  Anonymous communication networks (ACNs) enable Internet browsing in a way
that prevents the accessed content from being traced back to the user. This
allows a high level of privacy, protecting individuals from being tracked by
advertisers or governments, for example. The Tor network, a prominent example
of such a network, uses a layered encryption scheme to encapsulate data
packets, using Tor nodes to obscure the routing process before the packets
enter the public Internet. While Tor is capable of providing substantial
privacy, its encryption relies on schemes, such as RSA and Diffie-Hellman for
distributing symmetric keys, which are vulnerable to quantum computing attacks
and are currently in the process of being phased out.
  To overcome the threat, we propose a quantum-resistant alternative to RSA and
Diffie-Hellman for distributing symmetric keys, namely, quantum key
distribution (QKD). Standard QKD networks depend on trusted nodes to relay keys
across long distances, however, reliance on trusted nodes in the quantum
network does not meet the criteria necessary for establishing a Tor circuit in
the ACN. We address this issue by developing a protocol and network
architecture that integrates QKD without the need for trusted nodes, thus
meeting the requirements of the Tor network and creating a quantum-secure
anonymous communication network.
