In today's community and social communication, we cannot deny that social network and media play the biggest part in our typical daily life. We can see that more information is displayed on the social media sites. New social media sites have also increased each day. However, when most of the people use a social network, they tend to put in all of their information into the social network profile without knowing any threats that may come to them from the complete stranger who can look at their profile. This is especially the case for children under thirteen who are prone to information stealing and phishing. This research, therefore, designs and implements a new mobile application that will help parents monitor their children's activities on social network so that any foreseeing threats can be detected before harming their children

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<p>The objective of using threshold cryptography on cloud environment is to protect the keys, which are the most important elements in cryptographic systems. Threshold cryptography works by dividing the private key to a number of shares, according to the number of virtual machines, then distributing them each share to each virtual machine. In order to generate the key back, not all the shares are needed. Howerver, the problem is that there has been no research attemping to find a suitable threshold value for key reconstruction. Therefore, this paper presented a guildline designed and implemented that can assist to choose such value. The experiment was setup using CloudSim to simulate cloud environment and collecting time taken in key distribution and key reconstruction process to achieve the optimal threshold value.</p>

Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark.I am grateful for a lot of support from many people. Authentication and Access Control: Practical Cryptography Methods and Tools was originally just an idea and a dream. Without the wonderful support from the Apress team, this book would never become a reality. I am especially indebted to Susan McDermott, Rita Fernando, and Laura Berendson for their hard work and encouragement. I am also thankful for the helpful comments from Kazumasa Oida, the technical reviewer of the book. His comments have definitely made the book better. This book includes a lot of research done by myself and my students. Therefore, it is a good place to thank them here.Finally, I would like to acknowledge the support from my family. I am the luckiest person in the world to be surrounded by so many loving and supportive people.

Most of today's authentication mechanisms only involve the use of username and password. This is known as one-factor authentication. Even though the method is the most commonly used, there have been problems with its security. This research, therefore, aims to design and develop a two-factor authentication that can improve the security of authentication mechanism. The proposed method contains an extra factor of authentication in image. Combining with the use of username and password, users are allowed to draw anything they want to make up another factor. This makes it different from other existing image authentication mechanisms which force users to choose pre-defined images. The proposed method was tested with thirty users to determine the most appriate security threshold. The performance of the system was evaluated, and the satisfactory survey was also taken.