LAUSR

The way services offered by cloud computing gets its unprecedented and undisputed popularity, so its security concerns. Among them the storage as service model (SaaS) is of the forefront of these concerns. SaaS liberates individuals and enterprises from management of IT infrastructure and data centers to concentrate on their core business. Because of untrusted and out-of-premise architecture users are reluctant to outsource their personal and important data. Encryption before outsourcing addresses some of these issues but at the same time strips the data of its useful operation such as sharing and searching. Now to address this issue, the combination of keyword based searchable encryption (KSE) and attribute-based encryption (ABE) leads to an attribute-based keyword searching (ABKS). The resultant combined concept is capable of fine-grained search operation in the multi-owner/multi-user (M/M) setting. However, the underlying costly pairing operation and complex secret sharing mechanism of ABE makes it unsuitable in practical application for resource-limited devices. On top of it, in most of the existing ABKS schemes the size of the secret key and its associated pairing operation linearly expands to the number of attributes. This paper aims at presenting a novel ABKS scheme with pairing-free access verification and constant size secret key based on AND gate access structure and ciphertext-policy (CP) framework. The security of the proposed work is reduced to the standard Decisional Diffie-Hellmen (DDH) assumption, and also collision free and error tolerant. Finally, the performance evaluation and experimental results shows that the proposed scheme improved the overall efficiency and communication overhead.