SCHENECTADY, N. Y.

December 11, 2002

Authentidate Holding Corporation (Nasdaq: ADAT), today announced that its wholly-owned subsidiary, Authentidate International AG, will provide its electronic time stamps to T-Systems, a leading global service provider and division of Deutsche Telekom. The time stamps will be marketed by T-Systems to its customers via the Internet and will be used internally by T-systems as well. These time stamps meet the requirements of the German Digital Signature Act and remain valid for up to thirty years. Time stamps are affixed via the Internet and do not require users to invest in special hardware or software.

Once the time stamp is obtained from T-Systems and Authentidate International AG it is deemed to be proof of an electronic document having existed in that form, containing that particular content at the time of stamping and, therefore, will have the full benefits of the German Digital Signature Act in a European court of law. From a legal point of view, this procedure places electronic data on a par with paper documents. Storage in paper form, an expensive and labor-intensive step, is no longer necessary as proof for potential subsequent disputes.

Electronic time stamp users in companies or public institutions can order time stamps simply and quickly via the Internet. Which documents are affixed with a time stamp and at what point is left entirely to the discretion of the users themselves and it is irrelevant whether only a few files or several thousand a day are stamped.

A document with a qualified time stamp issued by T-Systems and Authentidate International AG permanently establishes it as legally binding irrespective of whether the file is a text document, a spreadsheet, a graphic, or any other format. The time stamp is created by a certified authority. T-Systems and Authentidate International AG are both operating such legally certified trust centers.

"By consolidating the competences of T-Systems and Authentidate International AG, time stamps can now give every company in Germany an economic advantage -- without additional investments in hardware or software," emphasizes Dr Franz-Peter Heider of T-Systems. "This means a great cost-savings potential without investment risk especially in a tight economic situation."

Jan C. Wendenburg, Chairman of the Executive Board of Authentidate International AG, adds, "We are delighted that e have been able to convince T-Systems of the efficiency of our service. We are sure that this cooperation will considerably simplify the application and use of time stamps for our customers."

About Authentidate International AG
Authentidate International AG (www.authentidate.de), Düsseldorf Germany is the first Accredited Certification Provider, certified by the German Regulatory Authority for Telecommunications and Posts (RegTP), focusing legal binding timestamps compliant to the strong German electronic signature laws and European signature directives. Thus, the time signatures supplied by Authentidate International AG for any electronic data provide the highest level of protection recognized by law in the form of qualified digital signatures.

Authentidate is also the first accredited vendor focusing business process solutions, based on electronic signatures and time stamping technology. Authentidate's Business Solutions feature short ROI (return of invest) cycles, simple integration, low operating expense and ease of use. The unique design enables most customers for the first time receiving substantial profit contributions from signature and time stamping technologies.

The Authentidate Group is worldwide present in Europe, USA and through partners also in Asia. Authentidate Holding Corp, Inc. located in USA (New York) is listed on the NASDAQ stock exchange (ADAT) and in Germany (WKN 893715).

About Authentidate Holding Corp.
Authentidate Holding Corp. (AHC) is the holding company of five business units: DocStar, Authentidate International AG, Authentidate, Inc., DJS Marketing Group/Computer Professionals International and Trac Medical Solutions, Inc. Authentidate and Authentidate AG provide the authentication of digital data through its proprietary and patent pending technology. Authentidate is establishing itself as the authority on "content security," a growing sector of the electronic network security infrastructure market Trac Medical uses the Authentidate service to improve speed, accuracy and security in processing medical forms. These three business units comprise the Authentidate Segment for financial reporting purposes. DocStar sells a complete line of document imaging products and DJS delivers professional services centered on systems integration projects, staff augmentation, out-tasking and outsourcing services, and resells computer related products.

About T-Systems
With restated revenue of 11.9 billion euros in 2001, T-Systems -- a division of the Deutsche Telekom Group -- is a leading global service provider. By combining expertise in both information technology and telecommunications, it possesses the resources necessary to create true e-business and convergent solutions in the areas of application service providing (ASP), customer relationship management (CRM) and electronic marketplaces. T-Systems currently has approximately 43,500 employees in over 20 countries. The company is based in Frankfurt, Germany.

Further information on the company and its service offering is available online at www.t-systems.com.

This press release contains foiward-Iooking statements within the meaning of section 27A of the Securities Act of 1933 and section 21E of the Securities Act of 1934. When used in this release, the words "believe," "anticipate," "think," "intend," "plan," "will be," "expect," and similar expressions identify such forward-looking statements. Such statements regarding future events and/or the future financial performance of The Company are subject to certain risks and uncertainties, which could cause actual events or the actual future results of the Company to differ materially from any forward-looking statement. Such risks and uncertainties include, among other things, the availability of any needed financing, the Company's ability to implement its business plan for various applications of its technologies, the impact of competition, the management of growth, and the other risks and uncertainties that may be detailed from time to time in the Company's reports filed with the Securities and Exchange Commission. In light of the significant risks and uncertainties inherent in the forward-looking statements included herein, the inclusion of such statements should not be regarded as a representation by the Company or any other person that the objectives and plans of the Company will be achieved.