Flexible-Routing Anonymous Networks Using Optimal Length of Ciphertext

Koji CHIDA  Masayuki ABE  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E88-A   No.1   pp.211-221
Publication Date: 2005/01/01
Online ISSN: 
DOI: 10.1093/ietfec/e88-a.1.211
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Application
Mix-net,  Hybrid Mix,  Onion Routing,  anonymity,  

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We present an efficient Hybrid Mix scheme that provides both routing flexibility and the optimal length of ciphertext. Although it is rather easy to embed routing information in the ciphertext, and a scheme that provides the optimal length of ciphertext is already known, it is not a trivial task to achieve both properties all at the same time. A critical obstacle for providing the optimal length of ciphertext is the session-key encapsulation header in a ciphertext that carries the encrypted session-key to each router, which linearly increases according to the number of intermediate routers. We solve this problem by improving the previously reported Hybrid Mix scheme such that the resulting scheme benefits from routing flexibility with a constant length of such headers. Our basic scheme is only secure against honest, but curious intermediate routers. Therefore, we further address the robustness issue to prevent malicious behavior by incorporating and improving an existing efficient approach based on the Message Authentication Code.