A Privacy-Preserving Attribute-Based Encryption System for Data Sharing in Smart Cities

Table 1

Comparison of existing schemes.

Methods	Basic algorithm	Unequal attribute comparison	Policy hidden	Outsourcing	Main contribution
[28]	CP-ABE and KP-ABE	No	No	No	The first sketch of ABE for range attributes
[18]	CP-ABE and KP-ABE	Yes	No	No	ABE for Boolean formula over range attributes
[16]	CP-ABE	Yes	Yes	No	Range attribute comparison for AND gates
[29]	CP-ABE	No	Partial policy hidden	Yes	Offline/online attribute-based encryption algorithms
[8]	CP-ABE and KP-ABE	Yes	No	No	Comparable attribute-based encryption using encoding
Proposed	CP-ABE	Yes	Yes	Yes	Attribute comparison and policy hiding