Blockchain Papers

Simon Cornée

No abstract is available for this record.

Julien Lesgourgues, Sergio Pastor

Neutrinos can play an important role in the evolution of the universe, modifying some of the cosmological observables. In this contribution we summarize the main aspects of cosmological relic neutrinos, and we describe how the precision of present cosmological data can be used to learn about neutrino properties, in particular their mass, providing complementary information to beta decay and neutrinoless double-beta decay experiments. We show how the analysis of current cosmological observations, such as the anisotropies of the cosmic microwave background or the distribution of large-scale structure, provides an upper bound on the sum of neutrino masses of order 1 eV or less, with very good perspectives from future cosmological measurements which are expected to be sensitive to neutrino masses well into the sub-eV range.

Milorad Filipović, Zoran Nјegovan

The main goal of this paper is to establish grounds for a more efficient development of local communities taking into consideration their entire former development characterized by a pronounced polarization and territorial inequality of development exhibited among them in extreme proportions. In view of the insufficient and inadequate decentralization performed without a specific concept in the past, the authors aim to analyze the state of the local infrastructure within the framework of territorial organization offered by the latest regulations, as well as estimate the goals set in the last couple of years by the support programs related to the development of local infrastructure provided by the international institutions. The authors have a similar goal in that sense to provide sufficient argumentation for a quality distribution of local infrastructure and, accordingly, more efficient local development as a prerequisite for a more uniform regional development, especially in rural areas.

Amang Sudarsono, Toru Nakanishi, Nobuo Funabiki

To enhance user privacy, anonymous credential systems allow the user to convince a verifier of the possession of a certificate issued by the issuing authority anonymously. The typical application is the privacy-enhancing electronic ID (eID). Although a previously proposed system achieves the constant complexity in the number of finite-set attributes of the user, it requires the use of RSA. In this paper, we propose a pairing-based anonymous credential system excluding RSA that achieves the constant complexity. The key idea of our proposal is the adoption of a pairing-based accumulator that outputs a constant-size value from a large set of input values. Using zero-knowledge proofs of pairing-based certificates and accumulators, any AND and OR relation can be proved with the constant complexity in the number of finite-set attributes. We implement the proposed system using the fast pairing library, compare the efficiency with the conventional systems, and show the practicality in a mobile eID application.

Melissa Chase, Markulf Kohlweiss, Anna Lysyanskaya, Sarah Meiklejohn

Depending on the application, malleability in cryptography can be viewed as either a flaw or — especially if sufficiently understood and restricted — a feature. In this vein, Chase, Kohlweiss, Lysyanskaya, and Meiklejohn recently defined malleable zero-knowledge proofs, and showed how to control the set of allowable transformations on proofs. As an application, they construct the first compact verifiable shuffle, in which one such controlled-malleable proof suffices to prove the correctness of an entire multi-step shuffle. Despite these initial steps, a number of natural open problems remain: (1) their construction of controlled-malleable proofs relies on the inherent malleability of Groth-Sahai proofs and is thus not based on generic primitives; (2) the classes of allowable transformations they can support are somewhat restrictive; and (3) their construction of a compactly verifiable shuffle has proof size O(N 2 + L) (where N is the number of votes and L is the number of mix authorities), whereas in theory such a proof could be of size O(N + L). In this paper, we address these open problems by providing a generic construction of controlledmalleable proofs using succinct non-interactive arguments of knowledge, or SNARGs for short. Our construction has the advantage that we can support a very general class of transformations (as we no longer rely on the transformations that Groth-Sahai proofs can support), and that we can use it to obtain a proof of size O(N + L) for the compactly verifiable shuffle.

Huaning Cai

Modern engineering and social systems are often too complex to be managed by a centralized agent. Instead, such systems are commonly structured with multiple decentralized agents each responsible for managing a subset of the system, but the resulting system performance depends on the aggregate of the decisions made by decentralized agents. Local agents' decision makings often exhibit selfish behavior as they seek to optimize their own objectives under their localized models, which if left uncoordinated can lead to substantial loss of efficiency compared with the system that can be optimized by a single (hypothetical) centralized agent. In this dissertation, we seek to study the fundamental issues of how to efficiently manage large-scale and multi-agent stochastic dynamic systems, especially on how to device efficient coordination mechanisms that would optimize system performance under various constraints that are unique to decentralized systems.In the first part of this dissertation we study decentralized control of a general class of stochastic dynamic resource allocation problems that have many applications. We consider a stochastic system in which multiple decentralized agents allocate shared system resources in response to customer requests that arrive stochastically over time. Each agent is responsible for a subset of the allocation decisions which it makes according to a dynamic allocation policy obtained by maximizing his own expected profit subject to a potentially mis-specified model of the way in which shared resources are consumed by other agents. We introduce the notion of a transfer contract which specifies how agents compensate one another whenever resources are consumed and establish the existence of contracts under which the decentralized system has no efficiency loss relative to centralized optimality. We also show that this property is insensitive to mis-specification by each agent of the dynamics of resource consumption by others in the system. An explicit characterization of the optimal transfer contract and an iterative decentralized algorithm for computing it is also provided. In the language of duality, contracts are analogous to shadow prices and the iterative algorithm has the favor of a dual update method, but strong duality and convergence of the iterative algorithm to the set of optimal contracts are guaranteed without assumptions of convexity.In the second part of this dissertation we study a class of related decentralized control problems but specialize to portfolio and risk management. Many financial institutions typically trade in multiple correlated markets. While centralized portfolio optimization over all trading decisions is ideal, it is generally not possible due to the complexity of each market, and firms typically adopt a decentralized setup in which trading in each market the responsibility of a particular desk. Decentralized portfolio optimization, however, is complicated by the fact that different agents are commonly only well informed about their own investment universe (proprietary research and forecasts, etc) and prefer to keep this private, and have their own incentives which they optimize on the basis of their limited models. It is well known, however, that the aggregate performance of such a system can be extremely inefficient due to the loss of diversification. In this dissertation, we formulate a multi-agent dynamic portfolio choice problem and study how to improve its efficiency. We show that an internal system of swap contracts, which define internal cash transfers between agents, can be used to facilitate risk sharing and induce agents to choose portfolios that as a collection are optimal for the firm. Conceptually using swap contracts is similar to performance benchmarking that is often employed in the finance literature for decentralized portfolio management, but our new approach offers a significant advantage in that the swap contracts can be constructed in decentralized manner without requiring an all-knowing central agent. We provide an explicit characterization of the optimal swap contracts and an iterative algorithm for computing them that can be implemented without compromising proprietary agent level data.Throughout this dissertation, we also discuss various important issues surrounding decentralized control of stochastic dynamic systems, including but not limited to approximation methods, performance attribution, sensitivity analysis, and fairness issues, etc.

Jørgen Lotz

The Nordic countries are small, unitary, and have largely homogeneous populations. Municipalities are the most important agents in the decentralized public sector and the middle tier (the county level) is losing importance. The expenditure of Nordic local authorities exceeds that in Canada by 10 percent of GDP. The difference represents the effect of local income taxes. Large local expenditures are for kindergartens, primary schools, social welfare, care for the elderly, and culture. These welfare functions are not, however, local public goods; local governments serve mostly as agents for the delivery of national public services. This situation creates complicated problems of control. Amalgamations in several Nordic countries have been carried out to improve the capacity of local authorities to deliver services. Other approaches include joint production and contracting out. The local income tax is a big revenue-raiser, but has some undesirable side effects. Some Nordic countries have a company tax, but this tax raises questions of accountability and fairness, and has been phased out in several places. Nordic countries use methods of tax base equalization which transfer contributions from wealthy jurisdictions to poorer ones. Equalization also involves complicated efforts to deal with the special expenditure needs of cities.

Dieter Zinnbauer

No abstract is available for this record.

Paul E Vaglicia

In 1995, a law professor at the University of Chicago Law School dubbed the Supreme Court confirmation hearings “vapid and hollow” and added that they, as implemented, “serve little educative function, except perhaps to reinforce lessons of cynicism that citizens often glean from government.” Ironically, this same law professor, Elena Kagan, later endured the confirmation hearings as a nominee and currently sits as the 112th Justice of the U.S. Supreme Court. While she may be one of the few to ever reach a seat on the High Court, she is not alone in her assessment of the Supreme Court’s lackluster confirmation process. Other legal scholars have called the process a complete mess and likened it to a circus or a kabuki dance.\nAlthough there are multiple aspects of the confirmation process that could use reform, this Note draws attention to one flaw of the confirmation hearings that many overlook—members of the Senate Judiciary Committee (the “Committee”) use the confirmation hearings as a forum to voice their own political beliefs instead of focusing their undivided attention on the qualifications of the nominee. Since senators do not focus entirely on the nominee, they are not thoroughly examining the nominee’s fitness for the Court. As nationally televised events, it only follows that senators use the confirmation hearings as a medium to speak to theirconstituents. One may ask why this matters or point out that one would expect this of senators; after all, senators constantly have their campaigning caps on, especially when receiving national attention. However, these responses ignore the negative effects of senators placing themselves, rather than the nominees, in the confirmation hearings’ limelight. If the purpose of confirmation hearings is to determine the qualifications of a nominee and ensure that he or she is fit for the Court, then this purpose goes unfulfilled if constituents influence senators’ lines of questioning. Senators consume themselves with how their constituents back home will view their questioning and fail to focus on what is at stake—the confirmation of the nation’s next Supreme Court justice. If the purpose of confirmation hearings is to evaluate the nominee, then this purpose would best be served by having undivided attention focused on the nominee and his or her answers. If senators have an ulterior motive—engaging in an open dialogue with their constituents—then the confirmation process does not effectively serve its primary purpose.\nPart I of this Note investigates the confirmation and appointment power that the Constitution delegates to the Senate. Part II provides a detailed history of the confirmation process and its dramatic evolution over the last century, which is crucial in order to fully comprehend today’s process and its problems. Part III, after examining the media’s role within the confirmation process and the publicity that the confirmation hearings attract, offers proof that senators are cognizant of their national audience and highlights specific examples of senators addressing their constituents via the confirmation hearings. Part IV concludes by setting forth three possible solutions to the overarching problem: implementing anonymous questioning of the nominees through Committee representatives; appointing experts to question the nominees in the senators’ places; and replacing video recording of the hearings with audio recording.

Maria Letitia Andronic

Nowadays, global economy has to face some difficulties, especially since the financial crisis is still a present factor in our economy. This research paper emphasizes the importance of adopting, especially during instability periods, coherent measures by all those who have the power of decision in terms of local budgetary revenue collection and expenditure destination. It is necessary that the regional development dimensions to be conceived according to the diversity of nations, their historical background, but also the cultural, economic and social development discrepancies. We have also underlined the connection between regional development, local autonomy and decentralization, mainly the administrative decentralization, as these concepts define the transfer of responsibilities for the planning, financing and management of certain public functions from the central Government to subordinate units or regional and local authorities. The article focuses on the Global Index of Development and its specific indicators which reveal region’s social-economic and financial performance.

Shantanu Bhattacharya, Sameer Hasija, Luk N. Van Wassenhove

No abstract is available for this record.

Hubert Lacoin, François Simenhaus, Fabio, Lucio Toninelli

Let \mathcal D be a simply connected, smooth enough domain of \mathbb R^2 . For L>0 consider the continuous time, zero-temperature heat bath dynamics for the nearest-neighbor Ising model on \mathbb Z^2 with initial condition such that \sigma_x=-1 if x\in L\mathcal D and \sigma_x=+1 otherwise. It is conjectured [23] that, in the diffusive limit where space is rescaled by L , time by L^2 and L\to\infty , the boundary of the droplet of " - " spins follows a deterministic anisotropic curve-shortening flow, where the normal velocity at a point of its boundary is given by the local curvature times an explicit function of the local slope. The behavior should be similar at finite temperature T<T_c , with a different temperature-dependent anisotropy function. We prove this conjecture (at zero temperature) when \mathcal D is convex. Existence and regularity of the solution of the deterministic curve-shortening flow is not obvious a priori and is part of our result. To our knowledge, this is the first proof of mean curvature-type droplet shrinking for a model with genuine microscopic dynamics.

Sebastian Faust, Markulf Kohlweiss, Giorgia Azzurra Marson, Daniele Venturi

The Fiat-Shamir transform is a well studied paradigm for removing interaction from publiccoin protocols. We investigate whether the resulting non-interactive zero-knowledge (NIZK) proof systems also exhibit non-malleability properties that have up to now only been studied for NIZK proof systems in the common reference string model: first, we formally define simulation soundness and a weak form of simulation extraction in the random oracle model (ROM). Second, we show that in the ROM the Fiat-Shamir transform meets these properties under lenient conditions. A consequence of our result is that, in the ROM, we obtain truly efficient non malleable NIZK proof systems essentially for free. Our definitions are sufficient for instantiating the Naor-Yung paradigm for CCA2-secure encryption, as well as a generic construction for signature schemes from hard relations and simulation-extractable NIZK proof systems. These two constructions are interesting as the former preserves both the leakage resilience and key-dependent message security of the underlying CPA-secure encryption scheme, while the latter lifts the leakage resilience of the hard relation to the leakage resilience of the resulting signature scheme.

John H. Blume, Sheri L. Johnson, Susan E. Millor

"Lennie" refers to Lennie Small, the intellectually disabled character in John Steinbeck's famous novella Of Mice and Men, which tells the story of two Depression-era wandering farmhands, George and Lennie, who dream of getting their own stake and living "off the fat of the land." Their dream dies hard when Lennie accidently kills the young, beautiful, and flirtatious wife of a ranch owner's son and then tries to cover it up because he realizes that he has "done a bad thing." George, in turn, kills Lennie to prevent him from being lynched or tried for murder. Lennie was doomed because he lived in a fictional world where virtually no one understood the nature and severity of his intellectual disability, and thus people were predisposed to believe that Lennie was a cold-blooded murderer who deserved the ultimate punishment. But how would Lennie fare today--not in Steinbeck's fictional Depression-era America, but in the twenty-first century and in our current criminal justice system? Is the criminal justice system equipped to fairly treat mentally retarded defendants in the quest for "truth"? In this article we have argued for a number of procedural protections to safeguard mentally retarded defendants against the heightened risk of wrongful conviction, i.e., providing counsel or an advocate with training in mental retardation, creating safeguards against the admissibility of false confessions, assuring the reliability of informant and codefendant testimony, informing the jury of the heightened risk of error and altering current burdens of proof. We have elected to sketch several procedural protections rather than defend one or another as the most crucial. For any criminal justice system committed to protecting the Lennies of the world against the heigbtened risk of being found guilty of crimes they did not commit, these procedures are a necessary beginning.

Dongsheng Yang

Since the 1980s, decision-making and managerial power has gradually been handed over to higher education institutions in China. This has helped to reduce the government’s financial burden and improve the administrative efficiency of universities. A particular reform involves the establishment of autonomous experimental units within 36 universities. These decentralized units are more highly dependent on market forces than other parts of the university. This thesis examines the development of one such academic unit within one of China’s major universities. The particular academic unit, heretofore referred to as a “school” is studied through a detailed examination of its teaching, research and administration. It is granted a high degree of autonomy to manage itself and its finance. Therefore, it is encouraged to be innovative in its organizational structure and working procedures. This helps drive it to cooperate with industry and adopt a market mechanism in management.\n\nThe research demonstrates the changing relationships of this school with its parent university, with governments at different levels, and with industry and the wider society. The results indicate that a major shift is taking place in Chinese higher education, as China responds with increased marketization and decentralization. \n\nBorrowing theories developed by Clark and Oliver in the fields of higher education and organizational theory, this thesis not only provides a deeper understating of the triangular relationship among universities, state authority and the market, but also refines these theories to suit the Chinese context. This investigation reveals that thus a particular academic unit, unlike most university units in China, must respond to external pressures and expectations in order to survive in a new context of decentralization and commodification. The thesis identifies and analyzes the critical factors affecting the school’s development and its coping strategies within an altered environment of operation.\n\nEmploying a qualitative research methodology, this work views the selected unit of a major Chinese university as an open organizational system, and analyzes the external and internal forces that influence the school’s development. The data collection approach is comprised of semi-structured and unstructured interviews to elicit views and perceptions from the respondents regarding the decision-making, policy implementation and the development of the unit. A focus group interview method is used to question current undergraduate and postgraduate students about perceptions and attitudes towards the development of the unit. Documents are used to obtain background information and to support and triangulate the data collected from individual and group interviews. \n\nAlthough the school failed to make radical changes to the existing university structure and institutions, it has demonstrated the ability to sustain itself, innovate, and gain legitimacy through continuing negotiation and compromise with university authority, government and market. Based on the results of this research, I would argue that if units similar to this one within Chinese universities are granted more administrative autonomy and orient themselves to market forces, Chinese universities will be able to integrate themselves into the increasingly marketized economy and contribute to national development without sacrificing the core academic missions of teaching, research and service.

Olivier Blazy, David Pointcheval, Damien Vergnaud

No abstract is available for this record.

Yulya Yevdokymova

This paper explores school finance management in the context of two different organizational models, rather decentralized Norwegian school management and highly centralized school management in Ukraine. Based on the both cases, the paper analyzes the experience of the school leaders in Norway and Ukraine regarding their budget efforts, and challenges they have met within the framework of the national contexts. It is argued that greater budget autonomy in schools in Ukraine might provide resource and time efficiency. It is discussed that formula-based allocation of money might increase accountability and transparency to the Ukrainian customers of educational services. The study involves deliberations on the possibility to apply greater school autonomy on budget matters in socio-economic context of Ukraine, and a series of policies is proposed, aimed at decentralization of the educational sector.

Mohammad Mahmoody, David Xiao

A Zero-Knowledge PCP (ZK-PCP) is a randomized PCP such that the view of any (perhaps cheating) efficient verifier can be efficiently simulated up to small statistical distance. Kilian, Petrank, and Tardos (STOC '97) constructed ZK-PCPs for all languages in NEXP. Ishai, Mahmoody, and Sahai (TCC '12), motivated by cryptographic applications, revisited the possibility of efficient ZK-PCPs for all of NP where the PCP is encoded as a polynomial-size circuit that given a query i returns the ith symbol of the PCP. Ishai et al showed that there is no efficient ZK-PCP for NP with a non-adaptive verifier, that prepares all of its PCP queries before seeing any answers, unless NP⊆coAM and the polynomial-time hierarchy collapses. The question of whether adaptive verification can lead to efficient ZK-PCPs for NP remained open. In this work, we resolve this question and show that any language or promise problem with efficient ZK-PCPs must be in SZK (the class of promise problems with a statistical zero-knowledge single prover proof system). Therefore, no NP-complete problem can have an efficient ZK-PCP unless NP⊆SZK (which also implies NP⊆coAM and the polynomial-time hierarchy collapses). We prove our result by reducing any promise problem with an efficient ZK-PCP to two instances of the Conditional Entropy Approximation problem defined and studied by Vadhan (FOCS'04) which is known to be complete for the class SZK.

Alma Yadira Quiñonez Carrillo

In recent decades, there has been an increasing interest in systems comprised of several autonomous mobile robots, and as a result, there has been a substantial amount of development in the eld of Articial Intelligence, especially in Robotics. There are several studies in the literature by some researchers from the scientic community that focus on the creation of intelligent machines and devices capable to imitate the functions and movements of living beings. Multi-Robot Systems (MRS) can often deal with tasks that are dicult, if not impossible, to be accomplished by a single robot. In the context of MRS, one of the main challenges is the need to control, coordinate and synchronize the operation of multiple robots to perform a specic task. This requires the development of new strategies and methods which allow us to obtain the desired system behavior in a formal and concise way. This PhD thesis aims to study the coordination of multi-robot systems, in particular, addresses the problem of the distribution of heterogeneous multi-tasks. The main interest in these systems is to understand how from simple rules inspired by the division of labor in social insects, a group of robots can perform tasks in an organized and coordinated way. We are mainly interested on truly distributed or decentralized solutions in which the robots themselves, autonomously and in an individual manner, select a particular task so that all tasks are optimally distributed. In general, to perform the multi-tasks distribution among a team of robots, they have to synchronize their actions and exchange information. Under this approach we can speak of multi-tasks selection instead of multi-tasks assignment, which means, that the agents or robots select the tasks instead of being assigned a task by a central controller. The key element in these algorithms is the estimation ix of the stimuli and the adaptive update of the thresholds. This means that each robot performs this estimate locally depending on the load or the number of pending tasks to be performed. In addition, it is very interesting the evaluation of the results in function in each approach, comparing the results obtained by the introducing noise in the number of pending loads, with the purpose of simulate the robot's error in estimating the real number of pending tasks. The main contribution of this thesis can be found in the approach based on self-organization and division of labor in social insects. An experimental scenario for the coordination problem among multiple robots, the robustness of the approaches and the generation of dynamic tasks have been presented and discussed. The particular issues studied are: Threshold models: It presents the experiments conducted to test the response threshold model with the objective to analyze the system performance index, for the problem of the distribution of heterogeneous multitasks in multi-robot systems; also has been introduced additive noise in the number of pending loads and has been generated dynamic tasks over time. Learning automata methods: It describes the experiments to test the learning automata-based probabilistic algorithms. The approach was tested to evaluate the system performance index with additive noise and with dynamic tasks generation for the same problem of the distribution of heterogeneous multi-tasks in multi-robot systems. Ant colony optimization: The goal of the experiments presented is to test the ant colony optimization-based deterministic algorithms, to achieve the distribution of heterogeneous multi-tasks in multi-robot systems. In the experiments performed, the system performance index is evaluated by introducing additive noise and dynamic tasks generation over time.

Vipul Goyal, Abhishek Jain, Rafail Ostrovsky, Silas Richelson · 5 authors

In this paper we put forward the Bounded Player Model for secure computation. In this new model, the number of players that will ever be involved in secure computations is bounded, but the number of computations has no a priori bound. Indeed, while the number of devices and people on this planet can be realistically estimated and bounded, the number of computations these devices will run can not be realistically bounded. We stress that in the Bounded Player model, in addition to no a priori bound on the number of sessions, there is no synchronization barrier, no trusted party, and simulation must be performed in polynomial time. In this setting, we achieve concurrent Zero Knowledge (cZK) with sub-logarithmic round complexity. Our security proof is (necessarily) non-black-box, our simulator is “straight-line” and works as long as the number of rounds is ω(1). We further show that unlike previously studied relaxations of the standard model (e.g., bounded number of sessions, timing assumptions, super-polynomial simulation), concurrent-secure computation is still impossible to achieve in the Bounded Player model. This gives evidence that our model is “closer” to the standard model than previously studied models, and study of this model might shed light on constructing round efficient concurrent zero-knowledge in the standard model as well.

Rafik Chaabouni, Helger Lipmaa, Bingsheng Zhang

No abstract is available for this record.

Elizabeth Willoughby-Martin

<p>In the last two decades a new form of social movement has spread internationally, characterized by political autonomy, direct action, radical change, and decentralized organization. In response to academic misunderstandings of these new movements, critical geographers have coined the term 'autonomous geographies' to allow effective documentation and communication of these struggles. This research uses autonomous geographies and related discourses to explore how autonomous political collective Camp for Climate Action Aotearoa contributes to the politics of climate change in New Zealand. As an active participant in Camp for Climate Action Aotearoa I have utilized a scholar activist epistemological framework throughout the research process, allowing successful navigation of these interconnected identities. Critical discussion of qualitative data gathered in semi-structured interviews with long-term participants indicates that Camp for Climate Action Aotearoa provides significant support to activists through community and affective solidarity. Camp for Climate Action Aotearoa uses direct action and direct democracy processes which contribute to everyday activist practices and express a non-hegemonic 'logic of affinity'. Data analysis indicates Camp for Climate Action Aotearoa contributes to the creation of alternative futures in the present. These alternative futures are necessary for healthy democracies. Physical climate camps are particularly significant in providing opportunities for creating these alternative visions. Climate Camp Aotearoa is a genuinely political collective that contributes to a repoliticization of climate change in New Zealand.</p>

David Bernhard, Olivier Pereira, Bogdan Warinschi

No abstract is available for this record.

Melissa Chase, Markulf Kohlweiss, Anna Lysyanskaya, Sarah Meiklejohn

Malleability for cryptography is not necessarily an opportunity for attack, but in many cases a potentially useful feature that can be exploited. In this work, we examine notions of malleability for non-interactive zero-knowledge (NIZK) proofs. We start by defining a malleable proof system, and then consider ways to meaningfully control the malleability of the proof system, as in many settings we would like to guarantee that only certain types of transformations can be performed. We also define notions for the cases in which we do not necessarily want a user to know that a proof has been obtained by applying a particular transformation; these are analogous to function/circuit privacy for encryption. As our motivating application, we consider a shorter proof for verifiable shuffles. Our controlled-malleable proofs allow us for the first time to use one compact proof to prove the correctness of an entire multi-step shuffle. Each authority takes as input a set of encrypted votes and a controlled-malleable NIZK proof that these are a shuffle of the original encrypted votes submitted by the voters; it then permutes and re-randomizes these votes and updates the proof by exploiting its controlled malleability. As another application, we generically use controlled-malleable proofs to realize a strong notion of encryption security. Finally, we examine malleability in existing proof systems and observe that Groth-Sahai proofs are malleable. We then go beyond this observation by characterizing all the ways in which they are malleable, and use them to efficiently instantiate our generic constructions from above; this means we can instantiate our proofs and all their applications using only the Decision Linear (DLIN) assumption. Work done as an intern at Microsoft Research Redmond