Predicate Fully Homomorphic Encryption: Achieving Fine-Grained Access Control over Manipulable Ciphertext

摘要

With the popularity of cloud computing, there is an increasing demand for enforcing access control over outsourced files and performing versatile operations on encrypted data. To meet this demand, a novel primitive called predicate fully homomorphic encryption (PFHE) is introduced and modeled in this work, which can provide the security guarantee that neither cloud computing server nor invalid cloud users can acquire any extra information about the processed data, while the server can still process the data correctly. We give a generic construction for PFHE, from any predicate key encapsulation mechanism (PKEM) and any LWE-based multi-key fully homomorphic encryption (MFHE). Compared with previously proposed generic construction for attribute-based fully homomorphic encryption (ABFHE), which can naturally be extended to one for PFHE, our construction has advantages in both time for encryption and space for encrypted data storage. In addition, our construction can achieve CCAl-secure. Thus it directly implies approaches for CCAl-secure FHE, CCAl-secure PFHE and CCAl-secure MFHE. The latter two have not been touched in previous work. In addition, we give a conversion which results a CCAl-secure PFHE scheme from a CPA-secure one, drawing on the techniques for CCA2-secure PE schemes.