Security Analysis of a Recent Pairing-based Certificateless Authenticated Key Agreement Protocol for Blockchain-based WBANs

In this paper, we proposed some vulnerabilities of a recent pairing-based certificateless authenticated key agreement protocol for blockchain-based wireless body area networks (WBAN). According to our analysis, this protocol is insecure against key offset attack (KOA), basic impersonation attack (BIA), and man-in-the-middle attack (MMA) of the malicious key generation center (KGC) administrators. We also found and pointed out some errors in the description of the protocol

White-box implementation to advantage DRM

Digital Rights Management (DRM) is a popular approach for secure content distribution. Typically, DRM encrypts the content before delivers it. Most DRM applications use secure algorithms to protect content. However, executing these algorithms in an insecure environment may allow adversaries to compromise the system and obtain the key. To withstand such attack, algorithm implementation is modified in such a way to make the implementation unintelligible, namely obfuscation approach. White-box cryptography (WBC) is an obfuscation technique intended to protect secret keys from being disclosed in a software implementation using a fully transparent methodology. This mechanism is appropriate for DRM applications and able to enhance security for the content provider. However, DRM is required to provide a balanced protection for the content provider and users. We construct a protocol on implementing WBC to improve DRM system. The system does not only provide security for the content provider but also preserves privacy for users

CLKS: Certificateless Keyword Search on Encrypted Data

Keyword search on encrypted data enables one to search keyword ciphertexts without compromising keyword security. We further investigate this problem and propose a novel variant, dubbed certificateless keyword search on encrypted data (CLKS). CLKS not only supports keyword search on encrypted data, but also brings promising features due to the certificateless cryptography. In contrast to the certificated-based keyword search, CLKS requires no validation on the trustworthy of the public key before encrypting keywords; in contrast to the identity-based keyword search, CLKS prevents the key issuer (e.g., key generator center) from penetrating any information on keyword ciphertexts by leveraging the capability of accessing all data users’ (partial) private keys. Specifically, we rigorously define the syntax and security definitions for CLKS, and present the construction that is provably secure in the standard model under the Decisional Linear assumption. We implemented the proposed CLKS scheme and evaluated its performance. To the best of our knowledge, this is the first attempt to integrate certificateless cryptography with keyword search on encrypted data

A novel certificateless deniable authentication protocol

Deniable authenticated protocol is a new and attractive protocol compared to the traditional authentication protocol. It allows the appointed receiver to identify the source of a given message, but not to prove the identity of the sender to a third party even if the appointed receiver is willing to reveal its private key. In this paper, we first define a security model for certificateless deniable authentication protocols. Then we propose a non-interactive certificateless deniable authentication protocol, by combining deniable authentication protocol with certificateless cryptography. In addition, we prove its security in the random oracle model

A Multivariate Based Provably Secure Certificateless Signature Scheme with Applications to the Internet of Medical Things

Over the last few years, Internet of Medical Things (IoMT) has completely transformed the healthcare industry. It is bringing out the most notable, and unprecedented impacts on human health, and has totally changed the way we look at the healthcare industry. The healthcare sector all around the globe are leapfrogging, and adopting the technology, helping in transforming drastically in a very short span of time. However, as more and more number of medical devices are being connected to IoMT, security issues like ensuring authenticity and integrity of the transmitted data are also on the rise. In view of the context, there is a need of an efficient cryptographic primitive that can address these issues in a viable manner. A signature scheme seems to be the natural choice to mitigate the security concerns. But, traditional signature schemes, both PKI-based and Identity-based have their own disadvantages which makes them unsuitable for IoMT networks. Thus, to address the security issues and problems like certificate management and key escrow, herein, we put forward the {\em first} multivariate based certificateless signature scheme, namely {\sf Mul-CLS}, which is built on top of the intractability of multivariate-quadratic (MQ) problem. The fact that multivariate public key cryptosystem (MPKC) provides fast, post-quantum safe, and efficient primitives, makes it a front runner candidate among the other post-quantum cryptography candidates. Our scheme {\sf Mul-CLS} provides existential unforgeability against chosen message and chosen identity Super Type I and Super Type II adversary if solving the MQ problem is NP-hard. In addition to that, our proposed {\sf Mul-CLS} presents itself as a robust and cost-friendly cryptographic building block for building IoMT networks

We Can Make Mistakes: Fault-tolerant Forward Private Verifiable Dynamic Searchable Symmetric Encryption

Verifiable Dynamic Searchable Symmetric Encryption (VDSSE) enables users to securely outsource databases (document sets) to cloud servers and perform searches and updates. The verifiability property prevents users from accepting incorrect search results returned by a malicious server. However, we discover that the community currently only focuses on preventing malicious behavior from the server but ignores incorrect updates from the client, which are very likely to happen since there is no record on the client to check. Indeed most existing VDSSE schemes are not sufficient to tolerate incorrect updates from the client. For instance, deleting a nonexistent keyword-identifier pair can break their correctness and soundness. In this paper, we demonstrate the vulnerabilities of a type of existing VDSSE schemes that fail them to ensure correctness and soundness properties on incorrect updates. We propose an efficient fault-tolerant solution that can consider any DSSE scheme as a black-box and make them into a fault-tolerant VDSSE in the malicious model. Forward privacy is an important property of DSSE that prevents the server from linking an update operation to previous search queries. Our approach can also make any forward secure DSSE scheme into a fault-tolerant VDSSE without breaking the forward security guarantee. In this work, we take FAST [1] (TDSC 2020), a forward secure DSSE, as an example, implement a prototype of our solution, and evaluate its performance. Even when compared with the previous fastest forward private construction that does not support fault tolerance, the experiments show that our construction saves 9× client storage and has better search and update efficiency

多人数署名の証明可能安全性に関する研究

筑波大学 (University of Tsukuba)201

Anonymous, authentic, and accountable resource management based on the E-cash paradigm

The prevalence of digital information management in an open network has driven the need to maintain balance between anonymity, authenticity and accountability (AAA). Anonymity allows a principal to hide its identity from strangers before trust relationship is established. Authenticity ensures the correct identity is engaged in the transaction even though it is hidden. Accountability uncovers the hidden identity when misbehavior of the principal is detected. The objective of this research is to develop an AAA management framework for secure resource allocations. Most existing resource management schemes are designed to manage one or two of the AAA attributes. How to provide high strength protection to all attributes is an extremely challenging undertaking. Our study shows that the electronic cash (E-cash) paradigm provides some important knowledge bases for this purpose. Based on Chaum-Pederson’s general transferable E-cash model, we propose a timed-zero-knowledge proof (TZKP) protocol, which greatly reduces storage spaces and communication overheads for resource transfers, without compromising anonymity and accountability. Based on Eng-Okamoto’s general divisible E-cash model, we propose a hypercube-based divisibility framework, which provides a sophisticated and flexible way to partition a chunk of resources, with different trade-offs in anonymity protection and computational costs, when it is integrated with different sub-cube allocation schemes. Based on the E-cash based resource management framework, we propose a privacy preserving service oriented architecture (SOA), which allows the service providers and consumers to exchange services without leaking their sensitive data. Simulation results show that the secure resource management framework is highly practical for missioncritical applications in large scale distributed information systems