Serena Nicolazzo

Comparing Twitter and Facebook user behavior

We compare the behavior of users who belong to both Twitter and Facebook.We adopt a truly multi-OSN perspective by basing our analysis on membership overlap.We study overlapping friendship, user activity, degree, and privacy awareness. Understanding online-social-network (OSN) user behavior is an important challenge in the field of social network analysis, as OSNs play a significant role in peoples daily lives. So far, many studies considering only one OSN or, at most, comparing results obtained for a single OSN, have been provided. Nowadays, users typically join more OSNs and this is an important aspect that should be taken into account for user behavior analysis. In this paper, we give an important contribution in this direction, by analyzing the behavior of users belonging to both Facebook and Twitter. This way, the analysis is well-founded because it is conducted on a common set of users and, further, a number of specific analyses become possible (as common friendship). Our study is carried out on data extracted from the web, and allows us to find important specificities of these users about their privacy setting, the choice of friends and the activity they do, which are generally consistent with the recent findings in this field.

Driving Global Team Formation in Social Networks to Obtain Diversity

In this paper, we present a preliminary idea for a crowdsourcing application aimed at driving the process of global team formation to obtain diversity in the team. Indeed, it is well known that diversity is one of the key factors of collective intelligence in crowdsourcing. The idea is based on the identification of suitable nodes in social networks, which can profitably play the role of generators of diversity in the team formation process. This paper presents a first step towards the concrete definition of the above application consisting in the identification of an effective measure that can be used to select the most promising nodes w.r.t. the above feature.

A model to support design and development of multiple-social-network applications

Online social networks have become so pervasive in peoples lives that they can play a crucial role in design and development processes of applications. At moment, a gap exists w.r.t. standard networking programming to support social-network-based programming in large, according to software engineering principles of genericity and polymorphism. This drawback is made evident when applications should be built on top of multiple social networks and the user-centered vision should be kept. Indeed, heterogeneity of social networks does not allow us to produce software with suitable abstraction. In this paper, we cover the above gap by defining and implementing a model aimed at generalizing concepts, actions and relationships of existing social networks. The effectiveness of our approach is shown by two case studies.

A Model to Support Multi-Social-Network Applications

It is not uncommon that people create multiple profiles in different social networks, spreading out over them personal information. This leads to a multi-social-network scenario where different social networks cannot be viewed as monads, but are strongly correlated to each other. Building a suitable middleware on top of social networks to support internetworking applications is an important challenge, as the global view of the social network world provides very powerful knowledge and opportunities. In this paper, we do a first important step towards this goal, by defining and implementing a model aimed at generalizing concepts, actions and relationships of existing social networks.

A Privacy-Preserving Solution for Tracking People in Critical Environments

In critical environments a high level of security and safety is required, leading to the necessity of controlling as much as possible physical access and localization of people. An effective possibility for tracking people is based on the use of RFIDs, in such a way to have logs reporting people localization at any time. This way, the (a-posteriori) analysis of logs can provide decisive information in case of a security/safety incident. Unfortunately, in most cases, a similar solution is intolerable for privacy reasons, so that finding a good solution of the trade-off between people privacy and security/safety requirements assumes a very important role. This paper proposes an RFID-based technique to trace people but introducing a certain degree of uncertainty, in such a way that their privacy is fully preserved. This approach implements the k-anonymity property for which we are able to guess who accessed a place, at a given time, with probability k-1. An important aspect of our technique is that it is implementable via very cheap RFID tags, thus making our proposal really concrete and attractive. The experimental evaluation shows the capability of the proposed method to reach the aimed results.

Measuring Betweenness Centrality in Social Internetworking Scenarios

The importance of the betweenness centrality measure in (on-line) social networks is well known, as well as its possible applications to various domains. However, the classical notion of betweenness centrality is not able to capture the centrality of nodes w.r.t. paths crossing different social networks. In other words, it is not able to detect those nodes of a multi-social-network scenario (called Social Internetworking Scenario) which play a central role in inter-social-network information flows. In this paper, we propose a new measure of betweenness centrality suitable for Social Internetworking Scenarios, also applicable to the case of different communities of the same social network. The new measure has been tested in a number of synthetic networks, highlighting the significance and effectiveness of our proposal.

Accountability-Preserving Anonymous Delivery of Cloud Services

Cloud computing is an emerging paradigm whose importance both in large and small business is more and more increasing. As one of the reasons motivating the adoption of cloud computing solutions is to alleviate the load of companies related to the solution of security and disaster recovery issues, security is one of the main features to fulfill in a cloud computing system. Moreover, a number of new security and privacy problems arise, such as threats to user’s privacy due to the realistic possibility of having honest-but-curious cloud providers. In this scenario, we propose an authentication scheme supporting full anonymity of users and unlinkability of service requests. This is done by combining a multi-party cryptographic protocol with the use of a cooperative P2P-based approach to access services in the cloud. As the solution is thought to be adopted in e-government scenarios, accountability of user accesses is always preserved, to prevent misuse and illegal actions of users.

Tweetchain: An Alternative to Blockchain for Crowd-Based Applications

The assurance of information in the crowdsourcing domain cannot be committed to a single party, but should be distributed over the crowd. Blockchain is an infrastructure allowing this, because transactions are broadcast to the entire community and verified by miners. A node (or a coalition of nodes) with high computational power can play the role of miner to verify and approve transactions by computing the proof of work. Miners follows a highest-fee-first-served policy, so that a provider of a Blockchain-based application has to pay a non-negligible fee per transaction, to increase the likelihood that the application proceeds. This makes Blockchain not suitable for small-value transactions often occurring in the crowdsourcing paradigm. To overcome this drawback, in this paper we propose an alternative to Blockchain, leveraging an online social network (we choose Twitter to provide a proof of concept). Our protocol works by building a meshed chain of public posts to ensure transaction security instead of proof of work, and no trustworthiness assumption is required for the social network provider.

A New Approach for Electronic Signature

There are many application contexts in which guaranteeing authenticity and integrity of documents is essential. In these cases, the typical solution relies on digital signature, which is based on the use of a PKI infrastructure and suitable devices (smart card or token USB). For several reasons, including certificate and device cost, many countries, such as the United States, the European Union, India, Brazil and Australia, have introduced the possibility to use simple generic electronic signature , which is less secure but reduces the drawbacks of digital signature.In this paper, we propose a new type of electronic signature that is based on the use of social networks. We formalize the proposal in a generic scenario and then, show a possible implementation on Twitter. Our proposal is proved to be secure, cheap and simple to adopt.

Range Query Integrity in Cloud Data Streams with Efficient Insertion

Cloud computing provides users with the possibility to store their data in third-party servers. These data centers may be untrusted or susceptible to attacks, hence they could return compromised query results once interrogated. Query integrity has been widely investigated in the literature, and a number of methods have been proposed to allow users to verify that query results are complete (i.e., no qualifying tuples are omitted), fresh (i.e., the newest version of the results are returned), and correct (i.e., the result values are not corrupted). In this paper, we identify a specific scenario in which classical techniques for query integrity appear little suitable and we propose a new solution to overcome these drawbacks. The scenario considered, instantiated in a realistic video surveillance setting, is that of data streams in which append operations and range queries are dominant, and the efficiency is a critical factor.