Functional encryption for threshold functions (or fuzzy IBE) from lattices

Cryptosystems based on the hardness of lattice problems have recently acquired much importance due to their average-case to worst-case equivalence, their conjectured resistance to quantum cryptanalysis, their ease of implementation and increasing practicality, and, lately, their promising potential as a platform for constructing advanced functionalities. In this work, we construct “Fuzzy” Identity Based Encryption from the hardness of the Learning With Errors (LWE) problem. We note that for our parameters, the underlying lattice problems (such as gapSVP or SIVP) are assumed to be hard to approximate within supexponential factors for adversaries running in subexponential time. We give CPA and CCA secure variants of our construction, for small and large universes of attributes. All our constructions are secure against selective-identity attacks in the standard model. Our construction is made possible by observing certain special properties that secret sharing schemes need to satisfy in order to be useful for Fuzzy IBE. We also discuss some obstacles towards realizing lattice-based attribute-based encryption (ABE).

Lattice basis delegation in fixed dimension and shorter-ciphertext hierarchical IBE

We present a technique for delegating a short lattice basis that has the advantage of keeping the lattice dimension unchanged upon delegation. Building on this result, we construct two new hierarchical identity-based encryption (HIBE) schemes, with and without random oracles. The resulting systems are very different from earlier lattice-based HIBEs and in some cases result in shorter ciphertexts and private keys. We prove security from classic lattice hardness assumptions.

A tapestry of identity-based encryption : practical frameworks compared

This paper surveys the practical benefits and drawbacks of several identity-based encryption schemes based on bilinear pairings. After providing some background on identity-based cryptography, we classify the known constructions into a handful of general approaches. We then describe efficient and fully secure IBE and IBKEM instantiations of each approach, with reducibility to practice as the main design parameter. Finally, we catalogue the strengths and weaknesses of each construction according to a few theoretical and many applied comparison criteria.

Flexible IBE and beyond in the commutative-blinding framework

The cryptographic community has, of late, shown much inventiveness in the creation of powerful new IBE-like primitives that go beyond the basic IBE notion and extend it in many new directions. Virtually all of these “super-IBE” schemes rely on bilinear pairings for their implementation, which they tend to use in a surprisingly small number of different ways: three of them as of this writing. What is interesting is that, among the three main frameworks that we know of so far, one has acted as a veritable magnet for the construction of many of these “generalized IBE” primitives, whereas the other two have not been nearly as fruitful in that respect. This refers to the Commutative Blinding framework defined by the Boneh-Boyen [Bscr ][Bscr ]1 IBE scheme from 2004. The aim of this chapter is to try to shed some light on this approach's popularity, first by comparing its key properties with those of the competing frameworks, and then by providing a number of examples that illustrate how those properties have been used.

New security notions and relations for public-key encryption

Since their introduction, the notions of indistinguishability and non-malleability have been changed and extended by different authors to support different goals. In this paper, we propose new flavors of these notions, investigate their relative strengths with respect to previous notions, and provide the full picture of relationships (i.e., implications and separations) among the security notions for public-key encryption schemes. We take into account the two general security goals of indistinguishability and non-malleability, each in the message space, key space, and hybrid message-key space to find six specific goals, a couple of them, namely complete indistinguishability and key non-malleability, are new. Then for each pair of goals, coming from the indistinguishability or non-malleability classes, we prove either an implication or a separation, completing the full picture of relationships among all these security notions. The implications and separations are respectively supported by formal proofs (i.e., reductions) in the concrete-security framework and by counterexamples.

Lattice-based completely non-malleable public-key encryption in the standard model

An encryption scheme is non-malleable if giving an encryption of a message to an adversary does not increase its chances of producing an encryption of a related message (under a given public key). Fischlin introduced a stronger notion, known as complete non-malleability, which requires attackers to have negligible advantage, even if they are allowed to transform the public key under which the related message is encrypted. Ventre and Visconti later proposed a comparison-based definition of this security notion, which is more in line with the well-studied definitions proposed by Bellare et al. The authors also provide additional feasibility results by proposing two constructions of completely non-malleable schemes, one in the common reference string model using non-interactive zero-knowledge proofs, and another using interactive encryption schemes. Therefore, the only previously known completely non-malleable (and non-interactive) scheme in the standard model, is quite inefficient as it relies on generic NIZK approach. They left the existence of efficient schemes in the common reference string model as an open problem. Recently, two efficient public-key encryption schemes have been proposed by Libert and Yung, and Barbosa and Farshim, both of them are based on pairing identity-based encryption. At ACISP 2011, Sepahi et al. proposed a method to achieve completely non-malleable encryption in the public-key setting using lattices but there is no security proof for the proposed scheme. In this paper we review the mentioned scheme and provide its security proof in the standard model. Our study shows that Sepahi’s scheme will remain secure even for post-quantum world since there are currently no known quantum algorithms for solving lattice problems that perform significantly better than the best known classical (i.e., non-quantum) algorithms.

Multi-party computation with conversion of secret sharing

Classical results in unconditionally secure multi-party computation (MPC) protocols with a passive adversary indicate that every n-variate function can be computed by n participants, such that no set of size t < n/2 participants learns any additional information other than what they could derive from their private inputs and the output of the protocol. We study unconditionally secure MPC protocols in the presence of a passive adversary in the trusted setup (‘semi-ideal’) model, in which the participants are supplied with some auxiliary information (which is random and independent from the participant inputs) ahead of the protocol execution (such information can be purchased as a “commodity” well before a run of the protocol). We present a new MPC protocol in the trusted setup model, which allows the adversary to corrupt an arbitrary number t < n of participants. Our protocol makes use of a novel subprotocol for converting an additive secret sharing over a field to a multiplicative secret sharing, and can be used to securely evaluate any n-variate polynomial G over a field F, with inputs restricted to non-zero elements of F. The communication complexity of our protocol is O(ℓ · n 2) field elements, where ℓ is the number of non-linear monomials in G. Previous protocols in the trusted setup model require communication proportional to the number of multiplications in an arithmetic circuit for G; thus, our protocol may offer savings over previous protocols for functions with a small number of monomials but a large number of multiplications.

Generalized IBE in the exponent-inversion framework

The purpose of this chapter is to provide an abstraction for the class of Exponent-Inversion IBE exemplified by the [Bscr ][Bscr ]2 and [Sscr ][Kscr ] schemes, and, on the basis of that abstraction, to show that those schemes do support interesting and useful extensions such as HIBE and ABE. Our results narrow, if not entirely close, the “flexibility gap” between the Exponent-Inversion and Commutative-Blinding IBE concepts.

The development of an effective and efficient dispute resolution processes for strata scheme disputes in peninsular Malaysia

Dispute resolution in strata schemes in Peninsular Malaysia should focus on more than just "settlement." The quality of the outcome, its sustainability and its relevance in supporting the basic principles of a good neighbourhood and self-governance in a strata scheme are also fundamental. Based on the comprehensive law movement, this thesis develops a theoretical framework for strata scheme disputes within the parameters of therapeutic jurisprudence, preventive law, alternative dispute resolution (ADR) and problem-solving courts. The therapeutic orientation of this model offers approaches that promote positive communication between disputing parties, preserve neighbour relations and optimise people's psychological and emotional well-being.

Using a public key registry for improved trust and scalability in national E-health systems

An increasing number of countries are faced with an aging population increasingly needing healthcare services. For any e-health information system, the need for increased trust by such clients with potentially little knowledge of any security scheme involved is paramount. In addition notable scalability of any system has become a critical aspect of system design, development and ongoing management. Meanwhile cryptographic systems provide the security provisions needed for confidentiality, authentication, integrity and non-repudiation. Cryptographic key management, however, must be secure, yet efficient and effective in developing an attitude of trust in system users. Digital certificate-based Public Key Infrastructure has long been the technology of choice or availability for information security/assurance; however, there appears to be a notable lack of successful implementations and deployments globally. Moreover, recent issues with associated Certificate Authority security have damaged trust in these schemes. This paper proposes the adoption of a centralised public key registry structure, a non-certificate based scheme, for large scale e-health information systems. The proposed structure removes complex certificate management, revocation and a complex certificate validation structure while maintaining overall system security. Moreover, the registry concept may be easier for both healthcare professionals and patients to understand and trust.

Improving megasite management performance through incentives : lessons learned from the Shanghai Expo construction

As the biggest expo site in history, construction of the Shanghai Expo site faced a lot of challenges, including involvement of lots of investors, megaconstruction scale, concurrent construction mode, involvement of more than 40,000 migrant workers, and extremely tight completion deadlines, among others. Consequently, these challenges imposed great obstacles on accomplishing the safety, quality, and environmental goals. Through a case study of the Shanghai Expo construction, this paper paper presents the design and implementation of multicriteria incentives in megaprojects to accomplish the safety, quality, and environmental goals. Both quantitative and qualitative findings were triangulated to demonstrate the outcome of the incentives. Six critical success factors (CSFs) for the incentives, rule design, process orientation, top management support, training and promotion, communication in process, and process learning and improvement are identified and validated through case study data and content analysis. It is believed that the findings of this paper can enhance understanding of multicriteria incentive schemes in general and provide insights in implementing these incentive schemes in future megaprojects, particularly in the People’s Republic of China (PRC).

Parallel Signcryption

The primary motivation for signcryption was the gain in efficiency when both encryption and signing need to be performed. These two cryptographic operations may be done sequentially either by first encrypt and then sign (EtS) or alternatively, by first sign and then encrypt (StE). Further gains in efficiency can be achieved if encryption and signature are carried out in parallel (E&S). More importantly, however, is that these efficiency gains are complemented by gains in security, i.e., we may use relative weak encryption and signature schemes in order to obtain a “stronger” signcryption scheme. The reader is referred to Chaps. 2 and 3 for a discussion of the different “strengths” of security model (e.g., outsider vs. insider adversaries, two-user vs. multi-user setting).

Crypto topics and applications II

In this chapter we continue the exposition of crypto topics that was begun in the previous chapter. This chapter covers secret sharing, threshold cryptography, signature schemes, and finally quantum key distribution and quantum cryptography. As in the previous chapter, we have focused only on the essentials of each topic. We have selected in the bibliography a list of representative items, which can be consulted for further details. First we give a synopsis of the topics that are discussed in this chapter. Secret sharing is concerned with the problem of how to distribute a secret among a group of participating individuals, or entities, so that only predesignated collections of individuals are able to recreate the secret by collectively combining the parts of the secret that were allocated to them. There are numerous applications of secret-sharing schemes in practice. One example of secret sharing occurs in banking. For instance, the combination to a vault may be distributed in such a way that only specified collections of employees can open the vault by pooling their portions of the combination. In this way the authority to initiate an action, e.g., the opening of a bank vault, is divided for the purposes of providing security and for added functionality, such as auditing, if required. Threshold cryptography is a relatively recently studied area of cryptography. It deals with situations where the authority to initiate or perform cryptographic operations is distributed among a group of individuals. Many of the standard operations of single-user cryptography have counterparts in threshold cryptography. Signature schemes deal with the problem of generating and verifying electronic) signatures for documents.Asubclass of signature schemes is concerned with the shared-generation and the sharedverification of signatures, where a collaborating group of individuals are required to perform these actions. A new paradigm of security has recently been introduced into cryptography with the emergence of the ideas of quantum key distribution and quantum cryptography. While classical cryptography employs various mathematical techniques to restrict eavesdroppers from learning the contents of encrypted messages, in quantum cryptography the information is protected by the laws of physics.

Lattice-based completely non-malleable PKE in the standard model

This paper presents ongoing work toward constructing efficient completely non-malleable public-key encryption scheme based on lattices in the standard (common reference string) model. An encryption scheme is completely non-malleable if it requires attackers to have negligible advantage, even if they are allowed to transform the public key under which the related message is encrypted. Ventre and Visconti proposed two inefficient constructions of completely non-malleable schemes, one in the common reference string model using non-interactive zero-knowledge proofs, and another using interactive encryption schemes. Recently, two efficient public-key encryption schemes have been proposed, both of them are based on pairing identity-based encryption.

Living City 2013 Workshop

Living City 2013 Workshop, as part of a school term’s design-based curriculum connected to the KGSC/QUT Design Excellence Program and run from 11 February – 1 May, 2013, was essentially a three-day place-based urban design immersion workshop program for 25 Year 11 Visual Art and Design Students and 2 Teachers from Kelvin Grove State College (KGSC) held at both Queensland University of Technology (QUT) Gardens Point Campus and The Edge, State Library of Queensland. Mentored by 4 design professionals, 2 tertiary design academics, 2 public artists, and 12 QUT tertiary design students, the workshop explored youth-inspired public space design solutions for the active Brisbane City Council redevelopment site of Queens Wharf Road precinct. As well as the face-to-face workshops, for Living City 2013, an interactive web environment was introduced to enable students to connect with each other and program mentors throughout the course of the program. The workshop, framed within notions of ecological, economic, social and cultural sustainability, aimed to raise awareness of the layered complexity and perspectives involved in the design of shared city spaces and to encourage young people to voice their own concerns as future citizens about the shape and direction of their city. The program commenced with an introductory student briefing by stakeholders and mentors at KGSC on 11 February, an introduction to site appraisal and site visit held at QUT and Queens Wharf Road on 20 February, and a follow up site analysis session on 6 March. Day 1 Workshop on April 17 at the Edge, State Library of Queensland, as part of the Design Minds partnership (http://designminds.org.au/kelvin-grove-state-college-excellence-in-art-design/), focused on mentoring team development of a concept design for a range of selected sites. Two workshops on April 22 and 23 at QUT, to develop these designs and presentation schemes, followed this. The workshop program culminated in a visual presentation of concept design ideas and discussion with a public audience in the Ideas Gallery on The Deck, King George Square during the Brisbane City Council City Centre Master Plan Ideas Fiesta on 1 May, 2013, as referenced in the Ideas Fiesta Wrap-up Report (http://www.brisbane.qld.gov.au/planning-building/planning-guidelines-tools/city-centre-master-plan/city-centre-master-plan-ideas-fiesta). Students were introduced to design methodology, team thinking strategies, the scope of design practices and professions, presentation skills and post-secondary pathways, while participating teachers acquired content and design learning strategies transferable in many other contexts. The program was fully documented on the Living City website (http://www.livingcity.net.au/LC2013x/index.html) and has been recognised by the Brisbane City Council Youth Strategy 2014-2019 as a best practice model for making Brisbane a well-designed, subtropical city.