Introduction
Definition
Types
Issues
Study based on BDF
Evaluation
Conclusion
INTRODUCTION
Internet is becoming an integral part of our everyday life. Most data are stored and retrieved from time to time over the network across organizations, even across the world.
Web services designed to be used by humans are abused by automated computer programs that pose as humans and perform malicious activities.
CAPTCHA, Completely Automated public Turing test to tell Computers and Humans Apart.
CAPTCHA is a standard security technology for distinguish between human and computer program automatically.
Definition
Types
Issues
Study based on BDF
Evaluation
Conclusion
INTRODUCTION
Internet is becoming an integral part of our everyday life. Most data are stored and retrieved from time to time over the network across organizations, even across the world.
Web services designed to be used by humans are abused by automated computer programs that pose as humans and perform malicious activities.
CAPTCHA, Completely Automated public Turing test to tell Computers and Humans Apart.
CAPTCHA is a standard security technology for distinguish between human and computer program automatically.
CAPTCHA
The fundamental problem of using password is that the login password was hacked by malicious software and the password was uncovered.
CAPTCHA Completely Automated Public Turing tests to tell Computers and Humans Apart.
Common technique that insists users to enter a set of text before entering to the system was proposed by Luis Von Ahn
CAPTCHA is a program implemented for distinguishing between human and automate computer programs by generating questions that can be answered by mankind only.
A CAPTCHA ensures that a real person is attempting to log in, and not a computer trying random strings.
There are registration forms on many websites which users should fill out them to be able to use website services. Unfortunately some vandalistic persons write programs which are filling out the registration forms with incorrect information automatically.
TYPES OF CAPTCHAs
Text based captcha
Graphic based captcha
Audio based captcha
Text based captcha
CAPTCHA style looks simple, easy and most popular.
Created by a computer program by random selecting a sequence of letters, rendering them, distorting the image, and adding noise.
Graphic based captcha
Not suitable for persons who have ability of thinking or interpreting the image to answer questions.
Audio based captcha
This technique is developed for a specific group who has eye vision problem.
Objective of the sound-based CAPTCHA is developed to serve blind persons so they can equally use a secure computer.
The system will pronounce the letter and the blind person must press the right keyboard according to the hearing vocal.
Multi-Modal CAPTCHA
image is being rendered on the screen and many text labels drawn over it.
