The Adaptive Server ADO.NET Data Provider distribution includes a Microsoft SQL Server Reporting Services (SSRS) Custom Data Extensions component, which allows users to store credentials in the reporting server.
This component, named Sybase.AdoNet2.AseReportingServices, is installed along with the Adaptive Server ADO.NET Data Provider in: %SYBASE%\DataAccess\ADONET\dll on 32-bit systems and %SYBASE%\DataAccess64\ADONET\dll on 64-bit systems.