The future lies in the cloud. Cloud computing is the long dreamed vision of computing as a utility, where users can remotely store their data into the cloud so as to enjoy the on-demand high quality applications and services from a shared pool of configurable computing resources. By data outsourcing, users can be relieved from the burden of local data storage and maintenance. Hence data storage and security is of critical importance to the users so that they can resort to an external audit party to check the integrity of outsourced data when needed.
To accomplish this task we introduce an effective third party auditor (TPA), it should be able to efficiently audit the cloud data storage without demanding the local copy of data, and also prevent any additional on-line burden to the cloud user. The TPA has a great implementation in terms of outsourcing of functionalities and also in providing a higher level of security to organizations as it makes the tracing of the user more complicated. It also acts as a source for storing the data as a result of which the user need not carry the required accessories (s/w, programs etc) in an external flash drive. The best known example of it is the website www.gmail.com where there is memory for a user to store data. User can store data up to a particular size and the same data can be retrieved from any computing resource where there is access to the web.
The same phenomenon is also exhibited in the project but at a lower level of conception. We make use of three entities having their own distinct functionalities and capabilities - sender, third party auditor and receiver. The sender has the obligation of conveyance of data to the third party which plays the role of the auditor, provides storage facility to the data and not adding any burden on the cloud user and provisions for the reclamation of data to the authenticated receiver on demand. The receiver on the other side is the one who gets the audited data securely without the encumbrance of any intruder as the location of Third Party is very secure and special care is taken to keep it safe.
The modified version of RSA is used here so as to provide a higher level of security in the cloud system. The algorithm is called as Structured Multisignature Algorithm as it provisions for the encryption of the message based upon the number of users signing it. So, larger the number of users, greater the level of encryption resulting to a higher level of security. Also the scheme of decryption has to be followed in the exact reverse order of encryption. Failure to do so may result in the message of the sender getting corrupt and unreadable. So even if the intruder manages to get the encrypted message he must also make arrangements to get the exact order of encryption which has a negligible probability of happening.
The main idea of the project can be summarized to the concept of group validation where a number of users furnish their details to generate digital signatures providing a new idea of security. The third party auditor not maintaining a copy of data also adds on to the security capabilities as the data cannot be obtained from third party also. Special care is also taken to observe that data once sent to the receiver is not available to the receiver also on request at the second time as it is deleted from the Third Party Auditor. The remote location of the Third Party makes it even harder to trace the point from where the data is being sent.
