The role of those systems using and providing cloud computing are more and more important among today's information systems. By using cloud infrastructure model we can acquire general and shared access to shared computer resource sets in a fast and easy way and with marginal interactions of the service provider .
However, with this new information system model new issues arise. The greatest challenge is how to keep secure data in the cloud. Tresorit provides a solution for this problem. Tresorit’s file sharing service combines privacy consciousness with the benefits of the cloud by its client-side encryption. Because of the growth in mobility the demand is increasing for developing access for the users to their encrypted files via web browsers in addition to the existing desktop and mobile clients. Nevertheless, the operation of the current system is not compatible with the constraints of the web.
In my thesis I examine the architecture of the existing system of Tresorit, in particular the login process of the user. I plan a new service interface which not only fulfills the requirements of the web environment but also offers security on a level similar to the existing clients. I implement this new service interface as a new backend service, so that the login to the Tresorit system as well as the use of its other services will be available to the web client. By multiple-level testing process I assure that the realized service is correct, and for this process I set up a matching testing framework.
 P. Mell és T. Grance, „The NIST Definition of Cloud,” Szeptember 2011.