HRPACS: A Non-End-to-End Anonymous Communication System Based on Hybrid Routing Policies

With the advent of Internet technology, individuals can easily communicate with each other and access online services from virtually anywhere in the world. While various cryptographic algorithms are used to secure transmitted content online, some critical data, like users’ network addresses, remains vulnerable, thus raising privacy concerns. Anonymous Communication Systems (ACSs), such as The Onion Routing network (Tor), The Invisible Internet Project (I2P), DC-net, and Freenet, were developed to address these issues. However, despite their long-standing use, many new anonymity techniques have not been integrated, and advancements in de-anonymization attacks highlight the need to reassess their effectiveness. Furthermore, network censorship and blocking have restricted access to these ACSs in certain areas. This paper presents a novel ACS called HRPACS, which incorporates several recent anonymity techniques, including blockchain and linkable ring signature technology. HRPACS uses a two-phase routing strategy and proposes an Introducer Mechanism to combat network blocking while using a broadcast strategy to achieve non-end-to-end anonymous communication, and utilizes homomorphic encryption to dynamically generate target communication addresses and employs blockchain technology to establish autonomous connections between nodes without the need for pre-existing trust. Security analyses demonstrate that the proposed anonymous communication scheme meets the anticipated anonymity requirements. Furthermore, simulation experiments indicate that HRPACS performs as intended.