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SOFSEM 2008: Theory and Practice of Computer Science

Volume 4910 of the series Lecture Notes in Computer Science pp 720-730

Proofs of Communication and Its Application for Fighting Spam

  • Marek KlonowskiAffiliated withInstitute of Mathematics and Computer Science, Wrocław University of Technology
  • , Tomasz StrumińskiAffiliated withInstitute of Mathematics and Computer Science, Wrocław University of Technology

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Abstract

In this paper we present a communicational proof-of-work – a new tool that can be used, among others, for filtering messages and limiting spam. Our idea can be regarded as an analogue of regular proofs-of-work introduced by Dwork and Naor. The idea presented in our paper is as follows: the prover has to provide a convincing evidence that he had communicated with other, randomly chosen entity. This approach is essentially different from previous proofs-of-work, because fulfilling this requirement does not depend on resources owned by the prover (e.g. sender) only. Thanks to this, even if the adversary (e.g. spammer) has an access to much more efficient computers, he does not have any important advantage over regular, honest users of the system. We also demonstrate some other applications of the presented idea as well as some extensions based on its combination with regular proofs-of-work. Together with algorithms we also briefly describe a proof of our concept i.e. working implementation. We present some experimental data and statistics obtained during tests of our application.