Patent ID: 7376835

Claim:
A method for a transaction source and a transaction target to exchange a transaction that cannot be repudiated, the method comprising: (a) receiving a first request for a transaction identifier to identify the transaction, wherein said request includes a source authentication assertion; (b) verifying said source authentication assertion; (c) storing said transaction identifier and information from said source authentication assertion, thereby establishing information making the transaction source unable to plausibly repudiate once it encrypts and sends the transaction; (d) providing said transaction identifier in reply to said first request so that the transaction and said transaction identifier can be sent to the transaction target; (e) receiving a second request for a decryption key to decrypt the transaction once it has been received by the transaction target, wherein said second request includes said transaction identifier and a target authentication assertion; (f) verifying said target authentication assertion; (g) storing information from said target authentication assertion with the transaction identifier; and (h) providing said decryption key in reply to said second request so that the transaction can be decrypted, thereby establishing information making the transaction target unable to plausibly repudiate being a recipient of the transaction.