Signtiming Scheme based on Aggregate Signatures

The aim of timestamping systems is to provide a proof-of-existence of a digital document at a given time. By timestamping a digital document after it has been signed by concerned parties, we know when the document was signed. Timestamping services also provide the non-repudiation and long term properties for digital signatures. Combining both digital signature and provable timestamping guarantees authentication, integrity and non-repudiation of digital documents. In this paper, we introduce such a service, so called signtiming, that signs and timestamps in a single step. Our scheme is based on an ID-based aggregate signature and is secure in the random oracle model.