New Conditional Privacy-preserving Encryption Schemes in Communication Network

Nowadays the communication networks have acted as nearly the most important fundamental infrastructure in our human society. The basic service provided by the communication networks are like that provided by the ubiquitous public utilities. For example, the cable television network provides the distribution of information to its subscribers, which is much like the water or gas supply systems which distribute the commodities to citizens. The communication network also facilitates the development of many network-based applications such as industrial pipeline controlling in the industrial network, voice over long-term evolution (VoLTE) in the mobile network and mixture reality (MR) in the computer network, etc. Since the communication network plays such a vital role in almost every aspect of our life, undoubtedly, the information transmitted over it should be guarded properly. Roughly, such information can be categorized into either the communicated message or the sensitive information related to the users. Since we already got cryptographical tools, such as encryption schemes, to ensure the confidentiality of communicated messages, it is the sensitive personal information which should be paid special attentions to. Moreover, for the benefit of reducing the network burden in some instances, it may require that only communication information among legitimated users, such as streaming media service subscribers, can be stored and then relayed in the network. In this case, the network should be empowered with the capability to verify whether the transmitted message is exchanged between legitimated users without leaking the privacy of those users. Meanwhile, the intended receiver of a transmitted message should be able to identify the exact message sender for future communication. In order to cater to those requirements, we re-define a notion named conditional user privacy preservation. In this thesis, we investigate the problem how to preserve user conditional privacy in pubic key encryption schemes, which are used to secure the transmitted information in the communication networks. In fact, even the term conditional privacy preservation has appeared in existing works before, there still have great differences between our conditional privacy preservation definition and the one proposed before. For example, in our definition, we do not need a trusted third party (TTP) to help tracing the sender of a message. Besides, the verification of a given encrypted message can be done without any secret. In this thesis, we also introduce more desirable features to our redefined notion user conditional privacy preservation. In our second work, we consider not only the conditional privacy of the message sender but also that of the intended message receiver. This work presents a new encryption scheme which can be implemented in communication networks where there exists a blacklist containing a list of blocked communication channels, and each of them is established by a pair of sender and receiver. With this encryption scheme, a verifier can confirm whether one ciphertext is belonging to a legitimated communication channel without knowing the exact sender and receiver of that ciphertext. With our two previous works, for a given ciphertext, we ensure that no one except its intended receiver can identify the sender. However, the receiver of one message may behave dishonest when it tries to retrieve the real message sender, which incurs the problem that the receiver of a message might manipulate the origin of the message successfully for its own benefit. To tackle this problem, we present a novel encryption scheme in our third work. Apart from preserving user conditional privacy, this work also enforces the receiver to give a publicly verifiable proof so as to convince others that it is honest during the process of identifying the actual message sender. In our forth work, we show our special interest in the access control encryption, or ACE for short, and find this primitive can inherently achieve user conditional privacy preservation to some extent. we present a newly constructed ACE scheme in this work, and our scheme has advantages over existing ACE schemes in two aspects. Firstly, our ACE scheme is more reliable than existing ones since we utilize a distributed sanitizing algorithm and thus avoid the so called single point failure happened in ACE systems with only one sanitizer. Then, since the ciphertext and key size of our scheme is more compact than that of the existing ACE schemes, our scheme enjoys better scalability

Efficient identity based signcryption scheme and solution of key-escrow problem

In cryptography for sending any information from sender to receiver, we have to ensure about the three types of security policies i.e. integrity, confidentiality and authentication. For confidentiality purpose, encryption-decryption technique is used and for authentication purpose digital signature is used, so to ensure this three properties, first sender encrypt the message and then sign the message. Same process done at the receiver end that means first message is decrypted then verified, so it's two step process that increases the communication as well as computation cost. But in many real life applications where more speed and less cost is required like e-commerce applications, we can't use signature then encryption technique, so signcryption is the cryptographic primitives that provides signature as well as encryption at the same time on a single step. First signcryption scheme is proposed by Yullian Zheng in 1997, Since then many signcryption scheme is proposed based on elliptic discrete logarithm problem (ECDLP) , Bilinear pairing, Identity Based and certificateless environment. Many of the Signcryption scheme used Random Oracle Model for their security proofs and few are based on standard model

Identity based cryptography from pairings.

Yuen Tsz Hon.Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.Includes bibliographical references (leaves 109-122).Abstracts in English and Chinese.Abstract --- p.iAcknowledgement --- p.iiiList of Notations --- p.viiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Identity Based Cryptography --- p.3Chapter 1.2 --- Hierarchical Identity Based Cryptosystem --- p.4Chapter 1.3 --- Our contributions --- p.5Chapter 1.4 --- Publications --- p.5Chapter 1.4.1 --- Publications Produced from This Thesis --- p.5Chapter 1.4.2 --- Publications During Author's Study in the Degree --- p.6Chapter 1.5 --- Thesis Organization --- p.6Chapter 2 --- Background --- p.8Chapter 2.1 --- Complexity Theory --- p.8Chapter 2.1.1 --- Order Notation --- p.8Chapter 2.1.2 --- Algorithms and Protocols --- p.9Chapter 2.1.3 --- Relations and Languages --- p.11Chapter 2.2 --- Algebra and Number Theory --- p.12Chapter 2.2.1 --- Groups --- p.12Chapter 2.2.2 --- Elliptic Curve --- p.13Chapter 2.2.3 --- Pairings --- p.14Chapter 2.3 --- Intractability Assumptions --- p.15Chapter 2.4 --- Cryptographic Primitives --- p.18Chapter 2.4.1 --- Public Key Encryption --- p.18Chapter 2.4.2 --- Digital Signature --- p.19Chapter 2.4.3 --- Zero Knowledge --- p.21Chapter 2.5 --- Hash Functions --- p.23Chapter 2.6 --- Random Oracle Model --- p.24Chapter 3 --- Literature Review --- p.26Chapter 3.1 --- Identity Based Signatures --- p.26Chapter 3.2 --- Identity Based Encryption --- p.27Chapter 3.3 --- Identity Based Signcryption --- p.27Chapter 3.4 --- Identity Based Blind Signatures --- p.28Chapter 3.5 --- Identity Based Group Signatures --- p.28Chapter 3.6 --- Hierarchical Identity Based Cryptography --- p.29Chapter 4 --- Blind Identity Based Signcryption --- p.30Chapter 4.1 --- Schnorr's ROS problem --- p.31Chapter 4.2 --- BIBSC and Enhanced IBSC Security Model --- p.32Chapter 4.2.1 --- Enhanced IBSC Security Model --- p.33Chapter 4.2.2 --- BIBSC Security Model --- p.36Chapter 4.3 --- Efficient and Secure BIBSC and IBSC Schemes --- p.38Chapter 4.3.1 --- Efficient and Secure IBSC Scheme --- p.38Chapter 4.3.2 --- The First BIBSC Scheme --- p.43Chapter 4.4 --- Generic Group and Pairing Model --- p.47Chapter 4.5 --- Comparisons --- p.52Chapter 4.5.1 --- Comment for IND-B --- p.52Chapter 4.5.2 --- Comment for IND-C --- p.54Chapter 4.5.3 --- Comment for EU --- p.55Chapter 4.6 --- Additional Functionality of Our Scheme --- p.56Chapter 4.6.1 --- TA Compatibility --- p.56Chapter 4.6.2 --- Forward Secrecy --- p.57Chapter 4.7 --- Chapter Conclusion --- p.57Chapter 5 --- Identity Based Group Signatures --- p.59Chapter 5.1 --- New Intractability Assumption --- p.61Chapter 5.2 --- Security Model --- p.62Chapter 5.2.1 --- Syntax --- p.63Chapter 5.2.2 --- Security Notions --- p.64Chapter 5.3 --- Constructions --- p.68Chapter 5.3.1 --- Generic Construction --- p.68Chapter 5.3.2 --- An Instantiation: IBGS-SDH --- p.69Chapter 5.4 --- Security Theorems --- p.73Chapter 5.5 --- Discussions --- p.81Chapter 5.5.1 --- Other Instantiations --- p.81Chapter 5.5.2 --- Short Ring Signatures --- p.82Chapter 5.6 --- Chapter Conclusion --- p.82Chapter 6 --- Hierarchical IBS without Random Oracles --- p.83Chapter 6.1 --- New Intractability Assumption --- p.87Chapter 6.2 --- Security Model: HIBS and HIBSC --- p.89Chapter 6.2.1 --- HIBS Security Model --- p.89Chapter 6.2.2 --- Hierarchical Identity Based Signcryption (HIBSC) --- p.92Chapter 6.3 --- Efficient Instantiation of HIBS --- p.95Chapter 6.3.1 --- Security Analysis --- p.96Chapter 6.3.2 --- Ordinary Signature from HIBS --- p.101Chapter 6.4 --- Plausibility Arguments for the Intractability of the OrcYW Assumption --- p.102Chapter 6.5 --- Efficient HIBSC without Random Oracles --- p.103Chapter 6.5.1 --- Generic Composition from HIBE and HIBS --- p.104Chapter 6.5.2 --- Concrete Instantiation --- p.105Chapter 6.6 --- Chapter Conclusion --- p.107Chapter 7 --- Conclusion --- p.108Bibliography --- p.10

Generalized ID-based elgamal signatures and extensions

Ankara : The Department of Computer Engineering and the Institute of Engineering and Science of Bilkent University, 2008.Thesis (Master's) -- Bilkent University, 2008.Includes bibliographical references leaves 58-62.ID-based cryptography helps us to simplify key management process in traditional public key infrastructures. Any public information such as the e-mail address, name, etc., can be used as a public key and this solves the problem of obtaining the public key of a party and checking that its certificate is valid. ID-based cryptography has been a very active area of research in cryptography since bilinear pairings were introduced as a cryptographic tool. There have been many proposals for ID-based signatures recently. In this thesis, we introduce the concept of generalized ID-based ElGamal signatures and show that most of the proposed ID-based signature schemes in the literature are special instances of this generalized scheme. We also investigate ID-based signatures providing additional properties. Signature schemes with message recovery provide the feature that the message is recoverable from the signature and hence does not need to be transmitted separately. Blind signatures provide the feature that a user is able to get a signature without giving the actual message to the signer. Finally, signcryption schemes fulfill the job of a digital signature and encryption in a single step with a lower computational cost. We generalize the ID-based signatures providing these properties and obtain numerous new signatures which have not been explored before. The generalized ID-based signatures we described provide a unified framework for ID-based ElGamal signatures and extensions. Additionally, some of our blind signatures turn out to be more efficient than the previously proposed schemes.Kalkan, SaidM.S

Still Wrong Use of Pairings in Cryptography

Several pairing-based cryptographic protocols are recently proposed with a wide variety of new novel applications including the ones in emerging technologies like cloud computing, internet of things (IoT), e-health systems and wearable technologies. There have been however a wide range of incorrect use of these primitives. The paper of Galbraith, Paterson, and Smart (2006) pointed out most of the issues related to the incorrect use of pairing-based cryptography. However, we noticed that some recently proposed applications still do not use these primitives correctly. This leads to unrealizable, insecure or too inefficient designs of pairing-based protocols. We observed that one reason is not being aware of the recent advancements on solving the discrete logarithm problems in some groups. The main purpose of this article is to give an understandable, informative, and the most up-to-date criteria for the correct use of pairing-based cryptography. We thereby deliberately avoid most of the technical details and rather give special emphasis on the importance of the correct use of bilinear maps by realizing secure cryptographic protocols. We list a collection of some recent papers having wrong security assumptions or realizability/efficiency issues. Finally, we give a compact and an up-to-date recipe of the correct use of pairings.Comment: 25 page

A Study on the Secure Online Examination System

13301甲第4475号博士（工学）金沢大学博士論文本文Full 以下に掲載：IJCANDI (International Journal of Computing and Informatics) 1(3) pp.90-100 2016. Universitas Mulawarman & Universiti Malaysia Sabah. 共著者：Abdul Wahid, Masahiro Mamb

Secure Authentication and Privacy-Preserving Techniques in Vehicular Ad-hoc NETworks (VANETs)

In the last decade, there has been growing interest in Vehicular Ad Hoc NETworks (VANETs). Today car manufacturers have already started to equip vehicles with sophisticated sensors that can provide many assistive features such as front collision avoidance, automatic lane tracking, partial autonomous driving, suggestive lane changing, and so on. Such technological advancements are enabling the adoption of VANETs not only to provide safer and more comfortable driving experience but also provide many other useful services to the driver as well as passengers of a vehicle. However, privacy, authentication and secure message dissemination are some of the main issues that need to be thoroughly addressed and solved for the widespread adoption/deployment of VANETs. Given the importance of these issues, researchers have spent a lot of effort in these areas over the last decade. We present an overview of the following issues that arise in VANETs: privacy, authentication, and secure message dissemination. Then we present a comprehensive review of various solutions proposed in the last 10 years which address these issues. Our survey sheds light on some open issues that need to be addressed in the future

A Privacy-Preserving Secure Framework for Electric Vehicles in IoT using Matching Market and Signcryption

The present world of vehicle technology is inclined to develop Electric Vehicles (EVs) with various optimized features. These vehicles need frequent charging which takes a longer time to charge up. Therefore, scheduling of vehicles in charging stations is required. esides, the information of the EVs and its location is also stored by the charging stations and therefore creates a concern of EV privacy. Various researches are going on to solve these problems; however, an efficient privacy-preserving solution is less practiced till date. In this paper, a framework for Electric Vehicle (EV) charging is discussed. The framework uses the concept of Matching Market to identify a charging station and uses the lattice-based cryptography for secure communications. The matching market considers multiple factors to provide the best allocation of charging station and cryptography ensures security and privacy preservation. The use of lattice-based cryptographic hash SWIFFT avoids heavy computation. This usage of matching market and lattice cryptography, more specifically signcryption for EV charging framework are the highlights of the solution and add-ons to the novel features. Overall, the presented framework is efficient in terms of computation and communication cost, satisfaction ratio, slot ratio, charging latency and load balancing index. The performance metrics are compared with recent developments in this field

Lightweight identity based online/offline signature scheme for wireless sensor networks

Data security is one of the issues during data exchange between two sensor nodes in wireless sensor networks (WSN). While information flows across naturally exposed communication channels, cybercriminals may access sensitive information. Multiple traditional reliable encryption methods like RSA encryption-decryption and Diffie–Hellman key exchange face a crisis of computational resources due to limited storage, low computational ability, and insufficient power in lightweight WSNs. The complexity of these security mechanisms reduces the network lifespan, and an online/offline strategy is one way to overcome this problem. This study proposed an improved identity-based online/offline signature scheme using Elliptic Curve Cryptography (ECC) encryption. The lightweight calculations were conducted during the online phase, and in the offline phase, the encryption, point multiplication, and other heavy measures were pre-processed using powerful devices. The proposed scheme uniquely combined the Inverse Collusion Attack Algorithm (CAA) with lightweight ECC to generate secure identitybased signatures. The suggested scheme was analyzed for security and success probability under Random Oracle Model (ROM). The analysis concluded that the generated signatures were immune to even the worst Chosen Message Attack. The most important, resource-effective, and extensively used on-demand function was the verification of the signatures. The low-cost verification algorithm of the scheme saved a significant number of valued resources and increased the overall network’s lifespan. The results for encryption/decryption time, computation difficulty, and key generation time for various data sizes showed the proposed solution was ideal for lightweight devices as it accelerated data transmission speed and consumed the least resources. The hybrid method obtained an average of 66.77% less time consumption and up to 12% lower computational cost than previous schemes like the dynamic IDB-ECC two-factor authentication key exchange protocol, lightweight IBE scheme (IDB-Lite), and Korean certification-based signature standard using the ECC. The proposed scheme had a smaller key size and signature size of 160 bits. Overall, the energy consumption was also reduced to 0.53 mJ for 1312 bits of offline storage. The hybrid framework of identity-based signatures, online/offline phases, ECC, CAA, and low-cost algorithms enhances overall performance by having less complexity, time, and memory consumption. Thus, the proposed hybrid scheme is ideally suited for a lightweight WSN

Post-Quantum Authenticated Encryption against Chosen-Ciphertext Side-Channel Attacks

Over the last years, the side-channel analysis of Post-Quantum Cryptography (PQC) candidates in the NIST standardization initiative has received increased attention. In particular, it has been shown that some post-quantum Key Encapsulation Mechanisms (KEMs) are vulnerable to Chosen-Ciphertext Side-Channel Attacks (CC-SCA). These powerful attacks target the re-encryption step in the Fujisaki-Okamoto (FO) transform, which is commonly used to achieve CCA security in such schemes. To sufficiently protect PQC KEMs on embedded devices against such a powerful CC-SCA, masking at increasingly higher order is required, which induces a considerable overhead. In this work, we propose to use a conceptually simple construction, the ΕtS KEM, that alleviates the impact of CC-SCA. It uses the Encrypt-then-Sign (EtS) paradigm introduced by Zheng at ISW ’97 and further analyzed by An, Dodis and Rabin at EUROCRYPT ’02, and instantiates a postquantum authenticated KEM in the outsider-security model. While the construction is generic, we apply it to the CRYSTALS-Kyber KEM, relying on the CRYSTALSDilithium and Falcon signature schemes. We show that a CC-SCA-protected EtS KEM version of CRYSTALS-Kyber requires less than 10% of the cycles required for the CC-SCA-protected FO-based KEM, at the cost of additional data/communication overhead. We additionally show that the cost of protecting the EtS KEM against fault injection attacks, necessarily due to the added signature verification, remains negligible compared to the large cost of masking the FO transform at higher orders. Lastly, we discuss relevant embedded use cases for our EtS KEM construction