http://repository.iiitd.edu.in/xmlui/handle/123456789/5 Sat, 11 Apr 2026 12:42:38 GMT 2026-04-11T12:42:38Z http://repository.iiitd.edu.in/xmlui/handle/123456789/69 MobiShare : cloud-enabled opportunistic content sharing among mobile peers Yadav, Kuldeep; Naik, Vinayak; Singh, Amarjeet In developing countries, smartphones and high bandwidth connections are not yet within the reach of majority of the people. To share multimedia content among themselves, people rely on manual local sharing mechanisms i.e. either using physical exchange of memory card or through short-range wireless technologies, such as Bluetooth. However, this model of content sharing is not scalable in terms of number of users and shared items. In this paper, we propose MobiShare which is a mobilecloud based system designed to support searching and sharing of content among pair of mobile peers. The cloud does aggregation of shared content in user’s social network and enables scalable content search with real-time computation of expected encounter time between content source and requester. For finding expected encounter time, we build algorithms for (1) Finding mobility profiles of the users using heterogeneous location data services such as Cell ID and WiFi; and (2) Predicting places that will be visited in the future, together with corresponding time spent, using those profiles. We deployed MobiShare with 16 volunteers and collected data for 4 weeks. We present evaluation results of the system based on the collected data. Fri, 12 Oct 2012 05:40:45 GMT http://repository.iiitd.edu.in/xmlui/handle/123456789/69 2012-10-12T05:40:45Z http://repository.iiitd.edu.in/xmlui/handle/123456789/38 Take control over your SMSes : a real-world evaluation of a mobile-based spam SMS filtering system Yadav, Kuldeep; Malhotra, Anshu; Kumaraguru, Ponnurangam; Khurana, Rushil; Singh, Dipesh Kumar In developing countries, Short Messaging Service (SMS) is one of the most widely used and cheapest modes of commu- nication. Hence, this medium is often exploited by advertis- ing companies to reach masses. The unsolicited (spam) SM- Ses consume user attention and have become a reason of an- noyance for most of the mobile phone users, as not many of them use the information from these SMSes. We conducted a three phase study to understand the scale of SMS spam problem and to propose technological measures to curb it. First, we conducted a survey among 458 participants in In- dia to understand general perceptions about spam SMSes, user preferences and requirements. Ninety seven percent of the survey participants admitted that they are quite annoyed with the burst of spam SMSes and lack of appropriate tech- nological or regulatory solutions. Next, we designed and implemented a mobile based appli- cation SMSAssassin, which can filter spam SMSes using content based machine learning techniques and user gener- ated customized rules. And last, we conducted a user study of this application with twenty three participants who used the application in real world for a month. Results show that a mobile based solution can effectively filter spam SMSes and the application can be usable too. Wed, 25 Jul 2012 07:56:08 GMT http://repository.iiitd.edu.in/xmlui/handle/123456789/38 2012-07-25T07:56:08Z http://repository.iiitd.edu.in/xmlui/handle/123456789/37 Securing the uncharted territory : transaction receipts in branchless banking Panjwani, Saurabh; Ghosh, Mohona; Kumaraguru, Ponnurangam; Singh, Soumya Vardhan Mobile-based branchless banking has become a key mech- anism for enabling financial inclusion in the developing re- gions of the world. A fundamental requirement of all branch- less banking systems is a mechanism to provide reliable ev- idence to users about the occurrence of transactions, which is implemented in the form of receipts delivered after each transaction. Existing receipt delivery mechanisms, however, provide poor security guarantees to users, which has led to multiple exploits and financial losses recently. In this paper, we present results from two studies conducted with users of a leading branchless banking service in India. Our first study explores current practice with respect to transaction receipts through interviews conducted with 67 users and 87 trans- action observations. The study reveals a desire for robust receipt delivery systems amongst users as well as a preva- lence of insecure practices, which makes users susceptible to fraud. The second study tests usability of receipt verification protocols with 30 users and finds that despite their limited education, users are able to distinguish between secure and insecure interfaces for receipt verification and 37% of them state a strong preference for the secure interface even though it is evidently less convenient. Wed, 25 Jul 2012 07:47:24 GMT http://repository.iiitd.edu.in/xmlui/handle/123456789/37 2012-07-25T07:47:24Z http://repository.iiitd.edu.in/xmlui/handle/123456789/32 Incremental subclass discriminant analysis : a case study in face recognition Lamba, Hemank; Dhamecha, Tejas I; Vatsa, Mayank; Singh, Richa Subclass discriminant analysis is found to be applicable under various scenarios. However, it is computationally very expensive to update the between-class and within-class scatter matrices. This research presents an incremental subclass discriminant analysis algorithm to update SDA in incremental manner with increasing number of samples per class. The effectiveness of the proposed algorithm is demonstrated using face recognition in terms of identification accuracy and training time. Experiments are performed on the AR face database and compared with other subspace based incremental and batch learning algorithms. The results illustrate that Incremental SDA yields significant reduction in time compared to SDA along with improving the accuracy compared to other incremental approaches. Mon, 26 Mar 2012 11:07:57 GMT http://repository.iiitd.edu.in/xmlui/handle/123456789/32 2012-03-26T11:07:57Z