Chosen-Ciphertext Secure Fuzzy Identity-Based Key Encapsulation without ROM

We use hybrid encryption with Fuzzy Identity-Based Encryption (Fuzzy-IBE) schemes, and present the first and efficient fuzzy identity-based key encapsulation mechanism (Fuzzy-IB-KEM) schemes which are chosen-ciphertext secure (CCA) without random oracle in the selective-ID model. To achieve these goals, we consider Fuzzy-IBE schemes as consisting of separate key and data encapsulation mechanisms (KEM-DEM), and then give the definition of Fuzzy-IB-KEM. Our main idea is to enhance Sahai and Waters\u27 large universe construction (Sahai and Waters, 2005), chosen-plaintext secure (CPA) Fuzzy-IBE, by adding some redundant information to the ciphertext to make it CCA-secure

Biometric Cryptosystems : Authentication, Encryption and Signature for Biometric Identities

Biometrics have been used for secure identification and authentication for more than two decades since biometric data is unique, non-transferable, unforgettable, and always with us. Recently, biometrics has pervaded other aspects of security applications that can be listed under the topic of ``Biometric Cryptosystems''. Although the security of some of these systems is questionable when they are utilized alone, integration with other technologies such as digital signatures or Identity Based Encryption (IBE) schemes results in cryptographically secure applications of biometrics. It is exactly this field of biometric cryptosystems that we focused in this thesis. In particular, our goal is to design cryptographic protocols for biometrics in the framework of a realistic security model with a security reduction. Our protocols are designed for biometric based encryption, signature and remote authentication. We first analyze the recently introduced biometric remote authentication schemes designed according to the security model of Bringer et al.. In this model, we show that one can improve the database storage cost significantly by designing a new architecture, which is a two-factor authentication protocol. This construction is also secure against the new attacks we present, which disprove the claimed security of remote authentication schemes, in particular the ones requiring a secure sketch. Thus, we introduce a new notion called ``Weak-identity Privacy'' and propose a new construction by combining cancelable biometrics and distributed remote authentication in order to obtain a highly secure biometric authentication system. We continue our research on biometric remote authentication by analyzing the security issues of multi-factor biometric authentication (MFBA). We formally describe the security model for MFBA that captures simultaneous attacks against these systems and define the notion of user privacy, where the goal of the adversary is to impersonate a client to the server. We design a new protocol by combining bipartite biotokens, homomorphic encryption and zero-knowledge proofs and provide a security reduction to achieve user privacy. The main difference of this MFBA protocol is that the server-side computations are performed in the encrypted domain but without requiring a decryption key for the authentication decision of the server. Thus, leakage of the secret key of any system component does not affect the security of the scheme as opposed to the current biometric systems involving cryptographic techniques. We also show that there is a tradeoff between the security level the scheme achieves and the requirement for making the authentication decision without using any secret key. In the second part of the thesis, we delve into biometric-based signature and encryption schemes. We start by designing a new biometric IBS system that is based on the currently most efficient pairing based signature scheme in the literature. We prove the security of our new scheme in the framework of a stronger model compared to existing adversarial models for fuzzy IBS, which basically simulates the leakage of partial secret key components of the challenge identity. In accordance with the novel features of this scheme, we describe a new biometric IBE system called as BIO-IBE. BIO-IBE differs from the current fuzzy systems with its key generation method that not only allows for a larger set of encryption systems to function for biometric identities, but also provides a better accuracy/identification of the users in the system. In this context, BIO-IBE is the first scheme that allows for the use of multi-modal biometrics to avoid collision attacks. Finally, BIO-IBE outperforms the current schemes and for small-universe of attributes, it is secure in the standard model with a better efficiency compared to its counterpart. Another contribution of this thesis is the design of biometric IBE systems without using pairings. In fact, current fuzzy IBE schemes are secure under (stronger) bilinear assumptions and the decryption of each message requires pairing computations almost equal to the number of attributes defining the user. Thus, fuzzy IBE makes error-tolerant encryption possible at the expense of efficiency and security. Hence, we design a completely new construction for biometric IBE based on error-correcting codes, generic conversion schemes and weakly secure anonymous IBE schemes that encrypt a message bit by bit. The resulting scheme is anonymous, highly secure and more efficient compared to pairing-based biometric IBE, especially for the decryption phase. The security of our generic construction is reduced to the security of the anonymous IBE scheme, which is based on the Quadratic Residuosity assumption. The binding of biometric features to the user's identity is achieved similar to BIO-IBE, thus, preserving the advantages of its key generation procedure

Generic Constructions of Biometric Identity Based Encryption Systems

Abstract. In this paper, we present a novel framework for the generic construction of biometric Identity Based Encryption (IBE) schemes, which do not require bilinear pairings and result in more efficient schemes than existing fuzzy IBE systems implemented for biometric identities. Also, we analyze the security properties that are specific to biometric IBE namely anonymity and identity privacy. Considering these notions, we present generic constructions for biometric IBE and ID-KEM based on weakly secure anonymous IBE schemes, error correcting codes and generic conversion schemes. Finally, we describe concrete applications of our framework and compare them to the existing fuzzy IBE systems in terms of time complexity

Dynamic Decentralized Functional Encryption

International audienceWe introduce Dynamic Decentralized Functional Encryption (DDFE), a generalization ofFunctional Encryption which allows multiple users to join the system dynamically, without relying on atrusted third party or on expensive and interactive Multi-Party Computation protocols.This notion subsumes existing multi-user extensions of Functional Encryption, such as Multi-Input, Multi-Client, and Ad Hoc Multi-Input Functional Encryption.We define and construct schemes for various functionalities which serve as building-blocks for latter primitivesand may be useful in their own right, such as a scheme for dynamically computing sums in any Abeliangroup. These constructions build upon simple primitives in a modular way, and have instantiations fromwell-studied assumptions, such as DDH or LWE.Our constructions culminate in an Inner-Product scheme for computing weighted sums on aggregatedencrypted data, from standard assumptions in prime-order groups in the Random Oracle Model

Public-key Authenticated Encryption with Keyword Search: A Generic Construction and Its Quantum-resistant Instantiation

The industrial Internet of Things (IIoT) integrates sensors, instruments, equipment, and industrial applications, enabling traditional industries to automate and intelligently process data. To reduce the cost and demand of required service equipment, IIoT relies on cloud computing to further process and store data. Public-key encryption with keyword search (PEKS) plays an important role, due to its search functionality, to ensure the privacy and confidentiality of the outsourced data and the maintenance of flexibility in the use of the data. Recently, Huang and Li proposed the ``public-key authenticated encryption with keyword search\u27\u27 (PAEKS) to avoid the insider keyword guessing attacks (IKGA) in the previous PEKS schemes. However, all current PAEKS schemes are based on the discrete logarithm assumption and are therefore vulnerable to quantum attacks. In this study, we first introduce a generic PAEKS construction, with the assistance of a trusted authority, that enjoys the security against IKGA in the standard model, if all building blocks are secure under standard model. Based on the framework, we further propose a novel instantiation of quantum-resistant PAEKS that is based on NTRU assumption under random oracle. Compared with its state-of-the-art counterparts, the experiment result indicates that our instantiation is more efficient and secure

Attribute-based group key establishment

Motivated by the problem of establishing a session key among parties based on the possession of certain credentials only, we discuss a notion of attribute-based key establishment. A number of new issues arise in this setting that are not present in the usual settings of group key establishment where unique user identities are assumed to be publicly available. After detailing the security model, we give a two-round solution in the random oracle model. As main technical tool we introduce a notion of attribute-based signcryption, which may be of independent interest. We show that the type of signcryption needed can be realized through the encrypt-then-sign paradigm. Further, we discuss additional guarantees of the proposed protocol, that can be interpreted in terms of deniability and privacy

Towards compact bandwidth and efficient privacy-preserving computation

In traditional cryptographic applications, cryptographic mechanisms are employed to ensure the security and integrity of communication or storage. In these scenarios, the primary threat is usually an external adversary trying to intercept or tamper with the communication between two parties. On the other hand, in the context of privacy-preserving computation or secure computation, the cryptographic techniques are developed with a different goal in mind: to protect the privacy of the participants involved in a computation from each other. Specifically, privacy-preserving computation allows multiple parties to jointly compute a function without revealing their inputs and it has numerous applications in various fields, including finance, healthcare, and data analysis. It allows for collaboration and data sharing without compromising the privacy of sensitive data, which is becoming increasingly important in today's digital age. While privacy-preserving computation has gained significant attention in recent times due to its strong security and numerous potential applications, its efficiency remains its Achilles' heel. Privacy-preserving protocols require significantly higher computational overhead and bandwidth when compared to baseline (i.e., insecure) protocols. Therefore, finding ways to minimize the overhead, whether it be in terms of computation or communication, asymptotically or concretely, while maintaining security in a reasonable manner remains an exciting problem to work on. This thesis is centred around enhancing efficiency and reducing the costs of communication and computation for commonly used privacy-preserving primitives, including private set intersection, oblivious transfer, and stealth signatures. Our primary focus is on optimizing the performance of these primitives.Im Gegensatz zu traditionellen kryptografischen Aufgaben, bei denen Kryptografie verwendet wird, um die Sicherheit und Integrität von Kommunikation oder Speicherung zu gewährleisten und der Gegner typischerweise ein Außenstehender ist, der versucht, die Kommunikation zwischen Sender und Empfänger abzuhören, ist die Kryptografie, die in der datenschutzbewahrenden Berechnung (oder sicheren Berechnung) verwendet wird, darauf ausgelegt, die Privatsphäre der Teilnehmer voreinander zu schützen. Insbesondere ermöglicht die datenschutzbewahrende Berechnung es mehreren Parteien, gemeinsam eine Funktion zu berechnen, ohne ihre Eingaben zu offenbaren. Sie findet zahlreiche Anwendungen in verschiedenen Bereichen, einschließlich Finanzen, Gesundheitswesen und Datenanalyse. Sie ermöglicht eine Zusammenarbeit und Datenaustausch, ohne die Privatsphäre sensibler Daten zu kompromittieren, was in der heutigen digitalen Ära immer wichtiger wird. Obwohl datenschutzbewahrende Berechnung aufgrund ihrer starken Sicherheit und zahlreichen potenziellen Anwendungen in jüngster Zeit erhebliche Aufmerksamkeit erregt hat, bleibt ihre Effizienz ihre Achillesferse. Datenschutzbewahrende Protokolle erfordern deutlich höhere Rechenkosten und Kommunikationsbandbreite im Vergleich zu Baseline-Protokollen (d.h. unsicheren Protokollen). Daher bleibt es eine spannende Aufgabe, Möglichkeiten zu finden, um den Overhead zu minimieren (sei es in Bezug auf Rechen- oder Kommunikationsleistung, asymptotisch oder konkret), während die Sicherheit auf eine angemessene Weise gewährleistet bleibt. Diese Arbeit konzentriert sich auf die Verbesserung der Effizienz und Reduzierung der Kosten für Kommunikation und Berechnung für gängige datenschutzbewahrende Primitiven, einschließlich private Schnittmenge, vergesslicher Transfer und Stealth-Signaturen. Unser Hauptaugenmerk liegt auf der Optimierung der Leistung dieser Primitiven

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

Post-Quantum Era Privacy Protection for Intelligent Infrastructures

As we move into a new decade, the global world of Intelligent Infrastructure (II) services integrated into the Internet of Things (IoT) are at the forefront of technological advancements. With billions of connected devices spanning continents through interconnected networks, security and privacy protection techniques for the emerging II services become a paramount concern. In this paper, an up-to-date privacy method mapping and relevant use cases are surveyed for II services. Particularly, we emphasize on post-quantum cryptography techniques that may (or must when quantum computers become a reality) be used in the future through concrete products, pilots, and projects. The topics presented in this paper are of utmost importance as (1) several recent regulations such as Europe's General Data Protection Regulation (GDPR) have given privacy a significant place in digital society, and (2) the increase of IoT/II applications and digital services with growing data collection capabilities are introducing new threats and risks on citizens' privacy. This in-depth survey begins with an overview of security and privacy threats in IoT/IIs. Next, we summarize some selected Privacy-Enhancing Technologies (PETs) suitable for privacy-concerned II services, and then map recent PET schemes based on post-quantum cryptographic primitives which are capable of withstanding quantum computing attacks. This paper also overviews how PETs can be deployed in practical use cases in the scope of IoT/IIs, and maps some current projects, pilots, and products that deal with PETs. A practical case study on the Internet of Vehicles (IoV) is presented to demonstrate how PETs can be applied in reality. Finally, we discuss the main challenges with respect to current PETs and highlight some future directions for developing their post-quantum counterparts