Integrity verification in multi cloud storage

A Text-editor application which incorporates the Co-operative provable data possession scheme allows the user to upload files, request for a challenge/proof check, view the contents of the file in a secure manner and allows him/her to audit the files which he stored in the cloud. High security is guaranteed because the data of the user passes through two levels of storage. The algorithm focuses on increasing security, without compensating on performance. The attacker may view the contents of the file, which is double encrypted. If the cloud service provider, modifies the content of the cloud, it will be detected during the proof checking phase, which is performed before the user attempts to view the contents of the file. Further, user can edit dynamically with new content, which also gets encrypted and stored in the cloud. User can download the content and later upload it with changes. The communication between third party server and cloud server is trusted, as communication is based on exchange of public - private RSA keys.