Optimistic fair exchange in a multi-user setting

Yeveniy Dodis, Pil Joong Lee, Dae Hyun Yum

Research output: Contribution to journalArticle

Abstract

This paper addresses the security of optimistic fair exchange in a multi-user setting. While the security of public key encryption and public key signature schemes in a single-user setting guarantees the security in a multi-user setting, we show that the situation is different in the optimistic fair exchange. First, we show how to break, in the multi-user setting, an optimistic fair exchange scheme provably secure in the single-user setting. This example separates the security of optimistic fair exchange between the single-user setting and the multi-user setting. We then define the formal security model of optimistic fair exchange in the multi-user setting, which is the first complete security model of optimistic fair exchange in the multi-user setting. We prove the existence of a generic construction meeting our multi-user security based on oneway functions in the random oracle model and trapdoor one-way permutations in the standard model. Finally, we revisit two well-known methodologies of optimistic fair exchange, which are based on the verifiably encrypted signature and the sequential two-party multisignature, respectively. Our result shows that these paradigms remain valid in the multi-user setting.

Original languageEnglish (US)
Pages (from-to)318-346
Number of pages29
JournalJournal of Universal Computer Science
Volume14
Issue number3
StatePublished - 2008

Keywords

  • Fair exchange
  • Public key cryptography
  • Security protocol

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)

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