ABSTRACT
This chapter presents new construction of Ciphertext Policy Attribute-Based Encryption, named Privacy-Preserving Constant Ciphertext Policy Attribute-Based Encryption, in which it can reduce the ciphertext to a constant size with any given number of attributes. Ciphertext Policy Attribute-Based Encryption enforces expressive data access policies, and each policy consists of a number of attributes. Privacy-Preserving Constant Ciphertext Policy Attribute-Based Encryption leverages a hidden policy construction such that the recipients’ privacy is preserved efficiently. In addition, a Privacy-Preserving Attribute-Based Broadcast Encryption (PP-AB-BE) scheme is presented, in which compared to existing BE schemes, PP-AB-BE is more flexible because a broadcasted message can be encrypted by an expressive hidden access policy, either with or without explicitly specifying the receivers.
