Image Captcha: Website terms of randomly generates
an image that says numbers, letters or a combination of Chinese characters, and
then asks the user to enter the contents of the image, and submits along with
the form. The main means to break the image captcha is OCR. 20 years ago, OCR
technology is still a big problem, but now has a mature solution, and OCR
technology is mainly based on the results of relevant research in artificial
intelligence neural network implementation. To deal with OCR technology, image
captcha has been upgrated, with noise background and distorted text to
interference 代答. Against the noise background is
the main method of color filter noise, and there is the shrinkage of OCR target
range, such as restrictions in the 26 letters of the alphabet to be recognized
without special symbols, etc.; to deal with distorted text interference method
is mainly based on the text texture vector and then calculate their baseline
distortion and restore the text.
Voice Captcha: It is often used as image captcha
supplement, making ??available to people with visual impairments. The method of
attack is similar as image captcha, and voice captcha is the magic weapon
against it. Of course, a lot of voice captcha also uses the background noise and
other interference, but how to deal with this kind of interference is another
issue.
Intelligence test answer captcha: Another design
ideas for 人工代答 is more interesting, but also
more difficult to attack. Its working principle is determined by the server of a
random simple common sense mental problems to end users, and allow end users to
answer. For example, there are three pieces of scenery in the four pictures, a
building, and then let the user select building; another example requires the
user to compute 5+25 is equal to the number, fill in the answer; and let the
user answer between TV, refrigerator, hair dryer and movie ticket, which is not
a household appliance. Intelligence test answer captcha has many ways, varied,
and the text can also be the theme of the picture. Want to break this captcha
with considerable difficulty, but also need the wisdom combined with advanced
computer image captcha bypass technology. But at least for the test subject can
help text natural language analysis techniques and search engines to attack. The
captcha questions in natural language word to identify SVO shape up and
construct a keyword search using Google, and then calculate the weights voting
results, you can get a "most likely the correct answer."
With the popularization of the Internet, Internet
users continues to increase, captcha bypass service requirements are
highlighted. In the face of increasingly complex captcha, 人工答题 has appeared in large numbers, which can be said to solve
all the captcha bypass problem!