Leakage-resilient Identity-based Encryption in Bounded Retrieval Model with Nearly Optimal Leakage-Ratio

We propose new constructions of leakage-resilient public-key encryption (PKE) and identity-based encryption (IBE) schemes in the bounded retrieval model (BRM). In the BRM, adversaries are allowed to obtain at most $\ell$-bit leakage from a secret key and we can increase $\ell$ only by increasing the size of secret keys without losing efficiency in any other performance measure. We call $\ell/|\textsf{sk}|$ leakage-ratio where $|\textsf{sk}|$ denotes a bit-length of a secret key. Several PKE/IBE schemes in the BRM are known. However, none of these constructions achieve a constant leakage-ratio under a standard assumption in the standard model. Our PKE/IBE schemes are the first schemes in the BRM that achieve leakage-ratio $1-\epsilon$ for any constant $\epsilon>0$ under standard assumptions in the standard model. As previous works, we use identity-based hash proof systems (IB-HPS) to construct IBE schemes in the BRM. It is known that a parameter for IB-HPS called the universality-ratio is translated into the leakage-ratio of the resulting IBE scheme in the BRM. We construct an IB-HPS with universality-ratio $1-\epsilon$ for any constant $\epsilon>0$ based on any inner-product predicate encryption (IPE) scheme with compact secret keys. Such IPE schemes exist under the $d$-linear, subgroup decision, learning with errors, or computational bilinear Diffie-Hellman assumptions. As a result, we obtain IBE schemes in the BRM with leakage-ratio $1-\epsilon$ under any of these assumptions. Our PKE schemes are immediately obtained from our IBE schemes

Practical Predicate Encryption for Inner Product

Inner product encryption is a powerful cryptographic primitive, where a private key and a ciphertext are both associated with a predicate vector and an attribute vector, respectively. A successful decryption requires the inner product of the predicate vector and the attribute vector to be zero. Most of the existing inner product encryption schemes suffer either long private key or heavy decryption cost. In this manuscript, an efficient inner product encryption is proposed. The length for a private key is only an element in $\mathbb{G}$ and an element in $\mathbb{Z}_p$. Besides, only one pairing computation is needed for decryption. Moreover, both formal security proof and implementation result are demonstrated in this manuscript. To the best of our knowledge, our scheme is the most efficient one in terms of the private key length and the number of pairings computation for decryption

Leakage-Resilient IBE/ABE with Optimal Leakage Rates from Lattices

We derive the first adaptively secure IBE and ABE for t-CNF, and selectively secure ABE for general circuits from lattices, with $1-o(1)$ leakage rates, in the both relative leakage model and bounded retrieval model (BRM). To achieve this, we first identify a new fine-grained security notion for ABE -- partially adaptive/selective security, and instantiate this notion from LWE. Then, by using this notion, we design a new key compressing mechanism for identity-based/attributed-based weak hash proof system (IB/AB-wHPS) for various policy classes, achieving (1) succinct secret keys and (2) adaptive/selective security matching the existing non-leakage resilient lattice-based designs. Using the existing connection between weak hash proof system and leakage resilient encryption, the succinct-key IB/AB-wHPS can yield the desired leakage resilient IBE/ABE schemes with the optimal leakage rates in the relative leakage model. Finally, by further improving the prior analysis of the compatible locally computable extractors, we can achieve the optimal leakage rates in the BRM

Efficient privacy preserving predicate encryption with fine-grained searchable capability for cloud storage

With the fast development in Cloud storage technologies and ever increasing use of Cloud data centres, data privacy and confidentiality has become a must. Indeed, Cloud data centres store each time more sensitive data such as personal data, organizational and enterprise data, transactional data, etc. However, achieving confidentiality with flexible searchable capability is a challenging issue. In this article, we show how to construct an efficient predicate encryption with fine-grained searchable capability. Predicate Encryption (PEPE) can achieve more sophisticated and flexible functionality compared with traditional public key encryption. We propose an efficient predicate encryption scheme by utilizing the dual system encryption technique, which can also be proved to be IND-AH-CPA (indistinguishable under chosen plain-text attack for attribute-hiding) secure without random oracle. We also carefully analyse the relationship between predicate encryption and searchable encryption. To that end, we introduce a new notion of Public-Key Encryption with Fine-grained Keyword Search (PEFKSPEFKS). Our results show that an IND-AH-CPA secure PE scheme can be used to construct an IND-PEFKS-CPA (indistinguishable under chosen plain-text attack for public-key encryption with fine-grained keyword search) secure PEFKSPEFKS scheme. A new transformation of PE-to-PEFKS is also proposed and used to construct an efficient PEFKSPEFKS scheme based on the transformation from the proposed PEPE scheme. Finally, we design a new framework for supporting privacy preserving predicate encryption with fine-grained searchable capability for Cloud storage. Compared to most prominent frameworks, our framework satisfies more features altogether and can serve as a basis for developing such frameworks for Cloud data centres.Peer ReviewedPostprint (author's final draft

Generic Construction of Forward Secure Public Key Authenticated Encryption with Keyword Search

Forward security is a fundamental requirement in searchable encryption, where a newly generated ciphertext is not allowed to be searched by previously generated trapdoors. However, forward security is somewhat overlooked in the public key encryption with keyword search (PEKS) context and there are few proposals, whereas forward security has been stated as a default security notion in the (dynamic) symmetric searchable encryption (SSE) context. In the PEKS context, forward secure PEKS (FS-PEKS) is essentially the same as public key encryption with temporary keyword search (PETKS) proposed by Abdalla et al. (JoC 2016) which can be constructed generically from hierarchical identity-based encryption (HIBE) with level-1 anonymity. Alternatively, Zeng et al. (IEEE Transactions on Cloud Computing 2022) also proposed a generic construction of FS-PEKS from attribute-based searchable encryption supporting OR gates. In the public key authenticated encryption with keyword search (PAEKS) context, a concrete forward secure PAEKS (FS-PAEKS) construction has been proposed by Jiang et al. (The Computer Journal 2022). As an independent work, thought Xu et al. proposed a generic construction of FS-PAEKS (ePrint 2023), they employed the Liu et al. generic construction of PAEKS (AsiaCCS 2022) that requires random oracles. Thus, a generic construction of FS-PAEKS without random oracles has not been proposed so far. In this paper, we propose a generic construction of FS-PAEKS from PAEKS. In addition to PAEKS, we employ 0/1 encodings proposed by Lin et al. (ACNS 2005). We also show that the Jiang et al. FS-PAEKS scheme does not provide forward security, and thus our generic construction yields the first secure FS-PAEKS schemes. Our generic construction is quite simple, and it can also be applied to construct FS-PEKS. Our generic construction yields a comparably efficient FS-PEKS scheme compared to the previous scheme. Moreover, it eliminates the hierarchical structure or attribute-based feature of the previous generic constructions which is meaningful from a feasibility perspective

Application and Theory of Multimedia Signal Processing Using Machine Learning or Advanced Methods

This Special Issue is a book composed by collecting documents published through peer review on the research of various advanced technologies related to applications and theories of signal processing for multimedia systems using ML or advanced methods. Multimedia signals include image, video, audio, character recognition and optimization of communication channels for networks. The specific contents included in this book are data hiding, encryption, object detection, image classification, and character recognition. Academics and colleagues who are interested in these topics will find it interesting to read

Advances in Information Security and Privacy

With the recent pandemic emergency, many people are spending their days in smart working and have increased their use of digital resources for both work and entertainment. The result is that the amount of digital information handled online is dramatically increased, and we can observe a significant increase in the number of attacks, breaches, and hacks. This Special Issue aims to establish the state of the art in protecting information by mitigating information risks. This objective is reached by presenting both surveys on specific topics and original approaches and solutions to specific problems. In total, 16 papers have been published in this Special Issue

Advances in Functional Encryption

Functional encryption is a novel paradigm for public-key encryption that enables both fine-grained access control and selective computation on encrypted data, as is necessary to protect big, complex data in the cloud. In this thesis, I provide a brief introduction to functional encryption, and an overview of my contributions to the area

Title list of documents made publicly available. Volume 17, No. 1

This document is a monthly publication containing descriptions of information received and generated by the US Nuclear Regulatory Commission (NRC). This information includes (1) docketed material associated with civilian nuclear power plants and other uses of radioactive materials, and (2) nondocketed material received and generated by NRC pertinent to its role as a regulatory agency. The following indexes are included: Personal author, corporate source, report number, and cross reference of enclosures to principal documents

African Handbook of Climate Change Adaptation

This open access book discusses current thinking and presents the main issues and challenges associated with climate change in Africa. It introduces evidences from studies and projects which show how climate change adaptation is being - and may continue to be successfully implemented in African countries. Thanks to its scope and wide range of themes surrounding climate change, the ambition is that this book will be a lead publication on the topic, which may be regularly updated and hence capture further works. Climate change is a major global challenge. However, some geographical regions are more severly affected than others. One of these regions is the African continent. Due to a combination of unfavourable socio-economic and meteorological conditions, African countries are particularly vulnerable to climate change and its impacts. The recently released IPCC special report "Global Warming of 1.5º C" outlines the fact that keeping global warming by the level of 1.5º C is possible, but also suggested that an increase by 2º C could lead to crises with crops (agriculture fed by rain could drop by 50% in some African countries by 2020) and livestock production, could damage water supplies and pose an additonal threat to coastal areas. The 5th Assessment Report produced by IPCC predicts that wheat may disappear from Africa by 2080, and that maize— a staple—will fall significantly in southern Africa. Also, arid and semi-arid lands are likely to increase by up to 8%, with severe ramifications for livelihoods, poverty eradication and meeting the SDGs. Pursuing appropriate adaptation strategies is thus vital, in order to address the current and future challenges posed by a changing climate. It is against this background that the "African Handbook of Climate Change Adaptation" is being published. It contains papers prepared by scholars, representatives from social movements, practitioners and members of governmental agencies, undertaking research and/or executing climate change projects in Africa, and working with communities across the African continent. Encompassing over 100 contribtions from across Africa, it is the most comprehensive publication on climate change adaptation in Africa ever produced