Some Remarks on Universal Re-encryption and A Novel Practical Anonymous Tunnel

In 2004 Golle, Jakobsson, Juels and Syverson presented a new encryption scheme called the universal re-encryption [GJJS04] for mixnets [Cha81] which was extended by Gomulkiewicz et al. [GKK04]. We discover that this scheme and its extension both are insecure against a chosen ciphertext attack proposed by Pfitzmann in 1994 [Pfi94]. Another drawback of them is low efficiency for anonymous communications due to their long ciphertexts, i.e., four times the size of plaintext. Accordingly, we devise a novel universal and efficient anonymous tunnel, rWonGoo, for circuit-based low-latency communications in large scale peer-to-peer environments to dramatically decrease possibility to suffer from the attack [Pfi94]. The basic idea behind rWonGoo is to provide anonymity with re-encryption and random forwarding, obtaining practicality, correctness and efficiency in encryption in the way differing from the layered encryption systems [Cha81] that can be difficult to achieve correctness of tunnels.