how to fix the problem "Message: AADSTS500132: Assertion is malformed and cannot be read.

Question

Hi there,

We implemented SSO solution for our Office 365 tenant to RSA-Security by SAM2.0 protocol . We developed SAML provider by ourself.

Here is our flow:

• Federating our domain to our own login-page which can received SAML request from O365
• Users browses to login O365 page of Microsoft.
• O365 will redirect users to our login page on RSA-Security
• Our own login page will authenticate and response to O365 by sent back SAML Responds assertion to O365
• We cannot login to our O365 tenants, with the error:"Message: AADSTS500132: Assertion is malformed and cannot be read".

We have checked the SAML tracer files we collected: The SAML request and response look normal to us and in the SAML response RSA is sending “success” which means the authentication was successful from RSA-Security side.

Also from the user event monitor on RSA-Security Cloud we could observe that authentication was performed successfully and the assertion was sent successfully for the user.

We researched but can't find out the reason for this phenomenon.

Could anyone check and give us any explanation

Thanks so much

Regards,

Roberto