JavaScript-A verification code design ideas, have experience in this area please participate in the discussion!!

Draw a picture, better understand. The site in the verification of the need for this is relatively strong (and even the resulting user resentment can be no matter), mainly security considerations.
With reference to TB hardening, the following validation procedures have been designed, so please discuss how to optimize security!
As for the code will be written, it is not necessary.

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Draw a picture, better understand. The site in the verification of the need for this is relatively strong (and even the resulting user resentment can be no matter), mainly security considerations.
With reference to TB hardening, the following validation procedures have been designed, so please discuss how to optimize security!
As for the code will be written, it is not necessary.

1 verification code is mainly to prevent brute force, the server Best plus the number of errors limit
2 In addition to the Ajax front-end Verification verification code is correct, but also on the server authentication
3 "Generate related MD5 according to different click order" from your description, you feel that you are the record of the need to click on the location, for example, 134563 corresponds to the "ancestor said the flower said," Then you pass is 134563 MD5 value This simple MD5 value is very easy to be violent cracked. If you do this, it is recommended that you use complex MD5
4 This is only the "tip of the iceberg" of site security, or not, first filter SQL injection and XSS. These are not important.

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