captcha for presentation

8/9/2019 Captcha for presentation

1/24

CAPTCHA

Presented by:-Sahil SharmaCSE 2nd year


2/24


3/24

AGENDAI. INTRODUCTION

II. DEFINITIONIII. NEED OF CAPTCHA

IV.SPAMS

V. TYPES OF CAPTCHA


4/24

INTRODUCTION

It can generate and grade tests

that humans can pass but current

computer programs cannot.

For example, humans can read

distorted text as shown in thenext slide, but current computer

programs cant .


5/24

SOME EXAMPLES


6/24

ACRONYM

"Completely Automated PublicTuring test to tell Computers andHumans Apart."


7/24

DEFINITION

A CAPTCHA is a type of challenge

response test used in computing to

ensure that response is not

generated by a computer.

It was developed by LUIS VON AHN

and NICOLAS J.HOPPER.


8/24


9/24

Current computer programs

cannot read CAPTCHA.

Current OCRs cannot read them.

It is used by all the accounthandling websites such as g-mail,hotmail,yahoo etc.


10/24

A common type of CAPTCHA requires that

the user type letters or digits from a distorted

image that appears on the screen. The process usually involves one computer

asking a user to complete a simple test which

the computer is able to generate and grade.

Hence it is sometimes also reffered as reverse

TURING test.


11/24

TURINGT

EST

The Turing test is a proposal for a test of a

machine's ability to demonstrate artificial

intelligence. It was proposed by ALAN TURING. Here,judge is a human.

In the participants one is human and other isa computer.


12/24

HUMAN

HUMANCOMPUTER


13/24

PROCEDURE

It proceeds as follows: a human judge engagesin a natural language conversation with one

human and one machine, each of which tries to

appear human. All participants are placed inisolated locations. If the judge cannot reliablytell the machine from the human, the machine is

said to have passed the test.

If computer machine passes this test then it issaid to have some artificial intelligence.


14/24

REVERSE TURING TEST

Reverse turing test is just the opposite of

turing test. it is administered by a machine and targeted

to a human, in contrast to the standard Turing

test that is typically administered by a humanand targeted to a machine


15/24

COMPUTER

COMPUTERHUMAN


16/24

NEED OF CAPTCHA

For stopping the increase of

web e-mail spamsReport abuse

To stop the automatic posting

in blogs.


17/24

SOM

ENUMB

ER

S 8O% of the total e-mails which

are produced in the world aremerely spams.

CAPTCHAhas helped in

decreasing 50% to 60% reductionof spams.


18/24

SPAM

S E-mail spam, known as unsolicited bulk

Email (UBE), is the practice of sending

unwanted e-mail messages toindiscriminate set of recipients.

Also called junk e-mails.

They are produced by some computerexperts called spammers.


19/24

TYPES OF

CAPTCHA


20/24


21/24

GIMPY


22/24

It was initially used byYAHOO.

A dictionary word ispicked at random.

There is no distortionof the text.


23/24

OTHER CAPTCHAS


24/24

THANKYOU

captcha for presentation

Documents