Honggang Liu

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Most commonly used CAPTCHAs are text-based CAPTCHAs which relay on the distortion of texts in the background image. With the development of automated computer vision techniques, which have been designed to remove noise and segment the distorted strings to make characters readable for OCR, traditional text-based CAPTHCAs are not considered safe anymore for(More)
CAPTCHAs are employed as a security measure to differentiate human users from bots. A new sound-based CAPTCHA is proposed in this paper, which exploits the gaps between human voice and synthetic voice rather than relays on the auditory perception of human. The user is required to read out a given sentence, which is selected randomly from a specified book.(More)
Graphical passwords are believed to be more secure than traditional textual passwords, but the authentications are usually complex and boring for users. Furthermore, most of the existing graphical password schemes are vulnerable to spyware and shoulder surfing. A novel graphical password scheme ColorLogin is proposed in this paper. ColorLogin is implemented(More)
A novel self-adaptive image denoising model based on scale correlation and Stein’s unbiased risk estimate-linear expansion of thresholds (SURE-LET) in the nonsubsampled contourlet transform domain is proposed in this paper. First we implement the multidimensional and translation invariant decomposition for spatial images by the nonsubsampled contourlet(More)
Authentication is a process that ensures a user's identity. User's identity can be verified by user name and password. The textual passwords are the most widely used passwords for authentication. There is a common trend among users to choose short length passwords which are easy to memorize. However, textual passwords are vulnerable to various(More)
Growth of Internet and its usage has made web services prone to malicious threats by automated scripts or bots. "Completely Automated Public Turing Test to tell Computers and Humans Apart", commonly abbreviated as CAPTCHA, is a technique used by web services to differentiate between humans and bots. [1] Most of these techniques are based on recognizing the(More)
IBM first proposed the conception of autonomic computing (AC) which provides a new way for computer technology. At present there are many researches on AC system, but less research on AC theory and evaluation. However it is the most import for the development of AC domain. In this paper, we mainly summarize present evaluation criteria, evaluation tools and(More)
Authentication is the process of identifying an individual, usually based on username and password. Authentication merely ensures that the individual is who he or she claims to be. This forestalls the activities against confidentiality and integrity. Shoulder surfing is the main problem of graphical passwords. To overcome the problem of shoulder surfing we(More)
Cloud computing as a new technology in the IT industry has undergone a major change, and the smart grid informatization construction cannot be done without a cloud computing platform. This gives the power of cloud computing platform architecture. Electric cloud application environment of wide distribution, large amount of data, heterogeneous, real-time(More)
Autonomic computing (AC) is a new domain, based on AC theory to design autonomic system is not perfect and implement process is more difficult. Especially, there lack tools and models to test the autonomic system. According to above-mentioned reason, this paper mainly discusses dependability of autonomic software. We proposed a model to analyze autonomic(More)