Published Paper Details:

Attribute-based Encryption (ABE) has been widely used in cloud computing where a data provider outsources their encrypted data to a cloud service provider and can share the data with users possessing specific credentials. However, the standard ABE system does not support secure Deduplication, which is crucial for eliminating duplicate copies of identical data in order to save storage space and network bandwidth. Here, we present an attribute-based storage system with secure Deduplication in a hybrid cloud setting, where a private cloud is responsible for duplicate detection and a public cloud manages the storage. Compared with the prior data Deduplication systems, this system has two advantages. Firstly, it can be used to confidentially share data with users by specifying access policies rather than sharing decryption keys. Secondly, it achieves the standard notion of semantic security for data confidentiality while existing systems only achieve it by defining a weaker security notion. In addition, we put forth a methodology to modify a cipher-text over one access policy into cipher-texts of the same plain-text but under other access.