SSF configuration and Single Sign On

Hello,

We are utilizing the portal UME to authenticate via Active Directory LDAP. We are using Portal single sign on tickets to then authenticate into SAP R/3.

The problem we are having concerns how electronic signatures authenticate. It seems that SSF points to the local SAP R/3 authentication mechanism for electronic signatures, for example, tcodes CO60, QA11, etc. We were not planning on needing an active "internal" R/3 password, but due to the e-sig using the internal authentication mechanism, we have to set a local SAP password in R/3. Is there a way to configure SSF to use an external authentication source, for example, like a connection back to the portal UME?

Thanks in advance,

Ryan