Multi-user protocols with access control for computational privacy in public clouds
This addresses computational privacy for multi-user cloud environments, offering a novel extension to FHE for practical applications.
The paper tackles the problem of scaling fully homomorphic encryption (FHE) to multi-user cloud applications with varying trust levels, presenting a Complementary Key Pairs technique and protocols that enable attribute-based access control while keeping the server oblivious, with analysis of security and no assumptions on the underlying FHE scheme.
Computational privacy is a property of cryptographic system that ensures the privacy of data being processed at an untrusted server. Fully Homomorphic Encryption Schemes (FHE) promise to provide such property. Contemporary FHE schemes are suited for applications that have single user and server. In reality many of the cloud applications involve multiple users with various degrees of trust and the server need not necessarily be aware of it too. We present a Complementary Key Pairs technique and protocols based on that to scale any generic FHE schemes to multi user scenarios. We also use such technique along with FHE to show how attribute based access control can be achieved while server being oblivious of the same. We analyze the protocols and their security. Our protocols don't make any assumptions on how FHE scheme itself works.