Additional code in a Web page
number of friends for additional code really does not understand. So what is the additional code, why do you want to use additional code it? Simply a verification code is a bunch of random numbers or symbols, and generates an image, pixel plus some interference in the picture, Visual recognition by the user with the CAPTCHA information, entry form submission site verification, validation is successful before using these features. Verification code is to prevent the use of robot automatic bulk registration, for specific registered users from using specific programs brute force constant land and irrigation.
network security increasingly serious
now the Internet faster and faster, Internet access has become more smooth at the same time, network security issues are more serious. Speed assurance, like a brute force password cracking and dictionary password cracking attack methods such as chances of success more and more. Hackers can take advantage of online crack tool to break a number of card number and password, once you have a password login system is ready for operation. In the case of can't stop password account has been cracked, how to guard against such security problems? Additional code came into being. Role of the additional code
so to speak, additional code can effectively prevent exhaustive method of the HTML page. Enumeration method is to use some letter combinations to keep trying until you find the correct password, in the process of trying, real password or, if the real password change will greatly increase the difficulty of cracking, success almost impossible to crack. Additional code is using the brute force method, a weakness during validation add the dynamic validation of content, would effectively prevent exhaustive method of attack.
append the code randomly generated on the WEB server and your record, then generate the text to the user, user manual input is submitted, additional code submitted to the server with a note of additional code compare, if you are correct and the user name is correctly validated.
additional code is also defective
If you attach code to text is returned to the browser in the form of words, some software can also automatically fill in the attached code and try again. So how to solve this problem?
returned with pictures attached code can effectively solve the problem. Pictures are presented to the user in a manner to some software does not recognize the format of the picture. If you need additional security, you can also add interference picture pyramid, plus interference can effectively increase the picture identification more difficult. For example, some additional code is added to site interference, some color words and so on.