Attribute-Based Authenticated Key Exchange

We introduce the concept of attribute-based authenticated key exchange (AB-AKE) within the framework of ciphertext-policy attribute-based systems. A notion of AKE-security for AB-AKE is presented based on the security models for group key exchange protocols and also taking into account the security requirements generally considered in the ciphertext-policy attribute-based setting. We also introduce a new primitive called encapsulation policy attribute-based key encapsulation mechanism (EP-AB-KEM) and then define a notion of chosen ciphertext security for EP-AB-KEMs. A generic one-round AB-AKE protocol that satisfies our AKE-security notion is then presented. The protocol is generically constructed from any EP-AB-KEM that achieves chosen ciphertext security. Finally, we propose an EP-AB-KEM from an existing attribute-based encryption scheme and show that it achieves chosen ciphertext security in the generic group and random oracle models. Instantiating our AB-AKE protocol with this EP-AB-KEM will result in a concrete one-round AB-AKE protocol also secure in the generic group and random oracle models.