A novel verification code technology to make web system more secure

Verification code technology is designed to distinguish humans from computers using distorted letters and/or numbers, to protect websites from machine attacking. The current verification code technology faces a problem: too simple to prevent an attacking machine to recognize automatically, or too complex for a human user. It will be hard for us to decide which to choose? This paper proposes a novel method. The verification code will be meaningful and can be simple, and some random meaningful images are also transferred to the client at the same time, people should not only input the verification code, but also need to choose one image whose content has the same meaning with verification code. For example, the verification code is “cat”, and transferred images will contain an image of cat, user should select the cat image so that he/she may pass the validation. Theoretical analysis and simulation experiments illustrate that this method is effective, safe and with low complexity.