Visible to the public Biblio

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2020-05-26
Ostrovskaya, Svetlana, Surnin, Oleg, Hussain, Rasheed, Bouk, Safdar Hussain, Lee, JooYoung, Mehran, Narges, Ahmed, Syed Hassan, Benslimane, Abderrahim.  2018.  Towards Multi-metric Cache Replacement Policies in Vehicular Named Data Networks. 2018 IEEE 29th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC). :1–7.
Vehicular Named Data Network (VNDN) uses NDN as an underlying communication paradigm to realize intelligent transportation system applications. Content communication is the essence of NDN, which is primarily carried out through content naming, forwarding, intrinsic content security, and most importantly the in-network caching. In vehicular networks, vehicles on the road communicate with other vehicles and/or infrastructure network elements to provide passengers a reliable, efficient, and infotainment-rich commute experience. Recently, different aspects of NDN have been investigated in vehicular networks and in vehicular social networks (VSN); however, in this paper, we investigate the in-network caching, realized in NDN through the content store (CS) data structure. As the stale contents in CS do not just occupy cache space, but also decrease the overall performance of NDN-driven VANET and VSN applications, therefore the size of CS and the content lifetime in CS are primary issues in VNDN communications. To solve these issues, we propose a simple yet efficient multi-metric CS management mechanism through cache replacement (M2CRP). We consider the content popularity, relevance, freshness, and distance of a node to devise a set of algorithms for selection of the content to be replaced in CS in the case of replacement requirement. Simulation results show that our multi-metric strategy outperforms the existing cache replacement mechanisms in terms of Hit Ratio.
2020-05-08
Huang, Yifan, Chung, Wingyan, Tang, Xinlin.  2018.  A Temporal Recurrent Neural Network Approach to Detecting Market Anomaly Attacks. 2018 IEEE International Conference on Intelligence and Security Informatics (ISI). :160—162.
In recent years, the spreading of malicious social media messages about financial stocks has threatened the security of financial market. Market Anomaly Attacks is an illegal practice in the stock or commodities markets that induces investors to make purchase or sale decisions based on false information. Identifying these threats from noisy social media datasets remains challenging because of the long time sequence in these social media postings, ambiguous textual context and the difficulties for traditional deep learning approaches to handle both temporal and text dependent data such as financial social media messages. This research developed a temporal recurrent neural network (TRNN) approach to capturing both time and text sequence dependencies for intelligent detection of market anomalies. We tested the approach by using financial social media of U.S. technology companies and their stock returns. Compared with traditional neural network approaches, TRNN was found to more efficiently and effectively classify abnormal returns.
2020-04-20
Raber, Frederic, Krüger, Antonio.  2018.  Deriving Privacy Settings for Location Sharing: Are Context Factors Always the Best Choice? 2018 IEEE Symposium on Privacy-Aware Computing (PAC). :86–94.
Research has observed context factors like occasion and time as influential factors for predicting whether or not to share a location with online friends. In other domains like social networks, personality was also found to play an important role. Furthermore, users are seeking a fine-grained disclosement policy that also allows them to display an obfuscated location, like the center of the current city, to some of their friends. In this paper, we observe which context factors and personality measures can be used to predict the correct privacy level out of seven privacy levels, which include obfuscation levels like center of the street or current city. Our results show that a prediction is possible with a precision 20% better than a constant value. We will give design indications to determine which context factors should be recorded, and how much the precision can be increased if personality and privacy measures are recorded using either a questionnaire or automated text analysis.
Raber, Frederic, Krüger, Antonio.  2018.  Deriving Privacy Settings for Location Sharing: Are Context Factors Always the Best Choice? 2018 IEEE Symposium on Privacy-Aware Computing (PAC). :86–94.
Research has observed context factors like occasion and time as influential factors for predicting whether or not to share a location with online friends. In other domains like social networks, personality was also found to play an important role. Furthermore, users are seeking a fine-grained disclosement policy that also allows them to display an obfuscated location, like the center of the current city, to some of their friends. In this paper, we observe which context factors and personality measures can be used to predict the correct privacy level out of seven privacy levels, which include obfuscation levels like center of the street or current city. Our results show that a prediction is possible with a precision 20% better than a constant value. We will give design indications to determine which context factors should be recorded, and how much the precision can be increased if personality and privacy measures are recorded using either a questionnaire or automated text analysis.
2020-04-13
Horne, Benjamin D., Gruppi, Mauricio, Adali, Sibel.  2019.  Trustworthy Misinformation Mitigation with Soft Information Nudging. 2019 First IEEE International Conference on Trust, Privacy and Security in Intelligent Systems and Applications (TPS-ISA). :245–254.
Research in combating misinformation reports many negative results: facts may not change minds, especially if they come from sources that are not trusted. Individuals can disregard and justify lies told by trusted sources. This problem is made even worse by social recommendation algorithms which help amplify conspiracy theories and information confirming one's own biases due to companies' efforts to optimize for clicks and watch time over individuals' own values and public good. As a result, more nuanced voices and facts are drowned out by a continuous erosion of trust in better information sources. Most misinformation mitigation techniques assume that discrediting, filtering, or demoting low veracity information will help news consumers make better information decisions. However, these negative results indicate that some news consumers, particularly extreme or conspiracy news consumers will not be helped. We argue that, given this background, technology solutions to combating misinformation should not simply seek facts or discredit bad news sources, but instead use more subtle nudges towards better information consumption. Repeated exposure to such nudges can help promote trust in better information sources and also improve societal outcomes in the long run. In this article, we will talk about technological solutions that can help us in developing such an approach, and introduce one such model called Trust Nudging.
2020-03-23
Hu, Rui, Guo, Yuanxiong, Pan, Miao, Gong, Yanmin.  2019.  Targeted Poisoning Attacks on Social Recommender Systems. 2019 IEEE Global Communications Conference (GLOBECOM). :1–6.
With the popularity of online social networks, social recommendations that rely on one’s social connections to make personalized recommendations have become possible. This introduces vulnerabilities for an adversarial party to compromise the recommendations for users by utilizing their social connections. In this paper, we propose the targeted poisoning attack on the factorization-based social recommender system in which the attacker aims to promote an item to a group of target users by injecting fake ratings and social connections. We formulate the optimal poisoning attack as a bi-level program and develop an efficient algorithm to find the optimal attacking strategy. We then evaluate the proposed attacking strategy on real-world dataset and demonstrate that the social recommender system is sensitive to the targeted poisoning attack. We find that users in the social recommender system can be attacked even if they do not have direct social connections with the attacker.
2020-03-18
Van, Hao, Nguyen, Huyen N., Hewett, Rattikorn, Dang, Tommy.  2019.  HackerNets: Visualizing Media Conversations on Internet of Things, Big Data, and Cybersecurity. 2019 IEEE International Conference on Big Data (Big Data). :3293–3302.
The giant network of Internet of Things establishes connections between smart devices and people, with protocols to collect and share data. While the data is expanding at a fast pace in this era of Big Data, there are growing concerns about security and privacy policies. In the current Internet of Things ecosystems, at the intersection of the Internet of Things, Big Data, and Cybersecurity lies the subject that attracts the most attention. In aiding users in getting an adequate understanding, this paper introduces HackerNets, an interactive visualization for emerging topics in the crossing of IoT, Big Data, and Cybersecurity over time. To demonstrate the effectiveness and usefulness of HackerNets, we apply and evaluate the technique on the dataset from the social media platform.
2020-02-10
Chen, Siyuan, Liu, Wei, Liu, Jiamou, Soo, Khí-Uí, Chen, Wu.  2019.  Maximizing Social Welfare in Fractional Hedonic Games using Shapley Value. 2019 IEEE International Conference on Agents (ICA). :21–26.
Fractional hedonic games (FHGs) are extensively studied in game theory and explain the formation of coalitions among individuals in a group. This paper investigates the coalition generation problem, namely, finding a coalition structure whose social welfare, i.e., the sum of the players' payoffs, is maximized. We focus on agent-based methods which set the decision rules for each player in the game. Through repeated interactions the players arrive at a coalition structure. In particular, we propose CFSV, namely, coalition formation with Shapley value-based welfare distribution scheme. To evaluate CFSV, we theoretically demonstrate that this algorithm achieves optimal coalition structure over certain standard graph classes and empirically compare the algorithm against other existing benchmarks on real-world and synthetic graphs. The results show that CFSV is able to achieve superior performance.
Elakkiya, E, Selvakumar, S.  2019.  Initial Weights Optimization Using Enhanced Step Size Firefly Algorithm for Feed Forward Neural Network Applied to Spam Detection. TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON). :942–946.

Spams are unsolicited and unnecessary messages which may contain harmful codes or links for activation of malicious viruses and spywares. Increasing popularity of social networks attracts the spammers to perform malicious activities in social networks. So an efficient spam detection method is necessary for social networks. In this paper, feed forward neural network with back propagation based spam detection model is proposed. The quality of the learning process is improved by tuning initial weights of feed forward neural network using proposed enhanced step size firefly algorithm which reduces the time for finding optimal weights during the learning process. The model is applied for twitter dataset and the experimental results show that, the proposed model performs well in terms of accuracy and detection rate and has lower false positive rate. 

2020-01-27
Pascucci, Antonio, Masucci, Vincenzo, Monti, Johanna.  2019.  Computational Stylometry and Machine Learning for Gender and Age Detection in Cyberbullying Texts. 2019 8th International Conference on Affective Computing and Intelligent Interaction Workshops and Demos (ACIIW). :1–6.

The aim of this paper is to show the importance of Computational Stylometry (CS) and Machine Learning (ML) support in author's gender and age detection in cyberbullying texts. We developed a cyberbullying detection platform and we show the results of performances in terms of Precision, Recall and F -Measure for gender and age detection in cyberbullying texts we collected.

2019-12-09
Gao, Yali, Li, Xiaoyong, Li, Jirui, Gao, Yunquan, Yu, Philip S..  2019.  Info-Trust: A Multi-Criteria and Adaptive Trustworthiness Calculation Mechanism for Information Sources. IEEE Access. 7:13999–14012.
Social media have become increasingly popular for the sharing and spreading of user-generated content due to their easy access, fast dissemination, and low cost. Meanwhile, social media also enable the wide propagation of cyber frauds, which leverage fake information sources to reach an ulterior goal. The prevalence of untrustworthy information sources on social media can have significant negative societal effects. In a trustworthy social media system, trust calculation technology has become a key demand for the identification of information sources. Trust, as one of the most complex concepts in network communities, has multi-criteria properties. However, the existing work only focuses on single trust factor, and does not consider the complexity of trust relationships in social computing completely. In this paper, a multi-criteria trustworthiness calculation mechanism called Info-Trust is proposed for information sources, in which identity-based trust, behavior-based trust, relation-based trust, and feedback-based trust factors are incorporated to present an accuracy-enhanced full view of trustworthiness evaluation of information sources. More importantly, the weights of these factors are dynamically assigned by the ordered weighted averaging and weighted moving average (OWA-WMA) combination algorithm. This mechanism surpasses the limitations of existing approaches in which the weights are assigned subjectively. The experimental results based on the real-world datasets from Sina Weibo demonstrate that the proposed mechanism achieves greater accuracy and adaptability in trustworthiness identification of the network information.
2019-10-15
Pan, Y., He, F., Yu, H..  2018.  An Adaptive Method to Learn Directive Trust Strength for Trust-Aware Recommender Systems. 2018 IEEE 22nd International Conference on Computer Supported Cooperative Work in Design ((CSCWD)). :10–16.

Trust Relationships have shown great potential to improve recommendation quality, especially for cold start and sparse users. Since each user trust their friends in different degrees, there are numbers of works been proposed to take Trust Strength into account for recommender systems. However, these methods ignore the information of trust directions between users. In this paper, we propose a novel method to adaptively learn directive trust strength to improve trust-aware recommender systems. Advancing previous works, we propose to establish direction of trust strength by modeling the implicit relationships between users with roles of trusters and trustees. Specially, under new trust strength with directions, how to compute the directive trust strength is becoming a new challenge. Therefore, we present a novel method to adaptively learn directive trust strengths in a unified framework by enforcing the trust strength into range of [0, 1] through a mapping function. Our experiments on Epinions and Ciao datasets demonstrate that the proposed algorithm can effectively outperform several state-of-art algorithms on both MAE and RMSE metrics.

2019-06-10
Kim, H. M., Song, H. M., Seo, J. W., Kim, H. K..  2018.  Andro-Simnet: Android Malware Family Classification Using Social Network Analysis. 2018 16th Annual Conference on Privacy, Security and Trust (PST). :1-8.

While the rapid adaptation of mobile devices changes our daily life more conveniently, the threat derived from malware is also increased. There are lots of research to detect malware to protect mobile devices, but most of them adopt only signature-based malware detection method that can be easily bypassed by polymorphic and metamorphic malware. To detect malware and its variants, it is essential to adopt behavior-based detection for efficient malware classification. This paper presents a system that classifies malware by using common behavioral characteristics along with malware families. We measure the similarity between malware families with carefully chosen features commonly appeared in the same family. With the proposed similarity measure, we can classify malware by malware's attack behavior pattern and tactical characteristics. Also, we apply community detection algorithm to increase the modularity within each malware family network aggregation. To maintain high classification accuracy, we propose a process to derive the optimal weights of the selected features in the proposed similarity measure. During this process, we find out which features are significant for representing the similarity between malware samples. Finally, we provide an intuitive graph visualization of malware samples which is helpful to understand the distribution and likeness of the malware networks. In the experiment, the proposed system achieved 97% accuracy for malware classification and 95% accuracy for prediction by K-fold cross-validation using the real malware dataset.

2019-02-18
Shamieh, F., Alharbi, R..  2018.  Novel Sybil Defense Scheme for Peer–to–peer Applications. 2018 21st Saudi Computer Society National Computer Conference (NCC). :1–8.

The importance of peer-to-peer (P2P) network overlays produced enormous interest in the research community due to their robustness, scalability, and increase of data availability. P2P networks are overlays of logically connected hosts and other nodes including servers. P2P networks allow users to share their files without the need for any centralized servers. Since P2P networks are largely constructed of end-hosts, they are susceptible to abuse and malicious activity, such as sybil attacks. Impostors perform sybil attacks by assigning nodes multiple addresses, as opposed to a single address, with the goal of degrading network quality. Sybil nodes will spread malicious data and provide bogus responses to requests. To prevent sybil attacks from occurring, a novel defense mechanism is proposed. In the proposed scheme, the DHT key-space is divided and treated in a similar manner to radio frequency allocation incensing. An overlay of trusted nodes is used to detect and handle sybil nodes with the aid of source-destination pairs reporting on each other. The simulation results show that the proposed scheme detects sybil nodes in large sized networks with thousands of interactions.

2019-01-31
Chen, Y., Wu, B..  2018.  An Efficient Algorithm for Minimal Edit Cost of Graph Degree Anonymity. 2018 IEEE International Conference on Applied System Invention (ICASI). :574–577.

Personal privacy is an important issue when publishing social network data. An attacker may have information to reidentify private data. So, many researchers developed anonymization techniques, such as k-anonymity, k-isomorphism, l-diversity, etc. In this paper, we focus on graph k-degree anonymity by editing edges. Our method is divided into two steps. First, we propose an efficient algorithm to find a new degree sequence with theoretically minimal edit cost. Second, we insert and delete edges based on the new degree sequence to achieve k-degree anonymity.

2018-09-28
Hu, J., Shi, W., Liu, H., Yan, J., Tian, Y., Wu, Z..  2017.  Preserving Friendly-Correlations in Uncertain Graphs Using Differential Privacy. 2017 International Conference on Networking and Network Applications (NaNA). :24–29.

It is a challenging problem to preserve the friendly-correlations between individuals when publishing social-network data. To alleviate this problem, uncertain graph has been presented recently. The main idea of uncertain graph is converting an original graph into an uncertain form, where the correlations between individuals is an associated probability. However, the existing methods of uncertain graph lack rigorous guarantees of privacy and rely on the assumption of adversary's knowledge. In this paper we first introduced a general model for constructing uncertain graphs. Then, we proposed an algorithm under the model which is based on differential privacy and made an analysis of algorithm's privacy. Our algorithm provides rigorous guarantees of privacy and against the background knowledge attack. Finally, the algorithm we proposed satisfied differential privacy and showed feasibility in the experiments. And then, we compare our algorithm with (k, ε)-obfuscation algorithm in terms of data utility, the importance of nodes for network in our algorithm is similar to (k, ε)-obfuscation algorithm.

2018-08-23
Nizamkari, N. S..  2017.  A graph-based trust-enhanced recommender system for service selection in IOT. 2017 International Conference on Inventive Systems and Control (ICISC). :1–5.

In an Internet of Things (IOT) network, each node (device) provides and requires services and with the growth in IOT, the number of nodes providing the same service have also increased, thus creating a problem of selecting one reliable service from among many providers. In this paper, we propose a scalable graph-based collaborative filtering recommendation algorithm, improved using trust to solve service selection problem, which can scale to match the growth in IOT unlike a central recommender which fails. Using this recommender, a node can predict its ratings for the nodes that are providing the required service and then select the best rated service provider.

Xi, X., Zhang, F., Lian, Z..  2017.  Implicit Trust Relation Extraction Based on Hellinger Distance. 2017 13th International Conference on Semantics, Knowledge and Grids (SKG). :223–227.

Recent studies have shown that adding explicit social trust information to social recommendation significantly improves the prediction accuracy of ratings, but it is difficult to obtain a clear trust data among users in real life. Scholars have studied and proposed some trust measure methods to calculate and predict the interaction and trust between users. In this article, a method of social trust relationship extraction based on hellinger distance is proposed, and user similarity is calculated by describing the f-divergence of one side node in user-item bipartite networks. Then, a new matrix factorization model based on implicit social relationship is proposed by adding the extracted implicit social relations into the improved matrix factorization. The experimental results support that the effect of using implicit social trust to recommend is almost the same as that of using actual explicit user trust ratings, and when the explicit trust data cannot be extracted, our method has a better effect than the other traditional algorithms.

2018-06-20
Kulkarni, S., Sawihalli, A., Ambika, R., Naik, L..  2017.  Mobile powered sub-group detection/formation using taste-based collaborative filtering technique. 2017 Innovations in Power and Advanced Computing Technologies (i-PACT). :1–5.

Social networking sites such as Flickr, YouTube, Facebook, etc. contain huge amount of user contributed data for a variety of real-world events. We describe an unsupervised approach to the problem of automatically detecting subgroups of people holding similar tastes or either taste. Item or taste tags play an important role in detecting group or subgroup, if two or more persons share the same opinion on the item or taste, they tend to use similar content. We consider the latter to be an implicit attitude. In this paper, we have investigated the impact of implicit and explicit attitude in two genres of social media discussion data, more formal wikipedia discussions and a debate discussion forum that is much more informal. Experimental results strongly suggest that implicit attitude is an important complement for explicit attitudes (expressed via sentiment) and it can improve the sub-group detection performance independent of genre. Here, we have proposed taste-based group, which can enhance the quality of service.

2018-02-06
Li, X., Smith, J. D., Thai, M. T..  2017.  Adaptive Reconnaissance Attacks with Near-Optimal Parallel Batching. 2017 IEEE 37th International Conference on Distributed Computing Systems (ICDCS). :699–709.

In assessing privacy on online social networks, it is important to investigate their vulnerability to reconnaissance strategies, in which attackers lure targets into being their friends by exploiting the social graph in order to extract victims' sensitive information. As the network topology is only partially revealed after each successful friend request, attackers need to employ an adaptive strategy. Existing work only considered a simple strategy in which attackers sequentially acquire one friend at a time, which causes tremendous delay in waiting for responses before sending the next request, and which lack the ability to retry failed requests after the network has changed. In contrast, we investigate an adaptive and parallel strategy, of which attackers can simultaneously send multiple friend requests in batch and recover from failed requests by retrying after topology changes, thereby significantly reducing the time to reach the targets and greatly improving robustness. We cast this approach as an optimization problem, Max-Crawling, and show it inapproximable within (1 - 1/e + $ε$). We first design our core algorithm PM-AReST which has an approximation ratio of (1 - e-(1-1/e)) using adaptive monotonic submodular properties. We next tighten our algorithm to provide a nearoptimal solution, i.e. having a ratio of (1 - 1/e), via a two-stage stochastic programming approach. We further establish the gap bound of (1 - e-(1-1/e)2) between batch strategies versus the optimal sequential one. We experimentally validate our theoretical results, finding that our algorithm performs nearoptimally in practice and that this is robust under a variety of problem settings.

Marciani, G., Porretta, M., Nardelli, M., Italiano, G. F..  2017.  A Data Streaming Approach to Link Mining in Criminal Networks. 2017 5th International Conference on Future Internet of Things and Cloud Workshops (FiCloudW). :138–143.

The ability to discover patterns of interest in criminal networks can support and ease the investigation tasks by security and law enforcement agencies. By considering criminal networks as a special case of social networks, we can properly reuse most of the state-of-the-art techniques to discover patterns of interests, i.e., hidden and potential links. Nevertheless, in time-sensible scenarios, like the one involving criminal actions, the ability to discover patterns in a (near) real-time manner can be of primary importance.In this paper, we investigate the identification of patterns for link detection and prediction on an evolving criminal network. To extract valuable information as soon as data is generated, we exploit a stream processing approach. To this end, we also propose three new similarity social network metrics, specifically tailored for criminal link detection and prediction. Then, we develop a flexible data stream processing application relying on the Apache Flink framework; this solution allows us to deploy and evaluate the newly proposed metrics as well as the ones existing in literature. The experimental results show that the new metrics we propose can reach up to 83% accuracy in detection and 82% accuracy in prediction, resulting competitive with the state of the art metrics.

Zhang, Y., Mao, W., Zeng, D..  2017.  Topic Evolution Modeling in Social Media Short Texts Based on Recurrent Semantic Dependent CRP. 2017 IEEE International Conference on Intelligence and Security Informatics (ISI). :119–124.

Social media has become an important platform for people to express opinions, share information and communicate with others. Detecting and tracking topics from social media can help people grasp essential information and facilitate many security-related applications. As social media texts are usually short, traditional topic evolution models built based on LDA or HDP often suffer from the data sparsity problem. Recently proposed topic evolution models are more suitable for short texts, but they need to manually specify topic number which is fixed during different time period. To address these issues, in this paper, we propose a nonparametric topic evolution model for social media short texts. We first propose the recurrent semantic dependent Chinese restaurant process (rsdCRP), which is a nonparametric process incorporating word embeddings to capture semantic similarity information. Then we combine rsdCRP with word co-occurrence modeling and build our short-text oriented topic evolution model sdTEM. We carry out experimental studies on Twitter dataset. The results demonstrate the effectiveness of our method to monitor social media topic evolution compared to the baseline methods.

Xylogiannopoulos, K., Karampelas, P., Alhajj, R..  2017.  Text Mining in Unclean, Noisy or Scrambled Datasets for Digital Forensics Analytics. 2017 European Intelligence and Security Informatics Conference (EISIC). :76–83.

In our era, most of the communication between people is realized in the form of electronic messages and especially through smart mobile devices. As such, the written text exchanged suffers from bad use of punctuation, misspelling words, continuous chunk of several words without spaces, tables, internet addresses etc. which make traditional text analytics methods difficult or impossible to be applied without serious effort to clean the dataset. Our proposed method in this paper can work in massive noisy and scrambled texts with minimal preprocessing by removing special characters and spaces in order to create a continuous string and detect all the repeated patterns very efficiently using the Longest Expected Repeated Pattern Reduced Suffix Array (LERP-RSA) data structure and a variant of All Repeated Patterns Detection (ARPaD) algorithm. Meta-analyses of the results can further assist a digital forensics investigator to detect important information to the chunk of text analyzed.

2018-01-10
Devyatkin, D., Smirnov, I., Ananyeva, M., Kobozeva, M., Chepovskiy, A., Solovyev, F..  2017.  Exploring linguistic features for extremist texts detection (on the material of Russian-speaking illegal texts). 2017 IEEE International Conference on Intelligence and Security Informatics (ISI). :188–190.

In this paper we present results of a research on automatic extremist text detection. For this purpose an experimental dataset in the Russian language was created. According to the Russian legislation we cannot make it publicly available. We compared various classification methods (multinomial naive Bayes, logistic regression, linear SVM, random forest, and gradient boosting) and evaluated the contribution of differentiating features (lexical, semantic and psycholinguistic) to classification quality. The results of experiments show that psycholinguistic and semantic features are promising for extremist text detection.

2017-12-12
Bijoy, J. M., Kavitha, V. K., Radhakrishnan, B., Suresh, L. P..  2017.  A Graphical Password Authentication for analyzing legitimate user in online social network and secure social image repository with metadata. 2017 International Conference on Circuit ,Power and Computing Technologies (ICCPCT). :1–7.

Internet plays a crucial role in today's life, so the usage of online social network monotonically increasing. People can share multimedia information's fastly and keep in touch or communicate with friend's easily through online social network across the world. Security in authentication is a big challenge in online social network and authentication is a preliminary process for identifying legitimate user. Conventionally, we are using alphanumeric textbased password for authentication approach. But the main flaw points of text based password is highly vulnerable to attacks and difficulty of recalling password during authentication time due to the irregular use of passwords. To overcome the shortcoming of text passwords, we propose a Graphical Password authentication. An approach of Graphical Password is an authentication of amalgam of pictures. It is less vulnerable to attacks and human can easily recall pictures better than text. So the graphical password is a better alternative to text passwords. As the image uploads are increasing by users share through online site, privacy preserving has become a major problem. So we need a Caption Based Metadata Stratification of images for delivers an automatic suggestion of similar category already in database, it works by comparing the caption metadata of album with caption metadata already in database or extract the synonyms of caption metadata of new album for checking the similarity with caption metadata already in database. This stratification offers an enhanced automatic privacy prediction for uploaded images in online social network, privacy is an inevitable factor for uploaded images, and privacy violation is a major concern. So we propose an Automatic Policy Prediction for uploaded images that are classified by caption metadata. An automatic policy prediction is a hassle-free privacy setting proposed to the user.