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Research Collection School Of Computing and Information Systems

2009

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Articles 61 - 90 of 194

Full-Text Articles in Physical Sciences and Mathematics

Efficient Conditional Proxy Re-Encryption With Chosen-Ciphertext Security, Jian Weng, Yanjiang Yang, Qiang Tang, Robert H. Deng Sep 2009

Efficient Conditional Proxy Re-Encryption With Chosen-Ciphertext Security, Jian Weng, Yanjiang Yang, Qiang Tang, Robert H. Deng

Research Collection School Of Computing and Information Systems

Recently, a variant of proxy re-encryption, named conditional proxy re-encryption (C-PRE), has been introduced. Compared with traditional proxy re-encryption, C-PRE enables the delegator to implement fine-grained delegation of decryption rights, and thus is more useful in many applications. In this paper, based on a careful observation on the existing definitions and security notions for C-PRE, we re-formalize more rigorous definition and security notions for C-PRE. We further propose a more efficient C-PRE scheme, and prove its chosen-ciphertext security under the decisional bilinear Diffie-Hellman (DBDH) assumption in the random oracle model. In addition, we point out that a recent C-PRE scheme …


Font Size: Make Font Size Smaller Make Font Size Default Make Font Size Larger Exploiting Coordination Locales In Distributed Pomdps Via Social Model Shaping, Pradeep Varakantham, Jun Young Kwak, Matthew Taylor, Janusz Marecki, Paul Scerri, Milind Tambe Sep 2009

Font Size: Make Font Size Smaller Make Font Size Default Make Font Size Larger Exploiting Coordination Locales In Distributed Pomdps Via Social Model Shaping, Pradeep Varakantham, Jun Young Kwak, Matthew Taylor, Janusz Marecki, Paul Scerri, Milind Tambe

Research Collection School Of Computing and Information Systems

Distributed POMDPs provide an expressive framework for modeling multiagent collaboration problems, but NEXPComplete complexity hinders their scalability and application in real-world domains. This paper introduces a subclass of distributed POMDPs, and TREMOR, an algorithm to solve such distributed POMDPs. The primary novelty of TREMOR is that agents plan individually with a single agent POMDP solver and use social model shaping to implicitly coordinate with other agents. Experiments demonstrate that TREMOR can provide solutions orders of magnitude faster than existing algorithms while achieving comparable, or even superior, solution quality.


Accelerating Sequence Searching: Dimensionality Reduction Method, Guojie Song, Bin Cui, Baihua Zheng, Kunqing Xie, Dongqing Yang Sep 2009

Accelerating Sequence Searching: Dimensionality Reduction Method, Guojie Song, Bin Cui, Baihua Zheng, Kunqing Xie, Dongqing Yang

Research Collection School Of Computing and Information Systems

Similarity search over long sequence dataset becomes increasingly popular in many emerging applications, such as text retrieval, genetic sequences exploring, etc. In this paper, a novel index structure, namely Sequence Embedding Multiset tree (SEM − tree), has been proposed to speed up the searching process over long sequences. The SEM-tree is a multi-level structure where each level represents the sequence data with different compression level of multiset, and the length of multiset increases towards the leaf level which contains original sequences. The multisets, obtained using sequence embedding algorithms, have the desirable property that they do not need to keep the …


A Hybrid Firm's Pricing Strategy In Electronic Commerce Under Channel Migration, Robert John Kauffman, Dongwon Lee, Jung Lee, Byungjoon Yoo Sep 2009

A Hybrid Firm's Pricing Strategy In Electronic Commerce Under Channel Migration, Robert John Kauffman, Dongwon Lee, Jung Lee, Byungjoon Yoo

Research Collection School Of Computing and Information Systems

Achieving an effective business design across the Internet and the off-line channel is a critical concern for a hybrid firm's choice of pricing strategy. Two pricing models are proposed to examine how consumer channel migration (one-way channel interaction from the traditional sales channel to the Internet) affects pricing strategy. One model has no interaction between the Internet and off-line channels. The other includes the possibility of one-way migration to the Internet channel and incorporates consumers' channel-switching costs and loyalty to the firm. The two models offer interesting results for understanding traditional and Internet-based selling. A high level of channel migration …


Batch Mode Active Learning With Applications To Text Categorization And Image Retrieval, Steven C. H. Hoi, Rong Jin, Michael R. Lyu Sep 2009

Batch Mode Active Learning With Applications To Text Categorization And Image Retrieval, Steven C. H. Hoi, Rong Jin, Michael R. Lyu

Research Collection School Of Computing and Information Systems

Most machine learning tasks in data classification and information retrieval require manually labeled data examples in the training stage. The goal of active learning is to select the most informative examples for manual labeling in these learning tasks. Most of the previous studies in active learning have focused on selecting a single unlabeled example in each iteration. This could be inefficient, since the classification model has to be retrained for every acquired labeled example. It is also inappropriate for the setup of information retrieval tasks where the user's relevance feedback is often provided for the top K retrieved items. In …


Why Quants Fail, M. Thulasidas Sep 2009

Why Quants Fail, M. Thulasidas

Research Collection School Of Computing and Information Systems

Mathematical finance is built on a couple of assumptions. The most fundamental of them is the one on ma ket efficiency. It states that the market prices every asset fairly, and that the prices contain all the information available in the market.


Admission Control For Differentiated Services In Future Generation Cdma Networks, Hwee-Pink Tan, Rudesindo Núñez-Queija, Adriana F. Gabor, Onno J. Boxma Sep 2009

Admission Control For Differentiated Services In Future Generation Cdma Networks, Hwee-Pink Tan, Rudesindo Núñez-Queija, Adriana F. Gabor, Onno J. Boxma

Research Collection School Of Computing and Information Systems

Future Generation CDMA wireless systems, e.g., 3G, can simultaneously accommodate flow transmissions of users with widely heterogeneous applications. As radio resources are limited, we propose an admission control rule that protects users with stringent transmission bit-rate requirements (“streaming traffic”) while offering sufficient capacity over longer time intervals to delay-tolerant users (“elastic traffic”). While our strategy may not satisfy classical notions of fairness, we aim to reduce congestion and increase overall throughput of elastic users. Using time-scale decomposition, we develop approximations to evaluate the performance of our differentiated admission control strategy to support integrated services with transmission bit-rate requirements in a …


Visible Reverse K-Nearest Neighbor Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Wang-Chien Lee, Ken C. K. Lee, Qing Li Sep 2009

Visible Reverse K-Nearest Neighbor Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Wang-Chien Lee, Ken C. K. Lee, Qing Li

Research Collection School Of Computing and Information Systems

Reverse nearest neighbor (RNN) queries have a broad application base such as decision support, profile-based marketing, resource allocation, etc. Previous work on RNN search does not take obstacles into consideration. In the real world, however, there are many physical obstacles (e.g., buildings) and their presence may affect the visibility between objects. In this paper, we introduce a novel variant of RNN queries, namely, visible reverse nearest neighbor (VRNN) search, which considers the impact of obstacles on the visibility of objects. Given a data set P, an obstacle set O, and a query point q in a 2D space, a VRNN …


Exploiting Bilingual Information To Improve Web Search, Wei Gao, John Bitzer, Ming Zhou, Kam-Fai Wong Aug 2009

Exploiting Bilingual Information To Improve Web Search, Wei Gao, John Bitzer, Ming Zhou, Kam-Fai Wong

Research Collection School Of Computing and Information Systems

Web search quality can vary widely across languages, even for the same information need. We propose to exploit this variation in quality by learning a ranking function on bilingual queries: queries that appear in query logs for two languages but represent equivalent search interests. For a given bilingual query, along with corresponding monolingual query log and monolingual ranking, we generate a ranking on pairs of documents, one from each language. Then we learn a linear ranking function which exploits bilingual features on pairs of documents, as well as standard monolingual features. Finally, we show how to reconstruct monolingual ranking from …


Game Action Based Power Management For Multiplayer Online Game, Bhojan Anand, A. L. Ananda, Mun Choon Chan, Long Thanh Le, Rajesh Krishna Balan Aug 2009

Game Action Based Power Management For Multiplayer Online Game, Bhojan Anand, A. L. Ananda, Mun Choon Chan, Long Thanh Le, Rajesh Krishna Balan

Research Collection School Of Computing and Information Systems

Current mobile devices embrace a wide range of functionalities including high speed network support, hardware accelerated 3D graphics, and multimedia capabilities. These capabilities have boosted the interest for enabling multiplayer online games (MOG) support on such devices. However, the lack of similar growth in battery technology limits the usability of these devices for MOGs. In this paper, we present energy conservation techniques for highly interactive MOGs. These are games, such as first-person shooters, where crisp user interaction is paramount to the overall game experience. Hence, conserving energy while preserving crisp user interaction becomes a critical consideration in this domain. We …


Setting Discrete Bid Levels Adaptively In Repeated Auctions, Jilian Zhang, Hoong Chuin Lau, Jialie Shen Aug 2009

Setting Discrete Bid Levels Adaptively In Repeated Auctions, Jilian Zhang, Hoong Chuin Lau, Jialie Shen

Research Collection School Of Computing and Information Systems

The success of an auction design often hinges on its ability to set parameters such as reserve price and bid levels that will maximize an objective function such as the auctioneer revenue. Works on designing adaptive auction mechanisms have emerged recently, and the challenge is in learning different auction parameters by observing the bidding in previous auctions. In this paper, we propose a non-parametric method for determining discrete bid levels dynamically so as to maximize the auctioneer revenue. First, we propose a non-parametric kernel method for estimating the probabilities of closing price with past auction data. Then a greedy strategy …


Data Mining For Software Engineering, Tao Xie, Suresh Thummalapenta, David Lo, Chao Liu Aug 2009

Data Mining For Software Engineering, Tao Xie, Suresh Thummalapenta, David Lo, Chao Liu

Research Collection School Of Computing and Information Systems

To improve software productivity and quality, software engineers are increasingly applying data mining algorithms to various software engineering tasks. However, mining SE data poses several challenges. The authors present various algorithms to effectively mine sequences, graphs, and text from such data.


Multilayer Image Inpainting Approach Based On Neural Networks, Quan Wang, Zhaoxia Wang, Che Sau Chang, Ting Yang Aug 2009

Multilayer Image Inpainting Approach Based On Neural Networks, Quan Wang, Zhaoxia Wang, Che Sau Chang, Ting Yang

Research Collection School Of Computing and Information Systems

This paper describes an image inpainting approach based on the self-organizing map for dividing an image into several layers, assigning each damaged pixel to one layer, and then restoring these damaged pixels by the information of their respective layer. These inpainted layers are then fused together to provide the final inpainting results. This approach takes advantage of the neural network's ability of imitating human's brain to separate objects of an image into different layers for inpainting. The approach is promising as clearly demonstrated by the results in this paper.


Multi-Task Transfer Learning For Weakly-Supervised Relation Extraction, Jing Jiang Aug 2009

Multi-Task Transfer Learning For Weakly-Supervised Relation Extraction, Jing Jiang

Research Collection School Of Computing and Information Systems

Creating labeled training data for relation extraction is expensive. In this paper, we study relation extraction in a special weakly-supervised setting when we have only a few seed instances of the target relation type we want to extract but we also have a large amount of labeled instances of other relation types. Observing that different relation types can share certain common structures, we propose to use a multi-task learning method coupled with human guidance to address this weakly-supervised relation extraction problem. The proposed framework models the commonality among different relation types through a shared weight vector, enables knowledge learned from …


Optimal-Location-Selection Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li Aug 2009

Optimal-Location-Selection Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li

Research Collection School Of Computing and Information Systems

This paper introduces and solves a novel type of spatial queries, namely, Optimal-Location-Selection (OLS) search, which has many applications in real life. Given a data object set D_A, a target object set D_B, a spatial region R, and a critical distance d_c in a multidimensional space, an OLS query retrieves those target objects in D_B that are outside R but have maximal optimality. Here, the optimality of a target object b \in D_B located outside R is defined as the number of the data objects from D_A that are inside R and meanwhile have their distances to b not exceeding …


Ssnetviz: A Visualization Engine For Heterogeneous Semantic Social Networks, Ee Peng Lim, Maureen Maureen, Nelman Lubis Ibrahim, Aixin Sun, Anwitaman Datta, Kuiyu Chang Aug 2009

Ssnetviz: A Visualization Engine For Heterogeneous Semantic Social Networks, Ee Peng Lim, Maureen Maureen, Nelman Lubis Ibrahim, Aixin Sun, Anwitaman Datta, Kuiyu Chang

Research Collection School Of Computing and Information Systems

SSnetViz is an ongoing research to design and implement a visualization engine for heterogeneous semantic social networks. A semantic social network is a multi-modal network that contains nodes representing di®erent types of people or object entities, and edges representing relationships among them. When multiple heterogeneous semantic social networks are to be visualized together, SSnetViz provides a suite of functions to store heterogeneous semantic social networks, to integrate them for searching and analysis. We will illustrate these functions using social networks related to terrorism research, one crafted by domain experts and another from Wikipedia.


Extracting Paraphrases Of Technical Terms From Noisy Parallel Software Corpus, Xiaoyin Wang, David Lo, Jing Jiang, Lu Zhang, Hong Mei Aug 2009

Extracting Paraphrases Of Technical Terms From Noisy Parallel Software Corpus, Xiaoyin Wang, David Lo, Jing Jiang, Lu Zhang, Hong Mei

Research Collection School Of Computing and Information Systems

In this paper, we study the problem of extracting technical paraphrases from a parallel software corpus, namely, a collection of duplicate bug reports. Paraphrase acquisition is a fundamental task in the emerging area of text mining for software engineering. Existing paraphrase extraction methods are not entirely suitable here due to the noisy nature of bug reports. We propose a number of techniques to address the noisy data problem. The empirical evaluation shows that our method significantly improves an existing method by upto 58%


Inferring Player Rating From Performance Data In Massively Multiplayer Online Role-Playing Games (Mmorpgs), Kyong Jin Shim, Muhammad Aurangzeb Ahmad, Nishith Pathak, Jaideep Srivastava Aug 2009

Inferring Player Rating From Performance Data In Massively Multiplayer Online Role-Playing Games (Mmorpgs), Kyong Jin Shim, Muhammad Aurangzeb Ahmad, Nishith Pathak, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

This paper examines online player performance in EverQuest II, a popular massively multiplayer online role-playing game (MMORPG) developed by Sony Online Entertainment. The study uses the game's player performance data to devise performance metrics for online players. We report three major findings. First, we show that the game's point-scaling system overestimates performances of lower level players and underestimates performances of higher level players. We present a novel point-scaling system based on the game's player performance data that addresses the underestimation and overestimation problems. Second, we present a highly accurate predictive model for player performance as a function of past behavior. …


Symphony: Enabling Search-Driven Applications, John C. Shafer, Rakesh Agrawal, Hady W. Lauw Aug 2009

Symphony: Enabling Search-Driven Applications, John C. Shafer, Rakesh Agrawal, Hady W. Lauw

Research Collection School Of Computing and Information Systems

We present the design of Symphony, a platform that enables non-developers to build and deploy a new class of search-driven applications that combine their data and domain expertise with content from search engines and other web services. The Symphony prototype has been built on top of Microsoft’s Live Search infrastructure. While Symphony naturally makes use of the customization capabilities exposed by Live Search, its distinguishing feature is the capability it provides to the application creator to combine their proprietary data and domain expertise with content obtained from Live Search. They can also integrate specialized data obtained from web services to …


A Distributed Spatial Index For Error-Prone Wireless Data Broadcast, Baihua Zheng, Wang-Chien Lee, Ken C. K. Lee, Dik Lun Lee, Min Shao Aug 2009

A Distributed Spatial Index For Error-Prone Wireless Data Broadcast, Baihua Zheng, Wang-Chien Lee, Ken C. K. Lee, Dik Lun Lee, Min Shao

Research Collection School Of Computing and Information Systems

Information is valuable to users when it is available not only at the right time but also at the right place. To support efficient location-based data access in wireless data broadcast systems, a distributed spatial index (called DSI) is presented in this paper. DSI is highly efficient because it has a linear yet fully distributed structure that naturally shares links in different search paths. DSI is very resilient to the error-prone wireless communication environment because interrupted search operations based on DSI can be resumed easily. It supports search algorithms for classical location-based queries such as window queries and kNN queries …


Evaluating Straddle Carrier Deployment Policies: A Simulation Study For The Piraeus Container Terminal, Eleni Hadjiconstantinou, Nang Laik Ma Aug 2009

Evaluating Straddle Carrier Deployment Policies: A Simulation Study For The Piraeus Container Terminal, Eleni Hadjiconstantinou, Nang Laik Ma

Research Collection School Of Computing and Information Systems

Most container terminals in the world today are operating up to their capacities. In this paper, we have developed a decision support system to optimise yard operations by considering all container flows (import, export and transshipment) through the yard with the view to improving the terminal performance and efficiency. In another paper, we proposed an optimisation model that determines optimal container locations and straddle carrier (SC) movements with the objective of minimising the overall storage and handling cost of containers. In this paper, a discrete event simulation tool for container terminal operations has been developed with three objectives: (i) to …


On Efficient Mutual Nearest Neighbor Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li Aug 2009

On Efficient Mutual Nearest Neighbor Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li

Research Collection School Of Computing and Information Systems

This paper studies a new form of nearest neighbor queries in spatial databases, namely, mutual nearest neighbour (MNN) search. Given a set D of objects and a query object q, an MNN query returns from D, the set of objects that are among the k1 (≥ 1) nearest neighbors (NNs) of q; meanwhile, have q as one of their k2(≥ 1) NNs. Although MNN queries are useful in many applications involving decision making, data mining, and pattern recognition, it cannot be efficiently handled by existing spatial query processing approaches. In this paper, we present …


A Fair Assignment Algorithm For Multiple Preference Queries, Leong Hou U, Nikos Mamoulis, Kyriakos Mouratidis Aug 2009

A Fair Assignment Algorithm For Multiple Preference Queries, Leong Hou U, Nikos Mamoulis, Kyriakos Mouratidis

Research Collection School Of Computing and Information Systems

Consider an internship assignment system, where at the end of each academic year, interested university students search and apply for available positions, based on their preferences (e.g., nature of the job, salary, office location, etc). In a variety of facility, task or position assignment contexts, users have personal preferences expressed by different weights on the attributes of the searched objects. Although individual preference queries can be evaluated by selecting the object in the database with the highest aggregate score, in the case of multiple simultaneous requests, a single object cannot be assigned to more than one users. The challenge is …


Scalable Verification For Outsourced Dynamic Databases, Hwee Hwa Pang, Jilian Zhang, Kyriakos Mouratidis Aug 2009

Scalable Verification For Outsourced Dynamic Databases, Hwee Hwa Pang, Jilian Zhang, Kyriakos Mouratidis

Research Collection School Of Computing and Information Systems

Query answers from servers operated by third parties need to be verified, as the third parties may not be trusted or their servers may be compromised. Most of the existing authentication methods construct validity proofs based on the Merkle hash tree (MHT). The MHT, however, imposes severe concurrency constraints that slow down data updates. We introduce a protocol, built upon signature aggregation, for checking the authenticity, completeness and freshness of query answers. The protocol offers the important property of allowing new data to be disseminated immediately, while ensuring that outdated values beyond a pre-set age can be detected. We also …


Essential Spreadsheet Modeling Course For Business Students, Thin Yin Leong, Michelle L. F. Cheong Aug 2009

Essential Spreadsheet Modeling Course For Business Students, Thin Yin Leong, Michelle L. F. Cheong

Research Collection School Of Computing and Information Systems

Ask any student at the Singapore Management University (SMU) to name one of the most practical and useful courses offered by the university. The answer would inevitably include CAT. CAT stands for the "Computer as an Analysis Tool" course. Originally based on a course of the same title offered by the Wharton Business School, the focus of CAT was shifted to provide business students the essential practical skills and necessary "real-world" exposure to better use personal computers for resolving business problems. The course is basically centered on using the Excel spreadsheet to work on ambiguous ill-defined problems.


Formal Verification Of Scalable Nonzero Indicators, Jun Sun, Yang Liu, Jun Sun, Jin Song Dong, Wei Chen, Yanhong A. Liu Jul 2009

Formal Verification Of Scalable Nonzero Indicators, Jun Sun, Yang Liu, Jun Sun, Jin Song Dong, Wei Chen, Yanhong A. Liu

Research Collection School Of Computing and Information Systems

Concurrent algorithms are notoriously difficult to design correctly, and high performance algorithms that make little or no use of locks even more so. In this paper, we describe a formal verification of a recent concurrent data structure Scalable NonZero Indicators. The algorithm supports incrementing, decrementing, and querying the shared counter in an efficient and linearizable way without blocking. The algorithm is highly non-trivial and it is challenging to prove the correctness. We have proved that the algorithm satisfies linearizability, by showing a trace refinement relation from the concrete implementation to its abstract specification. These models are specified in CSP and …


Poster Abstract: Beamcast: Harnessing Beamforming Capabilities For Link Layer Multicast, Souvik Sen, Rahul Ghosh, Jie Xiong, Romit Roy Choudhury Jul 2009

Poster Abstract: Beamcast: Harnessing Beamforming Capabilities For Link Layer Multicast, Souvik Sen, Rahul Ghosh, Jie Xiong, Romit Roy Choudhury

Research Collection School Of Computing and Information Systems

Wireless multicast is an important service primitive for emerging applications such as live video, streaming audio and content telecasts. Transmission rate in such a link layer multicast is bottlenecked by the rate of the weakest client, leading to channel under-utilization. Attempts to increase the data rate results in lower reliability (due to higher bit error rate) and higher unfairness. This poster utilizes smart beamforming antennas to improve multicast performance in wireless LANs. The main idea is to satisfy majority of the (strong) clients with a high-rate omnidirectional transmission, followed by high-rate directional transmission(s) to cover the weaker ones. By selecting …


Ktr: An Efficient Key Management Scheme For Secure Data Access Control In Wireless Broadcast Services Recovery, Qijun Gu, Peng Liu, Wang-Chien Lee, Chao-Hsien Chu Jul 2009

Ktr: An Efficient Key Management Scheme For Secure Data Access Control In Wireless Broadcast Services Recovery, Qijun Gu, Peng Liu, Wang-Chien Lee, Chao-Hsien Chu

Research Collection School Of Computing and Information Systems

Wireless broadcast is an effective approach for disseminating data to a number of users. To provide secure access to data in wireless broadcast services, symmetric-key-based encryption is used to ensure that only users who own the valid keys can decrypt the data. With regard to various subscriptions, an efficient key management for distributing and changing keys is in great demand for access control in broadcast services. In this paper, we propose an efficient key management scheme, namely, key tree reuse (KTR), to handle key distribution with regard to complex subscription options and user activities. KTR has the following advantages. First, …


Identifying Bug Signatures Using Discriminative Graph Mining, Hong Cheng, David Lo, Yang Zhou, Xiaoyin Wang, Xifeng Yan Jul 2009

Identifying Bug Signatures Using Discriminative Graph Mining, Hong Cheng, David Lo, Yang Zhou, Xiaoyin Wang, Xifeng Yan

Research Collection School Of Computing and Information Systems

Bug localization has attracted a lot of attention recently. Most existing methods focus on pinpointing a single statement or function call which is very likely to contain bugs. Although such methods could be very accurate, it is usually very hard for developers to understand the context of the bug, given each bug location in isolation. In this study, we propose to model software executions with graphs at two levels of granularity: methods and basic blocks. An individual node represents a method or basic block and an edge represents a method call, method return or transition (at the method or basic …


Conditional Proxy Broadcast Re-Encryption, Cheng-Kang Chu, Jian Weng, Sherman S. W. Chow, Jianying Zhou, Robert H. Deng Jul 2009

Conditional Proxy Broadcast Re-Encryption, Cheng-Kang Chu, Jian Weng, Sherman S. W. Chow, Jianying Zhou, Robert H. Deng

Research Collection School Of Computing and Information Systems

A proxy re-encryption (PRE) scheme supports the delegation of decryption rights via a proxy, who makes the ciphertexts decryptable by the delegatee. PRE is useful in various applications such as encrypted email forwarding. In this paper, we introduce a more generalized notion of conditional proxy broadcast re-encryption (CPBRE). A CPBRE scheme allows Alice to generate a re-encryption key for some condition specified during the encryption, such that the re-encryption power of the proxy is restricted to that condition only. This enables a more fine-grained delegation of decryption right. Moreover, Alice can delegate decryption rights to a set of users at …