Branching Messaging for Anonymous Communication


We consider anonymous communication between pairs of nodes in the presence of an adversary who can observe all network traffic. Existing schemes involve partially trusted central servers, a large amount of cover traffic, or high latency. We propose a scheme which improves upon the trade-off, in which messages require only logarithmic time to deliver, as well as computational time to send. In this scheme, any node receiving a message applies a private decryption key to discover content,or instructions to forward the message to zero or more other nodes. Furthermore, when a node applies its decryption key to a message not encrypted with that node’s encryption key, the result is indistinguishable from a message with forwarding instructions. A sender wraps a message in an onion route of logarithmic length, branching (forwarding to multiple nodes) at random points, resulting in a tree of forwarded messages. Nodes wait to initiate messages of their own until they have received a message, so it is indistinguishable whether they are sending or forwarding. Through analysis and simulation, we show this system preserves a high degree of sender and receiver anonymity,as well as unlinkability between communicating pairs

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