I am trying to setup a OneLogin SAML authentication with an IDP on Azure AD in PHP and I have got the XML with all the credentials. I have little experience with these so I cannot seem to choose the right x509 cert in the XML file 😅. When I perform the request I get this:
Signature validation failed. SAML Response rejected
invalid_response
I also have .cer files but I am not really sure how to use them...
Can you give me a hand or point me in the right direction to helpful documentation?
"Signature validation failed. SAML Response rejected" means that the signature validation process failed.
In this case, the x509 cert of the IdP registered config file is wrong and differ than the one used by the IdP.
The certificates should not be different than the one you registered at php-saml to validate the signature, that the reason for the invalidation. For example, your php saml certificate should be in your SAMLResponse like:
<ds:X509Certificate>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</ds:X509Certificate>
Check out issue #216 and #434 around the similar explanation.
Further, you can refer to Use a SAML 2.0 Identity Provider (IdP) for Single Sign On article for some more pointers for SAML setup.