R. Kalaichelvi et al./ Elixir Comp. Sci. & Engg. 56 (2013) 13481-13484 13481 1. Introduction A. Cloud Computing Cloud computing is a promising, evolving Internet computing of this era. It presents the users with a secure storage for storing the documents online wherein the users can take the benefit of privilege to access it remotely avoiding the usage of the data storage services. The companies which use the newly developed cloud computing model purchase the computing resources with the capabilities of scalability of expanding the resources, providing on-demand privilege with a little or no up- front IT infrastructure investment costs. A new profitable way of delivering computing resources are done through cloud. It is a mixture of various computing entities, globally separated, but electronically connected. It is an Internet - based service delivery model. It offers services to markets like hospitals and business regimes. Cloud computing has taken IT to an upper level by giving people of the digital world to store information with bendable and measurable processing capability to cope up with the expanding need of demand and supply, whilst reducing capital expenditure. Cloud computing uses imaginary substructure and constructs a network, which can be used as the services in distributed computing, software services, internetworking, and internet services. It has exhibited enormous effort to empower fast, secure, trustable, integral, with a high performance, quantifiable, available data maintenance and security. B. Service Models: The deployment of the cloud computing services will vary based on the necessity of any business model once the cloud is formed. The basic service models [1] which can be deployed are as listed below: Infrastructure as a Service (IaaS): IaaS provides the customers the virtual devices that persuade the necessities on the needs of the customer services and the applications such as memory, CPU, OS and data space, reducing the expenses and the use of devoted systems. IaaS presents an intermediary policy to run subjective OS and software in case of scrupulous service constraints. Platform as a Service (PaaS): PaaS is an application platform wherein users can purchase access to the platform so that they can deploy their own softwares and the conventional applications with their services on the cloud. It is more economical, even though services need to be supported and managed. PaaS distributes application development tools. Testing, collaborating, hosting, and managing applications are the services can be done by PaaS. It conceals the details of handling hardware. All support for the construction and distribution of web based applications are offered by PaaS online. Software as a Service (SaaS): For software operation in cloud system, SaaS is a prototype. The providers offer software to the clients through SaaS on demand. Users can buy the right to use and make use of an application or service that is hosted in the cloud. A standard example of this is Salesforce.com [12] in which the necessary knowledge for the interaction between the consumer and the service is organized as an element of the facility in the cloud. C. Deployment Models The cloud models [2] based on where they are deployed is divided into four types which can be explained as below: Public Cloud: This model is offered through the web applications or the website services online wherein sharing the hosting of information or the application is possible. A third party buys this kind of cloud model and the user can just use the services paying out a certain amount based on the efficacy. Private Cloud: Private cloud is mainly used for the internal utilization of any organization within its firewall, which is owned and managed by the company itself. The user working for that company only can make use of the resources available on the cloud which is bought by the owner. The user can make use of Tele: E-mail addresses: kalai_hasan@yahoo.com © 2013 Elixir All rights reserved Secure and Robust Cloud Storage with Cryptography and Access Control R. Kalaichelvi 1 and L. Arockiam 2 1 Department of Computer Science, Karpagam University, Coimbatore, India. 2 St. Joseph's College, Tiruchirappalli, India. ABSTRACT Cloud computing is a new evolving paradigm to a wide range of users like individuals, businesses and governments to provide resources in an on-demand environment. Enterprises store their incredible abundance of data on cloud to reduce data management cost. In addition, an emerging class of entrepreneurs is taking advantage of clouds as they might not have enough finance to purchase resources or ensure the necessary security. As the data is stored on cloud service providers' servers, confidentiality, authentication and access control are the most challenging factors in data security. Cloud providers should provide adequate security measures on their data and applications. Cryptography access control architecture overcomes the issue of data security in cloud environment. In this paper, we illustrate a secure and robust cloud storage architecture by combining cryptography and access control with two layered encryption. © 2013 Elixir All rights reserved. ARTICLE INFO Article history: Received: 17 February 2013; Received in revised form: 11 March 2013; Accepted: 12 March 2013; Keywords Authentication, Cryptography, Data security, Encryption. Elixir Comp. Sci. & Engg. 56 (2013) 13481-13484 Computer Science and Engineeering Available online at www.elixirpublishers.com (Elixir International Journal)