Weighted Attribute Based Conditional Proxy Re-Encryption in the Cloud

Conditional proxy re-encryption (CPRE) is an effective cryptographic primitive language that enhances the access control mechanism and makes the delegation of decryption permissions more granular, but most of the attribute-based conditional proxy re-encryption (AB-CPRE) schemes proposed so far do not take into account the importance of user attributes. A weighted attribute-based conditional proxy re-encryption (WAB-CPRE) scheme is thus designed to provide more precise decryption rights delegation. By introducing the concept of weight attributes, the quantity of system attributes managed by the server is reduced greatly. At the same time, a weighted tree structure is constructed to simplify the expression of access structure effectively. With conditional proxy re-encryption, large amounts of data and complex computations are outsourced to cloud servers, so the data owner (DO) can revoke the user's decryption rights directly with minimal costs. The scheme proposed achieves security against chosen plaintext attacks (CPA). Experimental simulation results demonstrated that the decryption time is within 6-9 ms, and it has a significant reduction in communication and computation cost on the user side with better functionality compared to other related schemes, which enables users to access cloud data on devices with limited resources.