14-03-2010, 09:09 PM
ppl can u please help abt the topic for the seminar..
I needed a ppt or a pdf for the same..
Thanks
14-03-2010, 09:09 PM
ppl can u please help abt the topic for the seminar.. I needed a ppt or a pdf for the same.. Thanks
18-03-2010, 06:01 PM
12-03-2011, 09:57 PM
ppl can u please help abt the topic for the seminar..
I needed a ppt or a pdf for the same..(CAPTCHA)
13-03-2011, 12:34 PM
Hi,
visit these threads for reports and ppt on captcha: https://seminarproject.net/Thread-c-a-p-...-humans-ap https://seminarproject.net/Thread-captch...9#pid29279 http://project-seminars.com/attachment.php?aid=8574
26-05-2012, 01:19 PM
CAPTCHA
CAPTCHA.ppt (Size: 661 KB / Downloads: 54) Definition CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart The challenge: develop a software program that can create and grade tests, that humans can pass but current computer programs cannot. Background The term CAPTCHA was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas Hopper and John Langford of Carnegie Mellon University. At the time, they developed the first CAPTCHA to be used by Yahoo First used by Altavista in1997 Reduced SPAM add-url by over 95% CMU/Yahoo! Automated the creating and grading of challenges PARC Relies on document image degradation to prevent successful OCR Conducted user-focused studies to assess the effectiveness of CAPTCHAs Motivation The general motivation for decoding CAPTCHAs is financial gain e.g. through spamming, spreading viruses. However, another motivation for decoding CAPTCHAs is improvement of Object Character Recognition. Free Emil Services Several companies (Yahoo!, Microsoft, etc.) offer free email services. Up until a few years ago, most of these services suffered from a specific type of attack: "bots" that would sign up for thousands of email accounts every minute. The solution to this problem was to use CAPTCHAs to ensure that only humans obtain free accounts. In general, free services should be protected with a CAPTCHA in order to prevent abuse by automated programs. Audio Based CAPTCHAs Pick a word or a sequence of numbers at random Reenter them into an audio clip using a TTS software Distort the audio clip Ask the user to identify and type the word or numbers
24-09-2012, 11:04 AM
CAPTCHA
captcha report.doc (Size: 508 KB / Downloads: 25) INTRODUCTION A program that can tell whether its user is a human or a computer. A captcha is a type of challenge-response test used in computing to ensure that the response is not generated by a computer. The process usually involves one computer (a server) asking a user to complete a simple test which the computer is able to generate and grade. Because other computers are assumed to be unable to solve the CAPTCHA, any user entering a correct solution is presumed to be human. A CAPTCHA is a means of automatically generating challenges which intends to: Provide a problem easy enough for all humans to solve. Prevent standard automated software from filling out a form HISTORY One common application of CAPTCHA is for verifying online poll. In fact, a former Slashdot poll serves as an example of what can go wrong if pollsters don't implement filters on their surveys. In 1999, Slashdot published a poll that asked visitors to choose the graduate school that had the best program in computer science. Students from two universities -- Carnegie Mellon and MIT -- created automated programs called bots to vote repeatedly for their respective schools. While those two schools received thousands of votes, the other schools only had a few hundred each. If it's possible to create a program that can vote in a poll, how can we trust online poll results at all? A CAPTCHA form can help prevent programmers from taking advantage of the polling system. 3D IMAGES AS A CAPTCHA In the below illustration you will see that I have created a CAPTCHA interface that asks a user to verify that the top image matches one of the bottom images. A user can do this with ease, while a computer would be totally confounded by the randomly rotated view of the objects. And this is the crux of the design. APPLICATIONS CAPTCHAs have several applications for practical security, including (but not limited to): • Preventing Comment Spam in Blogs. Most bloggers are familiar with programs that submit bogus comments, usually for the purpose of raising search engine ranks of some website (e.g., "buy penny stocks here"). This is called comment spam. By using a CAPTCHA, only humans can enter comments on a blog. There is no need to make users sign up before they enter a comment, and no legitimate comments are ever lost! • Protecting Website Registration. Several companies (Yahoo!, Microsoft, etc.) offer free email services. Up until a few years ago, most of these services suffered from a specific type of attack: "bots" that would sign up for thousands of email accounts every minute. The solution to this problem was to use CAPTCHAs to ensure that only humans obtain free accounts. In general, free services should be protected with a CAPTCHA in order to prevent abuse by automated programs. |
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