Net) is a bad idea, as there are many failure modes.
We recommend that you use a well-tested implementation such as re CAPTCHA.
re CAPTCHA also comes with an audio test to ensure that blind users can freely navigate your site. Instead of typing letters, you authenticate yourself as a human by recognizing what object is common in a set of images. Up until a few years ago, most of these services suffered from a specific type of attack: "bots" that would sign up for thousands of email accounts every minute.
re CAPTCHA is our officially recommended CAPTCHA implementation. This was the first example of a CAPTCHA based on image recognition. Most bloggers are familiar with programs that submit bogus comments, usually for the purpose of raising search engine ranks of some website (e.g., "buy penny stocks here"). By using a CAPTCHA, only humans can enter comments on a blog. The solution to this problem was to use CAPTCHAs to ensure that only humans obtain free accounts.
Since a parser could easily be written that would allow bots to bypass this test, such "CAPTCHAs" rely on the fact that few sites use them, and thus that a bot author has no incentive to program their bot to solve that challenge.
True CAPTCHAs should be secure even after a significant number of websites adopt them. In general, making your own CAPTCHA script (e.g., using PHP, Perl or .
There is no need to make users sign up before they enter a comment, and no legitimate comments are ever lost! In general, free services should be protected with a CAPTCHA in order to prevent abuse by automated scripts. Spammers crawl the Web in search of email addresses posted in clear text.
Many implementations of CAPTCHAs use undistorted text, or text with only minor distortions. In addition to making the images unreadable by computers, the system should ensure that there are no easy ways around it at the script level.The following guidelines are strongly recommended for any CAPTCHA code: Accessibility. CAPTCHAs based solely on reading text — or other visual-perception tasks — prevent visually impaired users from accessing the protected resource.Such CAPTCHAs may make a site incompatible with Section 508 in the United States.The club's landing page - find all relevant information like the actual squad, relevant news, recent rumours and the most important information on the club's performance. A CAPTCHA is a program that protects websites against bots by generating and grading tests that humans can pass but current computer programs cannot.