Commercial transactions, time-stamping and trusted entities

The inherent limitation of the use of digital signatures is their inability to provide time-related non-repudiation. While a digital signature attached to a message will have a time-stamped audit trail through the network, digital signatures cannot, in the absence of a trusted entity, provide an non-forgeable, trusted time stamp [OTA94].

The key attributes of a trusted entity are that it is a disinterested third party trusted by the parties to the transaction and subject to the dispute resolution mechanisms relevant to a transaction or record. A trusted entity can perform a variety of functions to facilitate electronic contracts [OTA94]:

• producing a document audit
• storing a record copy of electronic documents
• providing time stamps
• generating authentication certificates to ensure the identity of communicating parties.