In that case you should refer to "SNC" (Secure Network Communications) which is based on GSS API v2 (Generic Security Services).
In general you require an external security product (see SAP note 66687); for sole Windows environments (where server and client are Windows machines and reside in the same Windows domain resp. mutually trusted domains) you can use of the Microsoft SSP (Security Service Provider), namely for NTLM and Kerberos (as of Windows 2000), using a small GSS API wrapper DLL (GSSNTLM.DLL / GSSKRB5.DLL) provided by SAP (see SAP note 352295).
General information on security topics (including Single Sign-On) can be found at http://service.sap.com/security
Regards,
Wolfgang
