International Journals of Advanced Information Science and Technology (IJAIST)
A cloud storage system consists of a collection of storage servers over the internet. The main aim is to provide secure storage services in a cloud storage system. Encryption schemes are used to provide data confidentiality, data robustness and functionality. Data confidentiality can be achieved through encryption but it limits the functionality of the storage system because a few operations are not supported over encrypted data. The storing cryptographic key in a single device is risky. It address the problem of forwarding data to another user by storage servers directly under the command of the data owner.