An Authenticated Keyword Searchable Conditional Proxy Re-encryption Scheme in Cloud Services

The internet and mobile platform together are playing a vital role in making people to keep and manage their data conveniently using cloud services. This made cloud servers to manage larger volume of data where data confidentiality has to be taken into consideration. The major issue is to overcome the tradeoff between satisfactory mobility and security and privacy in cloud environment. A long time the researches in this field focused on encryption and decryption techniques to protect data owners' privacy and data confidentiality. These encryption and decryption techniques made another essential requirement to be focused such as searching on encrypted data. This leads to the evolution of techniques for searching on encrypted data. Further in another direction conditional proxy re-encryption scheme where cipher text satisfying certain keyword vector set determined by the owner can be re-encrypted by a proxy server started getting attention. However, the combination of both searching and hierarchical conditional proxy re-encryption has been attempted recently. In this paper the above scheme is analyzed and proved that the data owner authentication offered by the scheme is fails to satisfy the requirement of authentication property. Additionally an extended version of the scheme is proposed which ensures data owner authentication. The proposed scheme is analyzed and proved based on widely used BAN logic and AVISPA.