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A new CAPTCHA relocating image layers by exploiting logical thinking

IP.com Disclosure Number: IPCOM000236502D
Publication Date: 2014-Apr-30
Document File: 5 page(s) / 127K

Publishing Venue

The IP.com Prior Art Database

Abstract

This disclosure discloses a CAPTCHA solution for user to easily pass the challenge and still keep the security capability. The solution offers an image composed by two layers. And there will be an obvious logical error or an instruction. With the basic logical thinking, user can perform one drag operation to change the relative position of the two layers to form a new image. The new image will correct the error or follow the instruction, then the test is passed.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 53% of the total text.

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A new CAPTCHA relocating image layers by exploiting logical thinking

CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a method to distinguish human from computer.

Commonly used CAPTCHA methods include:

- String CAPTCHA: System shows an image including characters, and user is asked to input the characters in the image. Distortions, convolutions are added to the text to increase difficulty

- Puzzle CAPTCHA: System shows an image containing a simple question, and user is asked to input the answer. e.g. There are how many balls in the image ?

For String CAPTCHA, distortions, convolutions make it hard for human to recognize the character. And it does not work very well when it is used in touch screen devices: the screen is small and the typo rate is much higher .For Puzzle CAPTCHA, it often asks human to spend more time to pass the test. And meanwhile, advanced computer program can still pass such tests.

Come up with a CAPTCHA that:

Easy to be passed by human, but difficult for computer program


Easy to input in touch screen devices

This disclosure discloses a CAPTCHA solution for user to easily pass the challenge and still keep the security capability. The solution offers an image composed by two layers. And there will be an obvious logical error or an instruction. With the basic logical thinking, user can perform one drag operation to change the relative position of the two layers to form a new image. The new image will correct the error or follow the instruction, then the test is passed.

Advantages:

To pass this kind of CAPTCHA, human users utilize their experiences which accumulated for years, but it will be quite difficult for machine to solve this kind of CAPTCHA, because acquiring and classifying these experiences is not a easy task. And it is also very easy to input the CAPTCHA in touch screen devices: User can pass the CAPTCHA with one only drag operation.

When user is asked to pass the CAPTCHA.

Server side will generate an initial image with two layers. The border of each layer will be marked, so that user can distinguish the two layers easily.

Server side will adjust the relative location of the two layers to generate a new image. The change vector V1 will be recorded.

The new image along with an instruction will be offered to the user. e.g. Please adjust the relative location to correct the image

User will drag one of the layer to adjust the relative location. After he releases the finger, the relative location change vector V2 will be sent back to the server.

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The server side will determine whether the test is passed. If V1 + V2 = , the...