A bilinear pairing based secure data aggregation scheme for WSNs

End to end secure data aggregation scheme for wireless sensor networks that are based on public key cryptography generally use elliptic curves. However elliptic curve based protocols require messages to be mapped to elliptic curves before performing any operations and finally reverse mapped to retrieve the message back. No mapping function, however, which is both homomorphic and has an efficient reverse mapping function is currently known. The mapping functions used in many previous protocols require brute forcing to reverse map the message from a point on the elliptic curve. This solution may be feasible on a base station with unlimited energy and processing power but it means that decrypting becomes very inefficient on ordinary sensors. We propose a secure data aggregation algorithm based on bilinear pairing that avoids this problem and makes decrypting data feasible on ordinary sensors

The malleability of political attitudes : Choice blindness, confabulation and attitude change

This thesis is an empirical and theoretical investigation of choice blindness, in particular in the domain of political attitudes. Choice blindness is a cognitive phenomenon in which people do not notice dramatic mismatches between what they choose and what they get while still offering seemingly introspective arguments to explain their (putative) choice. In four papers, it is demonstrated that the effect also applies to salient political attitudes and evaluations of political candidates. All studies took place in close connection to real elections, and new tools building of the underlying choice blindness methodology has been developed to collect the data. Further, the potential downstream effects are explored, such as influence on voting intentions, and lasting attitude changes. The potential mechanisms behind the effect are also investigated and confabulatory reasoning stands out as an important part in facilitating the observed attitude changes

Data Sharing on Untrusted Storage with Attribute-Based Encryption

Storing data on untrusted storage makes secure data sharing a challenge issue. On one hand, data access policies should be enforced on these storage servers; on the other hand, confidentiality of sensitive data should be well protected against them. Cryptographic methods are usually applied to address this issue -- only encrypted data are stored on storage servers while retaining secret key(s) to the data owner herself; user access is granted by issuing the corresponding data decryption keys. The main challenges for cryptographic methods include simultaneously achieving system scalability and fine-grained data access control, efficient key/user management, user accountability and etc. To address these challenge issues, this dissertation studies and enhances a novel public-key cryptography -- attribute-based encryption (ABE), and applies it for fine-grained data access control on untrusted storage. The first part of this dissertation discusses the necessity of applying ABE to secure data sharing on untrusted storage and addresses several security issues for ABE. More specifically, we propose three enhancement schemes for ABE: In the first enhancement scheme, we focus on how to revoke users in ABE with the help of untrusted servers. In this work, we enable the data owner to delegate most computation-intensive tasks pertained to user revocation to untrusted servers without disclosing data content to them. In the second enhancement scheme, we address key abuse attacks in ABE, in which authorized but malicious users abuse their access privileges by sharing their decryption keys with unauthorized users. Our proposed scheme makes it possible for the data owner to efficiently disclose the original key owner\u27s identity merely by checking the input and output of a suspicious user\u27s decryption device. Our third enhancement schemes study the issue of privacy preservation in ABE. Specifically, our proposed schemes hide the data owner\u27s access policy not only to the untrusted servers but also to all the users. The second part presents our ABE-based secure data sharing solutions for two specific applications -- Cloud Computing and Wireless Sensor Networks (WSNs). In Cloud Computing cloud servers are usually operated by third-party providers, which are almost certain to be outside the trust domain of cloud users. To secure data storage and sharing for cloud users, our proposed scheme lets the data owner (also a cloud user) generate her own ABE keys for data encryption and take the full control on key distribution/revocation. The main challenge in this work is to make the computation load affordable to the data owner and data consumers (both are cloud users). We address this challenge by uniquely combining various computation delegation techniques with ABE and allow both the data owner and data consumers to securely mitigate most computation-intensive tasks to cloud servers which are envisaged to have unlimited resources. In WSNs, wireless sensor nodes are often unattendedly deployed in the field and vulnerable to strong attacks such as memory breach. For securing storage and sharing of data on distributed storage sensor nodes while retaining data confidentiality, sensor nodes encrypt their collected data using ABE public keys and store encrypted data on storage nodes. Authorized users are given corresponding decryption keys to read data. The main challenge in this case is that sensor nodes are extremely resource-constrained and can just afford limited computation/communication load. Taking this into account we divide the lifetime of sensor nodes into phases and distribute the computation tasks into each phase. We also revised the original ABE scheme to make the overhead pertained to user revocation minimal for sensor nodes. Feasibility of the scheme is demonstrated by experiments on real sensor platforms

Scaling and governance conference 2010 : "Towards a New Knowledge for Scale Sensitive Governance of Complex Systems" : conference program and book of abstracts, Wageningen, the Netherlands November 11-12, 2010

Both the ecological and the socio-economic domain are organized across a multitude of scales and levels. Governance encompasses all those structures and activities of social, political and administrative actors that can be seen as purposeful efforts to guide, steer, control, or manage sustainable development or other moral principles like good governance, accountability or environmental justice

“I Chose to Look Like This”: Body Modification and Regretting Visibility

I began collecting tattoos and piercings just after I turned eighteen. As my collection grows and it becomes harder for me to conceal my modifications, I must contend each and every day with the ways in which my body is Othered by my choice to look different. Body modification is self-actualizing for so many, but it can position someone to be stared at, to be physically violated, to be tokenized, or to be vilified. This current project dissects a few key literature areas, from body modification history to the contemporary politics of modification to aesthetic and spectacular philosophy, with the aim to weave together an argument for a nuanced and complex understanding of the social ramifications of body modification. Focus group interviews bring together numerous body modifiers to discuss the right to look (Mirzoeff, 2011) and the effects of personal choice on marginalization. I look toward two broad questions to guide this project: how do those with visible, non-normative body modifications interact with others, and how do those interactions influence their sense of regret

Malleable zero-knowledge proofs and applications

In recent years, the field of privacy-preserving technologies has experienced considerable expansion, with zero-knowledge proofs (ZKPs) playing one of the most prominent roles. Although ZKPs have been a well-established theoretical construct for three decades, recent efficiency improvements and novel privacy applications within decentralized finance have become the main drivers behind the surge of interest and investment in this area. This momentum has subsequently sparked unprecedented technical advances. Non-interactive ZKPs (NIZKs) are now regularly implemented across a variety of domains, encompassing, but not limited to, privacy-enabling cryptocurrencies, credential systems, voting, mixing, secure multi-party computation, and other cryptographic protocols. This thesis, although covering several areas of ZKP technologies and their application, focuses on one important aspect of NIZKs, namely their malleability. Malleability is a quality of a proof system that describes the potential for altering an already generated proof. Different properties may be desired in different application contexts. On the one end of the spectrum, non-malleability ensures proof immutability, an important requirement in scenarios such as prevention of replay attacks in anonymous cryptocurrencies. At the other end, some NIZKs enable proof updatability, recursively and directly, a feature that is integral for a variety of contexts, such as private smart contracts, compact blockchains, ZK rollups, ZK virtual machines, and MPC protocols generally. This work starts with a detailed analysis of the malleability and overarching security of a popular NIZK, known as Groth16. Here we adopt a more definitional approach, studying certain properties of the proof system, and its setup ceremony, that are crucial for its precise modelling within bigger systems. Subsequently, the work explores the malleability of transactions within a private cryptocurrency variant, where we show that relaxing non-malleability assumptions enables a functionality, specifically an atomic asset swap, that is useful for cryptocurrency applications. The work culminates with a study of a less general, algebraic NIZK, and particularly its updatability properties, whose applicability we present within the context of ensuring privacy for regulatory compliance purposes

Militarism, Security, and War: The Politics of Contemporary Hollywood Superheroes

In the fields of political science and international relations, engagement with popular culture has been deemed predominantly un-important and irrelevant as an area of study. This dissertation interrogates one of the most popular cultural icons of the early 21st century, the fictional Hollywood superhero, and asks what it does for us to take seriously that which is often deemed frivolous entertainment. Understanding the superhero as a political entity in and of itself, this project reveals the mutually constitutive relationship between its production, consumption and reproduction and particular ideologies around militarism, security and war. Acknowledging the complexities of superhero characters, narratives, and aesthetics such as subversive and contested elements, this project reveals superheroes as potential sites of political and ideological reflection, articulation, constitution, and transgression. This project demonstrates that a pop cultural/aesthetic approach to IR can enable critical practices that contribute to complicating and enhancing our understandings of war and politics

Hidden Resources

Vision is central to the human species’ evolution and success. This dependence on sight is reflected in the construction of property frameworks governing natural resources. When humans encounter natural resources they cannot see—hidden resources—they have difficulties imagining an appropriate property regime. As a result, they rely on existing two-dimensional property systems to govern natural resources, which are often three- or four-dimensional in nature. These hidden resources, invisible to the human eye, may be subsurface, distant, or not composed of a visible form. Examples of hidden resources include groundwater, minerals, petroleum, porous space, wind, migratory paths, deep oceans, viruses, and planets. This Article proposes that a lack of natural resource sight affects the ability to efficiently use, manage, and conserve resources. It further examines how revelation of a resource’s latent physical and visual traits results in efficient development and optimal law and policy, concluding that hidden resources should not be governed by the same property frameworks as visible property