A Web Services Based Architecture for Digital Time Stamping

This paper describes the results of a research activity conducted cooperatively by an academic and an industrial party. It presents a practical solution for and an experience in the implementation of time stamping services and their exposition to the Internet. We present the main state-of-the-art algorithms for time stamping applications, thoroughly discuss pros and cons of each technique, and highlight the crucial issues raised by their practical implementation. Then we present an architecture which provides both relative temporal authentication, based on a linear linking scheme, and absolute temporal authentication, based on publishing mechanisms as well as on a trusted time source. In order to guarantee ubiquity and interoperability, the actual implementation of the proposed architecture relies on the emerging Web services technology for exposing time stamping functionalities to the Internet. Experimental tests have demonstrated the effectiveness of the proposed solution.