polynomial message authentication codes. Copyright © 2013 John Wiley & Sons, Ltd.

Message authentication codes (MACs) are widely used in communication networks for authentication purposes. In EUROCRYPT 2002, Black and Rogaway proposed a parallelizable MAC (PMAC), which is relatively efficient when a parallel environment is possible. This parallelism is achieved via constant multiplications in the underlying finite field. In order to yield a better solution, Rogaway refined PMAC in ASIACRYPT 2004 by using a powering-up construction to generate the constants. This is in contrast to the first design that uses successive words of the gray code to generate the constants. In this paper, we analyze how some unique characteristics of these constants result in weaknesses of the respective PMAC designs against forgery attacks in different ways. Thus, our analysis highlights some pitfalls that designers should be mindful of when designing schemes that exploit such constants.

ABSTRACT Fuzzy identity‐based identification (FIBI) scheme is a recently proposed cryptographic identification protocol. The scheme utilizes user biometric trait as public keys. The authentication is deemed success in the presence of the genuine query biometric together with the valid private key. Because of the fuzziness nature of biometrics, FIBI does not correct the errors on the query biometric with respect to the public key; instead, it tolerates the errors using Lagrange polynomial interpolation. Therefore, FIBI requires the biometric trait to be represented in a discrete (binary or integer) array that is fixed in length. In this paper, we report the first realization of FIBI scheme by means of fingerprint biometrics using minutia representation where our technique integrates the security features of both biometric and cryptography effectively. The simulation shows that the entire protocol can be completed within 1 s where false acceptance rate (FAR) = 0% and false reject rate (FRR) = 0.25% in FVC2002 DB1, and FAR = 0% and FRR = 0.125% in FVC2002 DB2. Our integration technique may also be applied on other fuzzy identity‐based cryptosystems. Copyright © 2012 John Wiley & Sons, Ltd.

ABSTRACT On these days, users tend to access to online content via mobile devices, for example, e‐mails. Because these devices have constrained resources, users may wish to instruct e‐mail gateways to search through new e‐mails and only download those corresponding to particular keywords, such as “urgent.” Yet, this searching should not compromise the user's privacy. A public key encryption with keyword search (PEKS) scheme achieves both these requirements. Most PEKS schemes are constructed on the basis of bilinear pairings. Recently, Khader proposed the first PEKS scheme that does not require bilinear pairings and is provably indistinguishable chosen‐keyword attack (IND‐CKA) secure in the standard model. Such a scheme is more efficient than pairing‐based ones. In this paper, we show a drawback of Khader's scheme in that it depends on an unnecessary security assumption: Its IND‐CKA security requires its underlying identity‐based encryption building block to be indistinguishable chosen‐ciphertext attack secure. We construct a more efficient PEKS scheme that achieves the same level of PEKS security as Khader's but that only requires the underlying identity‐based encryption to be indistinguishable chosen‐plaintext attack secure. We give a direct proof that the proposed scheme is IND‐CKA secure. Our scheme outperforms other recent PEKS schemes in literature. Copyright © 2012 John Wiley & Sons, Ltd.

Mobile malware is an increasing threat to the world of handheld devices, which can prove to be costlier than PC viruses in the future. The current method used to combat mobile malware is virus signature matching which is based on the slow process of reverse engineering. This paper studies the growth, spread and generic behaviors of mobile and ubiquitous malware in mobile phones. We extend the works of Bose et al. and Schmidt et al. with an additional feature to reduce the effectiveness of mobile malware propagation. The objective of our work is to investigate the trends and generic behavioral patterns of mobile malware and suggest a generic proof-of-concept model which combines the works of Bose et al. and Schmidt et al. with a new feature to slowdown the spread of known and unknown mobile malware which may share similar behavioral patterns.

In this paper, a new kind of adversarial goal called forge-and-impersonate in undeniable signature schemes is introduced. Note that forgeability does not necessarily imply impersonation ability. The security of the full-domain hash (FDH) variant of Chaum's undeniable signature scheme is then classified according to three dimensions, the goal of adversaries, the attacks, and the zero-knowledge (ZK) level of confirmation and disavowal protocols. Each security is then related to some well-known computational problem. In particular, the security of the FDH variant of Chaum's scheme with noninteractive zero-knowledge (NIZK) protocol confirmation and disavowal protocols is proven to be equivalent to the computational Diffie-Hellman (CDH) problem, as opposed to the gap Diffie-Hellman (GDH) problem as claimed by Okamoto and Pointcheval.

This paper proposes variants of MMH and SQUARE universal hash functions families over the finite field (Galois field) GF (2/sup n/). These new variants are suited for implementation on platforms where there are no built-in specialized algorithms for modular multiplication. There are especially suited on platforms, which have already an embedded GF (2/sup n/)-based cryptosystem. These variants can be utilized to provide efficient and secure message authentication.