Spammers are continually looking to circumvent counter-measures seeking to slow them down. An immense amount of time and money is currently devoted to hiding spam, but not enough is devoted to effectively preventing it. One approach for preventing spam is to force the spammer's machine to solve a computational problem of varying difficulty before granting access. The idea is that suspicious or problematic requests are given difficult problems to solve while legitimate requests are allowed through with minimal computation. Unfortunately, most systems that employ this model waste the computing resources being used, as they are directed towards solving cryptographic problems that provide no societal benefit. While systems such as reCAPTCHA and FoldIt have allowed users to contribute solutions to useful problems interactively, an analogous solution for non-interactive proof-of-work does not exist. Towards this end, this paper describes MetaCAPTCHA and reBOINC, an infrastructure for supporting useful proof-of-work that is integrated into a web spam throttling service. The infrastructure dynamically issues CAPTCHAs and proof-of-work puzzles while ensuring that malicious users solve challenging puzzles. Additionally, it provides a framework that enables the computational resources of spammers to be redirected towards meaningful research. To validate the efficacy of our approach, prototype implementations based on OpenCV and BOINC are described that demonstrate the ability to harvest spammer's resources for beneficial purposes.

This study examines the conditions for successful online mentoring in order to develop writing skills in English in a workplace setting. Chapter 1 gives the background and context of the study. Problems to be addressed in the study and the aims, objectives, hypotheses and their rationale are presented. This is followed by testing procedures, research design, sources of data and research procedures. In Chapter 2, the literature review supports the hypotheses on the need for collaboration in materials development and delivery, mentoring relationships, motivation and computer and Internet efficacy. Chapter 3 presents the findings from the case study bringing into focus problems that would jeopardise a mentoring programme if training providers do not pay attention to the hypotheses. The findings are collated and the hypotheses are confirmed. Conditions for successful online mentoring are spelt out in Chapter 4. The study concludes that online mentoring works once the conditions are properly followed. / English Studies / M.A. (TESOL)

Thesis (LLM)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The monitoring of electronic communication is likely to face all employers sooner or later. The rapid advancement in technology aimed at helping to monitor electronic communication, makes it easier than ever before for employers to monitor the electronic communications of their employees. There are important questions to consider when dealing with the topic of monitoring electronic communication. Examples include "mayan employer legally monitor electronic communications?" and "how does monitoring affect the employee's right to privacy?" This thesis is an attempt to answer these and other related questions by analysing, inter alia, South African legislation, the Constitution and case law, as well as comparing the law as it applies in the United Kingdom and the United States of America. The analysis and conclusion offered in this thesis aim to provide theoretical consideration to academics and practical application for employers that are faced with the reality of monitoring electronic communications. / AFRIKAANSE OPSOMMING: Alle werkgewers sal waarskynlik die een of ander tyd met die monitering van elektroniese kommunikasie gekonfronteer word. Die snelle voortuitgang in tegnologie wat daarop gemik is om te help met die monitering van elektroniese kommunikasie, maak dit vir werkgewers makliker as ooit tevore om sodanige kommunikasies van hulle werknemers te monitor. Daar is egter belangrike vrae wat oorweeg moet word wanneer die onderwerp van monitering van elektroniese kommunikasie ter sprake kom. Voorbeelde hiervan is "mag 'n werknemer regtens elektroniese kommunikasies monitor?" en "hoe raak monitering die werknemer se reg tot privaatheid?" Hierdie tesis is 'n poging om hierdie en ander verwante vrae te beantwoord deur die ontleding van, onder andere, Suid-Afrikaanse wetgewing, die Grondwet en die reg soos deur hofuitsprake ontwikkel, sowel as vergelyking van die reg soos wat dit van toepassing is in die Verenigde Koninkryk en die Verenigde State van Amerika. Die ontleding en gevolgtrekking wat in hierdie tesis aangebied word, is gemik op die verskaffing van teoretiese oorweging aan akademici en praktiese toepassing vir werkgewers wat met die realiteit van die monitering van elektroniese kommunikasies gekonfronteer word.

A nutrition education program for employed women on maintaining a healthy weight was developed and evaluated. Delivery of eight messages (two per week for four weeks) by electronic mail was tested for effectiveness. The subjects were 243 members of the Oregon State University Office and Personnel Association who were randomly assigned to three experimental groups. Group #1 received hard copies of the messages, group #2 received hard copies along with a weekly electronic tip on weight management, and group #3 received the messages by electronic mail (e-mail). An evaluation survey was developed to assess: 1) Participants' stage of change regarding fat in the diet, 2) Participants' social support network for weight maintenance, 3) Reactions to the program, 4) Impact of the program on positive behavior regarding weight control, and 5) Demographics. The survey was sent by campus mail about three weeks after the program. The evaluation was completed by 80.2% of participants. The nine male respondents and the two gender-unidentified respondents were not included in the data analysis to assure a total female population. A total of 181 surveys were analyzed (74.5%). The mean age of female respondents was 47.8 ± 13.3. Although it was hypothesized that electronic delivery of the program and/or supplementing the hard copy/print program with brief electronic tips would be associated with higher order stages of change (Transtheoretical Model), the results from this study did not support the hypotheses. There was no significant difference in stage of change among participants in the three modes of delivery. The messages appeared to have the greatest impact on women in the action and preparation stages. They tended to make more positive changes (i.e. reading food labels) than women in the maintenance, contemplation, and precontemplation stages. Mode of delivery did not appear to make a difference in whether the women looked forward to the messages, reactions to message length, how many were read, or the resulting knowledge or behavior change. Therefore, it may not be critical to program effectiveness. Women in the electronic group, however, were more certain that they received all eight messages and were more apt to ask questions of the researcher. The potential cost savings, convenience, and ease of quick communication make it a more attractive option. Access to the technology and participant preference are equally important factors. / Graduation date: 1997

Electronic mail, email, is one of the most widespread computer applications today.While email in general is very popular among its users, there are also drawbacks withemail usage: an increasing amount of messages that overwhelm users, systems that aretoo complex for naive users and at the same time do not support the needs of experiencedusers.In order to answer the main research question “Which design solutions couldimprove the situation of individual email users in a working context when it comes tocommunication and handling large numbers of incoming and stored email messages?”three studies conducted in email users’ working environment are described. The studiedorganisations are one academic research laboratory, one technical company, andone primary medical service organisation. The studies are focused on email usage,organisation of email messages, novice versus experienced users’ needs, managers’email usage, and information and communication overflow.The results indicate that the different strategies used to handle email are a matter ofa balance between advantages and disadvantages of these strategies. The choicebetween them is depending on the users’ total work situation and cannot be understoodby investigating the email communication alone.One advantage of email is the cognitive comfort it brings to its users by liberatingthem from thinking about tasks that can be solved by sending an email message, butthis advantage disappears when the sender cannot trust that the receiver will act uponthe message.Users develop their handling of email with experience and work position. Themedia that managers use to handle the increased communication that follows with ahigher position are email and meetings. One habit that do not change with position isto allow incoming messages to interrupt other work tasks, despite the asynchronousnature of email. This is particularly remarkable for managers who often complain thatthey need more uninterrupted time. The interruptions may partly be attributed to thelack of functionality in email systems to adapt the interfaces to the users’ work habits.In this case incoming messages result in a signal regardless the importance of them.Email is a part of an information and communication flow. Some users have problemshandling this flow. Overflow problems could be diminished by making senders ofmessages more aware of the receivers’ communicative situation. Email systems couldprovide feedback to senders of messages based on the receivers’ perception of his/hersituation.One of the studies indicates that it may be even more complicated to replace an oldemail system than introducing an email system for the first time in an organisation.The investment experienced users have made in the old system may be substantial.A model of time usage for organisation of email messages is also presented in orderto compare different strategies.Several design solutions are suggested with respect to folder usage, sorting emailmessages into folders, reducing the number of stored messages, and tailoring the emailsystem to the user’s work habits. / QC 20100524

Universiẗat, Diss.--Freiburg. i. Br., 2005. / Literaturverz. S. 274 - 285.

M. Tech. Business Information Systems / Although owners of Internet cafés extend the freedom to have Internet access to the community, they fail to tighten their computer security to safeguard the private information of their customers. This dissertation provides a conceptual framework for improving information security in the Internet Café, to help and ensure data privacy, data integrity, risk management and information security (IS) behaviour. The study investigated the information security issues that are faced by users of Internet cafés and explored the effects of these issues. The framework shows how users can improve their physical security to reach higher standards of information privacy over the Internet.

published_or_final_version / Education / Master / Master of Education

The advent of the Internet has generated a proliferation of online information-rich environments, which provide information consumers with an unprecedented amount of freely available information. However, the openness of these environments has also made them vulnerable to a new class of attacks called Denial of Information (DoI) attacks. Attackers launch these attacks by deliberately inserting low quality information into information-rich environments to promote that information or to deny access to high quality information. These attacks directly threaten the usefulness and dependability of online information-rich environments, and as a result, an important research question is how to automatically identify and remove this low quality information from these environments. The first contribution of this thesis research is a set of techniques for automatically recognizing and countering various forms of DoI attacks in email systems. We develop a new DoI attack based on camouflaged messages, and we show that spam producers and information consumers are entrenched in a spam arms race. To break free of this arms race, we propose two solutions. One solution involves refining the statistical learning process by associating disproportionate weights to spam and legitimate features, and the other solution leverages the existence of non-textual email features (e.g., URLs) to make the classification process more resilient against attacks. The second contribution of this thesis is a framework for collecting, analyzing, and classifying examples of DoI attacks in the World Wide Web. We propose a fully automatic Web spam collection technique and use it to create the Webb Spam Corpus -- a first-of-its-kind, large-scale, and publicly available Web spam data set. Then, we perform the first large-scale characterization of Web spam using content and HTTP session analysis. Next, we present a lightweight, predictive approach to Web spam classification that relies exclusively on HTTP session information. The final contribution of this thesis research is a collection of techniques that detect and help prevent DoI attacks within social environments. First, we provide detailed descriptions for each of these attacks. Then, we propose a novel technique for capturing examples of social spam, and we use our collected data to perform the first characterization of social spammers and their behaviors.

Thesis (doctoral)--Albert-Ludwigs-Universität Freiburg im Breisgau, 2007. / Includes bibliographical references (p. 271-284).