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Human or Intelligent Machine?

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Concept of ANN and Proposal of new CAPTCHA

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Human or Intelligent Machine?

  1. 1. <ul><li>Concept of Neural Networks </li></ul><ul><li>Towards </li></ul><ul><li>Breaking CAPTCHA </li></ul><ul><li>And the introduction of 3D CAPTCHA </li></ul><ul><li>Ameya Kulkarni </li></ul><ul><li>Ruhi Kulkarni </li></ul><ul><li>Ankit Navlakha </li></ul>
  2. 2. How The Brain Learns ? <ul><li>Structure of brain </li></ul><ul><li>Establishment of Neural Pathways </li></ul><ul><li>Readjustment of parameters to incorporate discrepancies in data. </li></ul>
  3. 3. Biological Neuron <ul><li>Collects signals through dendrites. </li></ul><ul><li>Soma processes these signals and sends out a spike to the axon depending upon a threshold. </li></ul><ul><li>The axon is connected to inputs of other neurons through Synapses. </li></ul><ul><li>Learning occurs by adjusting the synaptic weights. </li></ul>
  4. 4. What is a Neural Network? <ul><li>Definition: An Artificial Neural Network (ANN) is a computing paradigm that can recognize patterns in a given collection of data and produce a model for that data. It resembles the brain in two respects: </li></ul><ul><ul><li>Knowledge is acquired by the network through a learning process (trial and error). </li></ul></ul><ul><ul><li>Interneuron connection strengths known as synaptic weights are used to store the knowledge. </li></ul></ul>
  5. 5. Neural Network Structure <ul><li>Artificial neuron </li></ul>input output <ul><li>An ANN is a set of processing elements (PEs) and connections with adjustable strengths (weights) </li></ul>
  6. 6. How Do Neural Networks Work? <ul><li>Train the Network: </li></ul><ul><li>1. Present data to the network </li></ul><ul><li>2. Network computes an output </li></ul><ul><li>3. Network output compared to desired output </li></ul><ul><li>4. Network weights are modified to reduce error </li></ul><ul><li>Use the Network: </li></ul><ul><li>1. Present new data to the network </li></ul><ul><li>2. Network computes an output based on its training </li></ul>input output
  7. 7. Undistorted image (Training mode) :
  8. 8. Distorted image (Working mode) :
  9. 9. CAPTCHA <ul><li>Completely Automated Public Turing Test to tell Computers and Humans Apart. </li></ul><ul><li>Turing test </li></ul><ul><li>Distorted text that appears when any new account has to be created. </li></ul>FCZH solution
  10. 10. Application After every poll voter has to pass the CAPTCHA test. Online Polls The idea is to require users to solve a CAPTCHA before showing your email address. Protecting Email Addresses From Scrapers To use CAPTCHAs to ensure that only humans obtain free accounts . Protecting Website Registration Proposed Solution Application Area
  11. 11. Breaking Captcha <ul><li>Other techniques like the OCR, Standard dictionary attack, segmentation have shown upto 35% accuracy. </li></ul><ul><li>Using the Neural Network pattern recognition technique an attempt can be made to break the Captcha. </li></ul><ul><li>Greater accuracy will be achieved using this method. </li></ul><ul><li>This would make all the sites today which use this textual CAPTCHA vulnerable to attack. </li></ul>
  12. 12. Proposing a 3D Captcha <ul><li>Manually generate a library of 3D objects </li></ul>
  13. 13. <ul><li>The computer is given a description of each attribute of each object. </li></ul>
  14. 14. <ul><li>Now the remaining process is fully automated. </li></ul><ul><li>The computer randomly picks any objects from the library and they are placed together in a scene. </li></ul>
  15. 15. <ul><li>The individual attributes are labeled with characters. </li></ul><ul><li>The computer is given a set of characters to encode. </li></ul><ul><li>The computer will then list the attributes that correspond to the characters of the sub-address that is being encoded. </li></ul>
  16. 16. An Example <ul><li>Please click on or enter each letter corresponding to the following list in the field below. You must enter them in the exact sequence listed. • The Head of the Walking Man • The Vase • The Back of the Chair </li></ul>
  17. 17. Conclusion <ul><li>Thus, Neural network pattern recognition technique concept can be used in breaking the CAPTCHA. </li></ul><ul><li>The new from of 3D Captcha would be invulnerable to such technique. </li></ul>
  18. 18. Thought for the Future…. <ul><li>Thus, as the machine intelligence increases with biologically inspired computing methods, the need for tougher and tougher CAPTCHA’s arises. </li></ul><ul><li>So , don’t be surprised if one day you cannot create your email account, because you are no more intelligent enough. </li></ul>
  19. 19. References <ul><li>Artificial Intelligence by Elaine Rich and Kevin Knight. </li></ul><ul><li>Artificial Neural Networks in Real-life Applications -by Juan Ramon Rabunal, Julian Dorrado. </li></ul><ul><li>spamfizzle.com/CAPTCHA.aspx </li></ul><ul><li>www.captcha.net/ </li></ul>
  20. 20. THANK-YOU.

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