Analysis for Excel: SSO allowUnsecured

Hello,

I configured SSO for Analysis for Excel according to "1785270  - How to configure AD SSO for Advance Analysis for MS Office with Business Objects BI 4.0".

For me it only works when i allow unsecured connections in my web.xml

            <param-name>idm.allowUnsecured</param-name>

            <param-value>true</param-value>

There is a strong warning about it. What can I do that SSO also works with this parameter set to false?