Efficient keyword search over encrypted data in multi-cloud setting

With the emergence of cloud storage, enabling cloud clients to securely store and efficiently retrieve ciphertext is a fundamental issue in cloud computing as data outsourcing can greatly ease heavy computation and management burden locally. Unfortunately, two challenging issues (i.e., data security and privacy) dramatically impede the adaption and practicability of cloud storage due to honest-but-curious cloud service provider (CSP). Furthermore, data encryption mechanism seriously makes the information retrieval over ciphertext extremely difficult. Besides, dealing with single CSP is predicted to become less popular with cloud customers for fear of risks of single-point failure threats and potential malicious insiders. To this end, we propose two efficient keyword search over encrypted data in multi-cloud setting schemes which exploit Identity-Based Encryption (IBE) and Key-Policy Attribute-Based Encryption (KP-ABE), respectively. Formal security analysis proves that our schemes can guarantee data privacy and reliability. As a further contribution, experimental results over real-world dataset show that our proposed schemes are feasible and efficient in practical applications.