ABnews: A Fast Private Social Messaging System Using Untrusted Storage and Attribute-Based Encryption

Centralized social networking services (SNSs) or online social networks (OSNs) inherently have privacy concerns. Ciphertext-policy attribute-based encryption (CP-ABE) is an effective and promising tool for protecting privacy in centralized and distributed systems. However, a large effort is required to develop new practical social applications using CP-ABE. Furthermore, such applications often have performance problems because of the substantial computation time needed for ABE. This paper describes the design and implementation of the ABnews system, a Usenet-like social messaging system using ABE and untrusted storage. ABnews is fast because it eliminates the heavy computation of ABE from the interactive access to messages. ABnews inherits application programs from Usenet, and allows Usenet's rich newsreaders to be utilized without any modification. Furthermore, ABnews provides overlay social applications, including a private blogging service, a presence service, and one-to-one direct messaging, on top of bulletin board systems. The ABnews system has been implemented using the cpabe toolkit and Google Drive, which holds encrypted messages. Experimental results show that the overhead of CP-ABE is negligible when implementing such a messaging system on a current cloud storage service.