Achieving fair non-repudiation for web services transaction

For safeguarding the interests of web services transaction parties, non-repudiation mechanism need assure fairness and timeliness. The non-repudiation service implemented currently mostly does not consider the requirement of fairness and the fair non-repudiation protocols to date can not be suitably applied in real environment due to its complexity of interaction. This paper discusses the transaction-oriented non-repudiation requirement for web services transaction, analyzes the constraints of the traditional model for the available fair non-repudiation protocols and designs a new Online-TTP fair non-repudiation protocol which provides a fair non-repudiation solution to secure web services transactions and can be embedded into single web service call. Evidence chaining is exploited to decrease the overhead of evidence verification and management and alleviates the overhead of certificate revocation checking and time-stamp generation for signatures. The protocol owns properties of strong fairness, timeliness, efficiency and practicability.