Abstract Progressive Visual Cryptography (PVC) is quite suitable for sharing sensitive digital data where, as the number of stacked share increases, more black regions will be decrypted. Over the past few years, designing of progressive visual recovery technique has been studied by many researchers. Previous research on PVC, such as Fang et al. (2006) and W.P.Fang et al. (2008) were all carrying pixel-expansion problem... Progressive Visual Cryptography (PVC) is quite suitable for sharing sensitive digital data where, as the number of stacked share increases, more black regions will be decrypted. Over the past few years, designing of progressive visual recovery technique has been studied by many researchers. Previous research on PVC, such as Fang et al. (2006) and W.P.Fang et al. (2008) were all carrying pixel-expansion problem and also gives a poor visual quality on the recovered stacked image. Recently, Hou et al. have developed a progressive scheme for secret sharing. In Hou et al. scheme, secret object bits are encrypted sequentially by using randomly chosen number from encoding matrices. It is observed that shares generated by the Hou scheme are free from pixel expansion problem, but shares are not fully secure and even discloses secret itself in construction phase of encoding. In this paper, we propose a new robust progressive algorithm based on logistic chaotic map to overcome the said limitation of Hou scheme. The irregular outputs of the logistic map are used to encode a secret digital information carrying image. To provide robustness during the encoding process of the share, noise has been introduced along with chaotic sequences. The performance of the algorithm in the scheme of Hou is critically analyzed and compared with new suggested scheme. Empirical results are presented to showcase the performance of our proposed scheme in terms of its effectiveness (imperceptibility and security) and feasibility. Read More Read Less

Abstract Virtual environments are increasingly being used as a medium for conducting business activities. Compared with the physical environments, they offer a faster medium for carrying out activities, especially so when geographical distances are great. The key factor impeding the adoption of e-business is trust. This is because trusting agent and trusted agent might never meet each other in face-to-face or at best this... Virtual environments are increasingly being used as a medium for conducting business activities. Compared with the physical environments, they offer a faster medium for carrying out activities, especially so when geographical distances are great. The key factor impeding the adoption of e-business is trust. This is because trusting agent and trusted agent might never meet each other in face-to-face or at best this is limited. However, building trust is difficult and requires significant effort. Once trust has been well established, it needs to be maintained. In order to maintain trust, the trusting agent and trusted agent need a Service Level Agreement (SLA) as a guideline to carry out the interaction and to monitor performance progress during trust maintenance. In this paper, we propose a framework by which both parties can reach an SLA based on their requirements. The framework includes service formalization and service negotiation. Service formalization is a way to gather information about the other party’s requirements. Service negotiation is a process by which an agreement can be reached if there are any conflicting requirements. A case study is presented to illustrate the operability of the framework. Read More Read Less

Abstract There are many cryptographic systems that use complex operations involving substitutions and permutations to produce resistant ciphertext, even if the level of the security of these cryptosystems are good, there should be tradeoff between security level and operational cost and the ever increasing virtual infrastructure and mobile, cloud computing technologies creating much more complexities and demanding cost effective and secure cryptographic algorithms. In order... There are many cryptographic systems that use complex operations involving substitutions and permutations to produce resistant ciphertext, even if the level of the security of these cryptosystems are good, there should be tradeoff between security level and operational cost and the ever increasing virtual infrastructure and mobile, cloud computing technologies creating much more complexities and demanding cost effective and secure cryptographic algorithms. In order to make a cipher more difficult to break, one could use various keys in cryptosystem. This would help to cover any perceptible patterns in the ciphertext. In fact, one can produce unbreakable ciphertext by supplying randomly generated key on each bit of data that is mathematically infeasible to break. Since different random bits or keys would not lead to any repeating patterns. For the first time, in this paper, we present a construction method to generate multiple random keys from a core-key with highest possible immunity to crack. We are with a particular emphasis on novel technique to secure user data, we have designed a secure and cost effective new cryptosystem called Rbits (Random bits) cipher. In different directions we identify that Rbits having highest immunity to crack and presenting various analysis tests in support from this viewpoint. Read More Read Less