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Creating a CAPTCHA with PHP
By: Andrew Walsh
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    2006-06-06

    Table of Contents:
  • Creating a CAPTCHA with PHP
  • How does a CAPTCHA work?
  • Creating the random text
  • Writing the text to the image
  • Check if the user entered the code correctly
  • Improvements and Conclusion

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    Creating a CAPTCHA with PHP - Improvements and Conclusion


    (Page 6 of 6 )

    Well that is all there is to CAPTCHA images just a simple writing of text to an image and storing of the text (key). However the captcha I just described how to build is not the best in the world by a long shot. If you're feeling adventurous you could try the following things:

  • Use a TTF font
  • Move the lines randomly
  • Randomly position the text on the image
  • Rotate the text randomly
  • Use words instead of that string (ie: have a randomly picked word out of say a file of about 1000)About the Author

    Andrew Walsh lives in the UK where he is starting a course of computing and related computer studies at a local college. A programming hobbyist but plans to pursue a career in programming. Currently studying/working with php, mysql, (x)html, css and some limited c++. Sometimes writes code snippets and articles on his personal "development" website at http://walshdev.com/.


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