Abstract :
To distinguish between users who operate on a network client is a person rather than a machine, each site in the registration, login, posting, query and other stages introduce the technology of CAPTCHA, has achieved obvious results when websites be attacked on. In this paper, the traditional CAPTCHA technology is classified and summarized. Because of the human pattern recognition ability is superior to machines, so finger-guessing game mechanism is introduced in CAPTCHA technique. This kind of technique needs machine to be done the secondary logic judgment, when some image CAPTCHAs have to be identified. It´s hard for machines to pass. Because of the broader population base of fingers play, this kind of mechanism significantly reduced the difficulty of human identification, it is one of the existing image CAPTCHA technology progress.
