A method for prohibiting transacting parties from subsequently repudiating an executed transaction without trusted third party

摘要

A protocol for prohibiting subsequent denial by one of the transacting parties of an already executed electronic transaction. This protocol enables secure Internet electronic commerce without the necessity of using a trusted third party. In this protocol, a sending party transmits to a receiving party, an encrypted first message that includes a desired product encrypted with a required key, but that does not include the required key. The receiving party uses the encrypted first message as evidence of non-repudiation of origin, i.e., evidence of non-repudiation that the sending party sent the transaction. The receiving party transmits to the sending party a second message requesting for the required key. The sending party may use the second message as evidence of non-repudiation of receipt, i.e., evidence of non-repudiation that the receiving party received the transaction. Thereafter, the sending party publishes a third message with the encrypted required key on the sending party's web site, and the receiving party is required to go to the web site to fetch the third message. This protocol therefore ensures non-repudiation of origin and non-repudiation of receipt without a trusted third party involved in the electronic transaction.