Reverse Turing Test using Touchscreens and CAPTCHA

Smartphones play an important role in the information-communication society and accesses from smartphones to the Internet services increase more and more with the advent of cloud computing. Smartphones have comparatively small displays and it is possible for users to input data through touchscreens. The techniques such as a CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) that prevent computer programs from automatically accessing to the Internet services require a traditional console. A challenge image is shown in a display and type a response in a keyboard when facing the existing CAPTCHAs, but this may cause a trouble for smartphone users. Thus, it may stunt the growth or development of smartphones. We propose a reverse Turing test using touchscreens and apply to construct a CAPTCHA suitable for smartphones making use of touchscreens to check whether or not embodied knowledge exists in the response data. We experiment and examine its validity, security and usefulness.