Deep-CAPTCHA: a deep learning based CAPTCHA solver for vulnerability assessment
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CAPTCHA is a human-centred test to distinguish a human operator from bots, attacking programs, or any other computerised agent that tries to imitate human intelligence. In this research, we investigate a way to crack visual CAPTCHA tests by an automated deep learning based solution. The goal of the cracking is to investigate the weaknesses and vulnerabilities of the CAPTCHA generators and to develop more robust CAPTCHAs, without taking the risks of manual try and error efforts. We have developed a Convolutional Neural Network called -CAPTCHA to achieve this goal. We propose a platform to investigate both numerical and alphanumerical image CAPTCHAs. To train and develop an efficient model, we have generated 500,000 CAPTCHAs using Python Image-Captcha Library. In this paper, we present our customised deep neural network model, the research gaps and the existing challenges, and the solutions to overcome the issues. Our network's cracking accuracy results leads to 98.94% and 98.31% for the numerical and the alpha-numerical Test datasets, respectively. That means more works need to be done to develop robust CAPTCHAs, to be non-crackable against bot attaches and artificial agents. As the outcome of this research, we identify some efficient techniques to improve the CAPTCHA generators, based on the performance analysis conducted on the Deep-CAPTCHA model.
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