Why isn the captcha code distorted?
As mentioned in the above question, captchas challenges are easily circumvented by automated OCR analysis. A quick look through standard digital image processing texts will show that common distortion techniques such as color blur, text bending, noise degradation, etc do not really make it more difficult for OCR programs to decipher the image code. Highly distorted images and more complicated challenges (i.e. entering three words out of ten that are present in the image) do decrease the success rate of OCR programs. But even if an OCR success rate were reduced by half or more, it would not provide a significant barrier to brute force robots; they would continue to guess. And these type of captchas are still susceptible to the “free-porn-if-you-solve-the-captcha” attack. In addition, the excessively complicated challenges are often problematic because humans also have more difficulty deciphering and solving them. Having said that however, ProxyPass does include configuration options to
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