Although research provides anonymous Internet communication schemes, anonymous Internet services, e.g.~receiver anonymity, received only limited attention. In this paper we present SARA (Anonymous Overlay Routing Providing Sender and Receiver Anonymity), which enables sender, receiver and relationship anonymity using layered encryption and distributed traffic mixes, similar to a Chaumian Mix. Via IP-datagram service and address virtualization it is fully transparent to applications. Organized as structured P2P network, SARA is highly scalable and fault tolerant.
In SARA each communication partner randomly selects a number of nodes from the overlay and concatenate these to an anonymous communication path. The sender selects the head of the path. The receiver builds the tail and publishes this information in the overlay network using an anonymous ID. Via this ID the sender retrieves the tail nodes of the path and concatenates both path section. Layered encryption hides the identities of the sender, receiver and the intermediate nodes.