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A CAPTCHA, elaborated as a Completely Automated Public Turing Test to Tell Computers & Humans Apart is a popular software used to prevent automated bots from engaging the web applications and hogging resources. All the available CAPTCHA formats remain insufficiently resistant to bots, especially when combined with a relay attack. We propose a new type of dynamic CAPTCHA that is resistant to automated as well as relay attacks due to its dynamic nature. In our CAPTCHA, the user needs to identify a moving object as the target, from among a number of randomly moving decoy objects and trace that target with the mouse cursor. The user passes the test when they are able to trace the target for a certain amount of time. The latency introduced to the remote solver makes it difficult to break the CAPTCHA since the target object moves dynamically. It is also difficult for a bot to track the target using image processing because there are a number of similar looking objects. With the CAPTHCA‟s parameters set to suitable value, a relay attack cannot be established economically and false acceptance rate with bots are minimized without affecting human success rate. 


CAPTCHA, Relay attack, Automated bot.

Article Details

How to Cite
Abhishek Chaudhary, Prathamesh Deogharkar, Sapna Dhanraj, and A. R. Sonule, “DYNAMIC CAPTCHA”, IEJRD - International Multidisciplinary Journal, vol. 5, no. 5, p. 6, Jun. 2020.


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