EXHIBIT 99.1

                     CERTIFICATE OF CHIEF EXECUTIVE OFFICER
                           AND CHIEF FINANCIAL OFFICER

         This Certificate is being delivered pursuant to the requirements of
Section 1350 of Chapter 63 (Mail Fraud) of Title 18 (Crimes and Criminal
Procedures) of the United States Code and shall not be relied on by any person
for any other purpose.

         The undersigned, who are the Chief Executive Officer and Chief
Financial Officer, respectively, of S1 Corporation (the "Company"), hereby each
certify as follows:

         To the knowledge of the undersigned, the Quarterly Report on Form 10-Q
of the Company (the "Report"), which accompanies this Certificate, fully
complies with the requirements of Section 13(a) or 15(d) of the Securities
Exchange Act of 1934, and all information contained in the Report fairly
presents, in all material respects, the financial condition and results of
operations of the Company.


         Dated this 14th day of November 2002.

                                   /S/ JAIME W. ELLERTSON
                                   --------------------------------------------
                                   Jaime W. Ellertson, Chief Executive Officer

                                   /S/ MATTHEW HALE
                                   --------------------------------------------
                                   Matthew Hale, Chief Financial Officer